MotorAge - February 2025

HYBRID MOTOR GENERATORS

Depending on whom you listen to, you might think effective filtration is all about maximum filter efficiency. That just isn’t the case. With 85 years of experience, WIX® understands the best filters optimize engine protection and performance.

To strike the right balance, WIX considers all key performance benchmarks—not only contaminant removal. When you choose WIX filters, you’re choosing the optimal levels of efficiency, capacity and pressure drop for long-term, reliable filtration and maximum engine protection.

ENGINEERED FOR EXPERTS

12 The Basics of Driveline Noise Diagnostics

Listening and learning to understand what you hear will speed up your diagnostic process, and improve your efficiency and accuracy.

Erik Screeden

18 Cylinder Bore Distortion

Understanding the complexities of cylinder bore distortion

Mike Mavrigian

24 Hybrid Motor Generators

The essential guide to the Motor Generator Unit and high voltage systems maintenance

Jeff Taylor

31 The Proof Is in the Pudding

Chasing driveability concerns means pursuing the complaint. But unless you want a ‘comeback,’ you had best find the cause, that’s a given. However, being efficient in this process is a bonus.

Brandon Steckler

36 Hybrid Tutorial

Did you know that internal combustion engines in hybrids were different?

Craig Van Batenburg

50 The Trainer #157

Investing in the Right Tool

Brandon Steckler

ONLINE

Motor Age is adding more videos to its digital warehouse of resources in 2025, including several new series created and hosted by Erik Screeden, our Technical and Multimedia Content Director. Around the Wheel breaks down technical topics ranging from driveability and engine management to steering, suspension, and ride control. Follow Motor Age on YouTube so you never miss a technical lesson from Screeden or his fellow technician, Motor Age Technical Editor Brandon Steckler.

DEMAND FOR TECHNICIANS

The 2024 Transportation Technician Supply & Demand report published by TechForce Foundation provided a boost of encouraging news when it comes to the future technicians needed to staff automotive service bays. For the first time in a decade, there was an increase in the number of post-secondary graduates in not just automotive, but in collision, diesel and aviation, too. The demand still remains greater than the supply of new technicians, but “progress is being made in filling the pipeline.”

EDITORIAL

GROUP EDITORIAL DIRECTOR

Chris Jones / christopherj@endeavorb2b.com

EDITOR

Mike Mavrigian / mmavrigian@endeavorb2b.com

MANAGING EDITOR

Joy Kopcha / jkopcha@endeavorb2b.com

TECHNICAL AND MULTIMEDIA CONTENT DIRECTOR

Erik Screeden / escreeden@endeavorb2b.com

TECHNICAL EDITOR

Brandon Steckler / bsteckler@endeavorb2b.com

ASSOCIATE EDITOR

Madison Gehring / mgehring@endeavorb2b.com

CONTRIBUTING WRITERS

Jeff Taylor, Craig Van Batenburg

ART AND PRODUCTION

ART DIRECTOR

Emme Osmonson

PRODUCTION MANAGER

Mariah Straub

AD SERVICES MANAGER

Karen Runion

SALES

ASSOCIATE SALES DIRECTOR

Mattie Gorman-Greuel / mgorman@endeavorb2b.com

DIRECTOR OF BUSINESS DEVELOPMENT

Cortni Jones / cjones@endeavorb2b.com

ACCOUNT EXECUTIVES

Kyle Shaw / kshaw@endeavorb2b.com

Marianne Dyal / mdyal@endeavorb2b.com

Annette Planey / aplaney@endeavorb2b.com

Darrell Bruggink / dbruggink@endeavorb2b.com

Sean Thornton / sthornton@endeavorb2b.com

Diane Braden / dbraden@endeavorb2b.com

Lisa Mend / lmend@endeavorb2b.com

Chad Hjellming / chjellming@endeavorb2b.com

ENDEAVOR BUSINESS MEDIA, LLC

CEO

Chris Ferrell

COO

Patrick Rains

CRO

Paul Andrews

CDO

Jacquie Niemiec

CALO

Tracy Kane

CMO

Amanda Landsaw

EVP TRANSPORTATION

Kylie Hirko

BUSINESS STAFF

VP/GROUP PUBLISHER

Chris Messer

PUBLISHER

Andrew Johnson

BUSINESS DEVELOPMENT DIRECTOR, MOTOR AGE TRAINING

Michael Willins

CUSTOMER MARKETING MANAGER

Leslie Brown

AUDIENCE DEVELOPMENT MANAGER

Tracy Skallman

SALES COORDINATOR

Jillene Williams

HOW TO REACH US

ENDEAVOR BUSINESS MEDIA LLC.

30 Burton Hills Blvd, Ste. 185, Nashville, TN 37215

Phone: 800-547-7377

CUSTOMER SERVICE

Subscription Customer Service 877-382-9187; 847-559-7598

MotorAge@omeda.com PO Box 3257 Northbrook, IL 60065-3257

REPRINT SERVICES reprints@endeavorb2b.com

MEMBER OF:

Gun Safety

Do you, and your employees, know what to do if a gun is found in a customer’s vehicle during a service appointment?

AS YOU ARE LIKELY AWARE, MANY states allow the concealed carry of firearms (most requiring permits). Unfortunately, some firearm owners tend to “store” a handgun in the vehicle glove box. While this form of transport may be legal in your state (laws vary), this presents a serious concern if the firearm is present when the vehicle is brought in for service. For example, if part of the service involves replacing the cabin air filter, this involves accessing the glovebox. Of course, this concern isn’t limited to a glovebox. This applies to a firearm that is present in any area of the vehicle.

Even though the firearm may be possessed and stored legally, if you encounter a firearm in the vehicle, STOP. Do not touch the gun. One option might be to ask the customer to re-schedule the service visit at such time when the owner can deliver the vehicle with the gun removed.

Never allow a firearm to be handled in your shop by anyone (shop employee

or vehicle owner). While the vehicle owner may not have intended to raise a concern, for future reference, politely inform the owner to be sure that any firearms are removed from the vehicle prior to visiting your shop. You may want to consult with your local police department and/or your attorney to establish a safety protocol that protects your shop from any potential liability.

Consider informing customers to please remove any firearms from the vehicle before any service appointments. The risk of unintended discharge is too great, and is to be avoided at all cost. Inform your technicians to never touch a customer’s firearm, and to alert the shop manager of the presence of a firearm immediately.

This has nothing to do with the right to (legally) bear arms. It’s simply a safety issue. Most responsible gun owners would never leave a firearm unattended, but there are many firsttime gun owners who are oblivious to this basic safety concern.

MIKE MAVRIGIAN MOTOR AGE // EDITOR mmavrigian@endeavorb2b.com

Viper Rear Glass Break

Be aware that 2015-2017 Dodge Viper rear glass is susceptible to cracking/breaking. The liftgate glass may break if the rear defogger (electric backlight/EBL) has been turned on. This is caused from carbon fiber trim contacting the EBL grid. The fix involves installing anti-squeak tape.

Use isopropyl alcohol and a clean rag to clean the two areas of the glass shown in the accompanied photo. Use a plastic trim stick to open the gap between the glass and the carbon fiber trim. The anti-squeak tape must not be placed beyond the defogger grid for appearance purposes. Cut two pieces of Mopar Anti-Squeak Tape (P/N 05019054AA) at 0.75-inches (19mm) and apply to the glass. Use the trim stick to smooth out the tape to ensure good adhesion.

Wheel Studs

Replacing wheel studs is best done by using a manual press tool to remove the old/ damaged stud. Forcing the old stud out by hitting with a hammer can potentially result in hub flange distortion/warpage. In order to install a new stud, you may be tempted to thread-on a nut and draw the stud using an impact wrench. This can over-stress the stud and damage the splines. A superior approach is to insert the stud from the backside of the hub, initially engaging the splines. Then place a thick flat washer (apply a thin coat of lube on the washer’s exposed side). Using a spare open-style wheel nut, place the nut onto the stud threads with the flat side of the nut contacting the washer (or generic nut of the appropriate size) and draw the stud fully into place until the stud head is fully seated flush against the rear of the hub flange.

Crank Flange Bolts

Whenever servicing a flywheel or flexplate, before installing, check to see if the threaded bolt holes in the crankshaft flange are blind or open to oil. If in doubt, check the service manual. If the holes are open to crankcase oil, a thread sealer will be required on all bolts. If this is overlooked, an oil leak will result, which can easily be mis-diagnosed as a rear main leak.

Extended Drainback

Ford now recommends a 15-minute oil drain for the 5.0L engine. After the engine is operated at temp, shut off, remove the oil fill cap, dipstick and filter, and allow 15 minutes for full drain. After installing the drain plug and new filter, add the specific amount of oil (per the service manual). Allow 15 minutes for the oil to fully settle into the sump. Start the engine, operate for a few minutes, shut the engine off, and wait another 15 minutes before checking level. Due to a relatively slower drainback, if you rush the job you can easily end up over-filling the sump.

Mazda PCM Re-Flash

If you encounter a 2018-2019 Mazda6 vehicle with the MIL on and DTC P2096:00 (air fuel too lean), the issue might be the PCM. Due to improper control logic, a false error may be detected. The PCM has since been modified. This concern applies to vehicles equipped with a Mitsubishi PCM (some vehicles may feature a Denso PCM). If the vehicle has a Mitsubishi PCM, reboot the IDS to clear memory, then reprogram using the latest IDS software available.

Reprogram using the latest calibration. Verify that the file name matches with the following calibrations:

Trans. File Name Note

2018-2019 Mexico

M/T PYH1-188K2-H

A/T PYH2-188K2-H w/o cyl deactivation

A/T PYH3-188K2-J with cyl deactivation

2019 – 2020 Mexico

M/T

PXD6-188K2-B

A/T PXD7-188K2-B w/o cyl deactivation

A/T

PXD8-188K2-B with cyl deactivation

Clear all DTCs. Start the engine and confirm that no warning lights are illuminated. Record the customer’s radio presets.

Disconnect the negative battery cable and wait at least 30 seconds to reset the fuel control learning data.

Re-connect the negative battery cable and re-enter any presets.

Super Duty Reprogram

You may encounter a 2020 Ford F-Super Duty truck equipped with a 6.7L diesel engine that exhibits a forced idle condition and/or DTCs P0300, P0308, P0603, P203B, P208B, P208C, P2201, P24C2, P27B4, P07F6 and/or P27B5 stored in the PCM. This may be due to various strategies in the PCM software.

• Reprogram the PCM using the latest available software.

• Allow the vehicle to sit indoors to increase DEF tank temperature above 32 °F.

• Start the engine and allow it to idle for 10-15 minutes.

• Drive the truck forward at wide-open throttle for up to two minutes. It’s important to not back off the accelerator pedal when trying to get it out of forced idle. If it does not come off of forced idle mode after two minutes, stop the truck and idle for a few minutes before trying again. Full power will be restored once the forced idle condition is resolved.

8th Gear Takeoff

If a customer’s 2021-2022 Ford F-150 (equipped with a 10R80 MHT transmission) exhibits a start in 8th gear after coming to a stop and/or has no reverse, this may be due to the driver applying the accelerator and brake pedals at the same time during regenerative braking. This primarily applies to vehicles built on or before Nov. 15, 2022. The fix: reprogram the PCM with the latest software version, and inform the driver not to apply the throttle pedal and brake pedal at the same time.

Professional Diagnostics

The next generation of scan tools with the most advanced OE level vehicle coverage supporting scanning, live data access and complete bi-directional functions.

ADAS Recalibration

Heavy Duty Diagnostics

Heavy duty solutions to help you get the repair done right and the vehicle back in operation.

Test, Tune and Analyze

Test, analyze and diagnose your vehicle electrical and mechanical systems. A seamless, full-system solution that guides you from setup through calibration in half the time.

The Basics of Driveline Noise Diagnostics

Listening and learning to understand what you hear will speed up your diagnostic process, and improve your efficiency and accuracy.

BY ERIK SCREEDEN

ASK ANY TECHNICIAN, and they will tell you that the bane of their existence is the elusive noise, vibration, harshness (NVH) complaint. Those nuisance concerns that all too often turn into a nightmare game on the telephone where the customer tries to articulate their concern to a service writer, who in turn tries to explain those same concerns to the technician. Driveline noise falls squarely into this category. Perhaps not as intermittent as that under-dash squeak that seems to only happen on a Tuesday morning between 7:00 a.m. and 7:03 a.m. during a waxing crescent moon, but driveline noises can drive technicians bonkers if they don’t understand what they are hearing.

When one stops and thinks about all the

rotating mass in the driveline of any given vehicle, it’s no wonder that driveline noise complaints are one of the more common noise-type jobs a technician sees. Within the driveline of a vehicle, you have a few main categories: transmission, transfer case/PTU, driveshaft, differentials, axles, and wheel end. Now every ICE vehicle on the road has these components to some varying degree, and they all present their own challenges when diagnosing noise complaints. But for this article I want to concentrate and dive into the differential, axle, and wheel end side of the equation.

Understanding the Basics

The differential’s key role is to allow the drive wheels to rotate at different speeds while transmitting power from the engine. This function is essential for smooth and stable vehicle operation, especially during cornering. As a vehicle turns a corner, the wheels on the outside of the turn need to spin faster than those on the inside of that turn. Because of this, the drive wheels of the vehicle need to be able to spin independently of one another while still providing power to maintain traction

and reduce tire wear. This is where the differential steps in.

If you think about a traditional axle assembly found in the rear of a pickup truck, contained within you will find, among other things, the differential carrier. Let’s say this is an open differential. So, no clutches, governor-operated lockers, torsions, etc. Contained within the carrier you will find side gears that spline directly with the axle shafts, and spider gears (also known as satellite gears) that ride on a pin that meshes with the side gears. These gears take the rotational energy from the driveshaft and redirect it to the axles. These gear sets allow the rear tires of this truck to rotate at different speeds while going around corners.

Many of you have probably operated a vehicle that has a locked differential, and I don’t mean a mechanical locker that can ratchet and unlock in turns, but a solid unit, meaning both drive tires will spin at the same rate. It’s very common in performance and off-road applications. People will install a full spool in place of the carrier, or a mini spool that replaces the side and pinion gears on an open carrier.

Or, if they are on a real bare bones budget, they may even break out the MIG welder and build what’s commonly referred to as a “Lincoln locker” where one simply welds the spider gears and side gears in place. Any of the afore-mentioned options prevent any differential action, and they apply power to both tires equally. The tradeoff in this situation is turning radius, tire wear, and extreme stress on other components of the driveline, like the axles. Differentials, regardless of design, are an important part of the equation when it comes to vehicle driveability and overall longevity of the driveline, but with all that componentry comes the added opportunity for items to wear, become damaged, and in turn make noise.

A differential consists of a network of components that work together to perform power transfer and differential action. This network of intricate componentry is susceptible to wear due to its heavy usage, which often makes itself known by noise and vibration heard and felt by the driver. Again, as we did earlier let’s start by talking about the basic open carrier. The rear axle assembly in our imaginary pickup truck will be connected to the driveshaft via a flange. That flange will be splined to a pinion gear. The pinion gear will mesh with and drive a ring gear that is bolted to a differential carrier housing. That differential carrier housing will contain spider gears that ride on a pin that is incorporated into the housing assembly and that mesh with side gears that are splined to both axle shafts. The pinion gear, the carrier assembly, and axle shafts are all supported by bearings. So, as you can see there is a lot of opportunity for wear and noise to develop. The challenge is to be able to identify some of these noises and start to develop a preliminary diagnosis while test driving the vehicle — before you need to start tearing anything apart.

It’s

All About Having a Plan

When it comes to noise diagnostics, and what the root cause is, there is never a sil-

ver bullet, especially when dealing with the vehicle’s driveline. But, with experience, a technician can develop a mental diagnostic flow chart to follow depending on when or how the noise presents itself. Start with the most basic of noises, a growling or whirring from the wheel end. Most technicians are familiar with the telltale sound of a failing wheel bearing or axle bearing. While serviceable tapered roller bearings are found in some older applications, modern sealed unit bearings are found front and rear of many applications, as well as modern full and semi-floating truck axle bearings make wheel bearing noise diagnostics fairly straightforward. Pitch changes as vehicle weight is shifted and the suspension is loaded and unloaded make finding the problem a straight-forward affair. The pitch change that gets louder as you load the bearing, and quieter as you unload is not only a clear indication of a problem, but also where the problem is located. Galling, pitting, or wear located on the bearing rollers, the bearing race, or as you can see in Figure 1, the axle shaft itself, will generally present noise that will change with loading.

Where things start to get a little trickier is when we move farther into the axle or transaxle assembly. Remember the differential carrier? That carrier assembly is going to ride in the housing on two carrier bearings. These carrier bearings will typically present themselves as noise that starts above about 20 mph and generally will continue to increase in intensity as vehicle speed increases. As torque is applied to the ring gear via the pinion, it loads those carrier bearings. Just like a loaded wheel bearing, these will present themselves as grinding or growling noises typically on acceleration above that 20-30 mph mark. Like the wheel bearing, galled or otherwise failing carrier bearings and damaged races (Figure 2) are easily identified when the technician learns what to listen for.

Moving forward from the carrier

you will find the pinion gear. Just like the carrier, the pinion is supported by two bearings, an inner and outer. And just like a carrier bearing, these generally are a tapered roller. But how these bearings react under load when worn when compared to the carrier bearings, at least in my experience, is a little different. When the initial setup of a ring and pinion gear set is performed, the pinion bearing preload is set. Often, pinion preload is set

and maintained by a collapsable sleeve known as a “crush sleeve.” While a solid spacer and shims are used in some larger or performance applications, the crush sleeve is the most often used component to set and maintain this extremely important specification. The reasoning behind it is simple. It is less expensive and faster to set up. The downside is, over time, pinion bearing preload can be lost due to wear or abuse. Just like in a wheel bearing that uses a tapered roller cone and cup, proper bearing preload is everything. Too little preload is just as detrimental to a tapered roller bearing as too much, and when damage to either pinion bearing’s cup or cone occurs, noise is often the result.

Pinion bearing noise is the leading misdiagnosed noise within the rear differential. Typically, when the pinion bearings lose their preload or become damaged, the result is a whirring or whine most often heard on deceleration. This is often incorrectly attributed to a worn ring and pinion gearset. When load is applied to the pinion through the driveline from the engine/transmission under acceleration and cruise, the bearings — even when preload is incorrect or there is wear present in the cone or cup — often will operate quietly. The load on the pinion and its bearings will often mask any minor noise because it shifts where the pressure is placed on

the pinion bearings themselves. Under coast and deceleration, when the pinion is driven by the wheels and both contact and load on the pinion bearings changes, often that is when the noise will present itself. Again, it’s been my experience that this noise is incorrectly attributed to a worn or incorrectly set up ring and pinion. Keep in mind, while technicians should be making preliminary deductions while test driving the vehicle, it’s then incredibly important to follow up those hypotheses with further inspection once back in the bay.

Rhythmic clunking, grinding, whirring, and what is often described as a “zing,” are often attributed to the gearset itself. Wear, abuse, incorrect setup/break in, and material failure can all lead to noise complaints that stem from ring and pinion gears. Insufficient lubrication can prematurely wear a gearset, greatly changing the way the pinion and ring gear contact one another, leading to harmonics. Customers who put off that leaking pinion or axle seal replacement and don’t consistently check their gear oil level will eventually find themselves with a much more expensive repair.

Fluid contamination due to water intrusion is another common cause of gearset (and bearing) failure. Anytime the driveline is submerged, especially above the vent, all those components should be serviced. Another common driveline noise complaint is “clunking.” A clunking sound that is consistent when moving forward and in reverse in a turn or a straight line is a tell-tale sign of chipped (Figure 3) or sheered teeth on the ring or pinion gears (Figure 4). Overstressing the gearset, from things like oversized tires, is the root cause of failures like this. This is compounded by the ability to make significant power increases relatively inexpensively on many of the modern engine platforms like LS/LT, Hemi, and Coyote. Enthusiasts quickly find that proverbial “fusible link” in their drivetrain as soon as they start making power and finding traction, and often a failure with the differential and/or axles shafts themselves occurs.

Getting Even Deeper

Within the differential carrier case and internals, you also have ample opportunity for noise. Regardless if you have a standard open differential, a limited slip like an Eaton Posi, an Auburn Grip-N-Loc, or a locker like the Gov-Loc, mechanical failures due to material failure, abuse, and lack of or improper maintenance are common. Remember, the main purpose of the differential is not only the transfer of power, but to allow the wheels to spin independently when navigating turns. Unusual noise or vibration in a turn while there is a difference in wheel speed between the inner and outer wheels most likely can be attributed to an issue within the differential carrier itself.

As we have stated, most carriers contain spider and side gears that allow this differential action to take place. Clunks and gear noise are not unlike a broken ring and pinion, but when they can only be heard while turning, that’s a clear indication of damage to those spider or side gearsets. Broken teeth due to abuse or material failure (Figure 5) and worn or pitted gears due to high mileage and/or lack of maintenance are the top causes of these noises. In instances of complete internal failure, the vehicle will be unable to transfer power to the drive wheels at all. Many high school-aged drivers thrill themselves while discovering the joy of converting rubber into smoke, only to quickly have that joy dashed by the unscheduled rapid disassembly of the internal components of their rear differential due to the extreme heat that is produced, especially with an open carrier (Figure 6).

Chatter is also a common complaint with customers who own vehicles that use clutch or cone style limited slip differentials. Improper differential service procedures are often at the root of these complaints. Often OE and aftermarket carriers require specific fluids and friction modifiers to ensure that the clutch disks or cones found within these differentials can function correctly and smoothly. While

most technicians know that friction modifier is generally required to be added to the differential when a gear oil service is performed on limited slip differentials, many technicians do not realize that the gear oil itself plays an important role in the limited slip differential’s ability to operate correctly.

One of the benefits of a clutch style limited slip differential is that they are rebuildable, but often the aftermarket clutches available require the use of non-synthetic oils in addition to the correct friction modifier for the clutches to perform properly. Use of synthetic gear oil, even if specified from the OE with some aftermarket rebuild kits, will cause an over aggressive limit slip differential. Often the customer will come back within a few hundred miles of service complaining of chatter and binding in turns when this takes place. The good news is, typically replacing the fluid with the correct oil and modifier will rectify the situation.

Acoustics (the way noise travels through materials and across space) can be a very fickle thing. Driveline noise, and the way noise and vibration travel through the different components within the driveline will differ from vehicle to vehicle. Take for instance the example of the third generation or what is commonly referred to as the “Fox Body” Mustang. As most of our readers know, these cars came in both a hatchback and notchback design, with the latter being a coupe utilizing a conventional trunk. Some aftermarket ring and pinion gear brands, even when set up correctly, are known for being loud. These noise complaints will be overwhelming from consumers who are driving the hatchback Mustang, but the same brand of gears rarely have any complaints from drivers of a notchback or convertible. The hatchback design tends to reflect noise via the glass hatch throughout the passenger compartment. Since there is no breakup of the passenger compartment like there is in a coupe, the sound will carry farther in the hatchback design. Putting that same

8.8” gearset in an Explorer will often result in the same complaint. Install it in a F-150 — nothing. Trucks versus vans, SUVs versus sedans — the list goes on and on. It’s something to keep in mind when performing a preliminary test drive.

Bringing It All Into Focus

Once back at the shop, with the vehicle up in the air, you need to prove any hypothesis you made during your test drive by safely running the vehicle on the hoist in gear while listening and performing visual inspections. A set of electronic “chassis ears,” a stethoscope, or even a long extension or prybar, will allow you to listen to locations on the axle housing or transaxle closest to places like the axle bearings, carrier bearings, and pinion bearings to determine the root cause.

Shut the vehicle back off and look for leaks. Check fluid levels. Carefully spin driveshafts and axle shafts and feel for rough bearings or unusual play. Having an assistant hold firm one of the drive wheels while spinning the other, especially on an open differential, is an easy way to see if the noise you hear is rooted in the side or spider gears.

We have spent much of this article talking about conventional rear- or fourwheel-drive vehicles, but these same principles hold true when talking about front

differentials, and even transaxles. Keep in mind that many front axle assemblies on traditional four-wheel-drive vehicles will utilize a front axle disconnect, or more rare today, locking front hubs. Hopefully the workorder states the configuration the vehicle is in when the noise occurs, but make sure you are testing with the vehicle in both two- and four-wheel-drive to make sure nothing gets overlooked. And with transaxles, while some of the components in a transaxle are a little different (often the pinion gear is driven off the main shaft for instance, carrier bearings utilizing ball bearings, etc.) these principles for noise diagnostics are the same. When in doubt, lean on service information to familiarize yourself with how power flow takes place.

The Setup Is Important

When it comes to noises that are believed to be associated directly with the ring and pinion gearset, there are a few important factors to keep in mind. Most gear sets are made of high-quality alloys like SAE-ASI 4320 or 8620 Ni-Cr-Mo steel. While thermal expansion of these alloys is minimal, it still exists. The air gap between the ring gear and pinion, otherwise known as backlash, is an extremely important specification.

The backlash is simply the amount of rotation the ring gear can make while the pinion gear remains stationary. This

measurement is taken with a dial indicator and is important because a gearset that is set up too tight — meaning it has too little backlash — will bind when the ring and pinion heat up and expand. A gearset that is too loose — meaning too much backlash — will be louder and can lead to accelerated wear. It is best to follow guidelines from the manufacturer to determine specifications, as it will vary depending on factors such as gear cut (2 cut versus 5 cut), size, and even brand. Backlash specifications for new gears typically fall into the range of 0.006” to 0.012”. While backlash will open up as the gearset wears, too much backlash will eventually present itself as noise heard by the driver.

Fluid deterioration due to contamination or lack of service will accelerate the process of wear on the gearset. Water intrusion, lack of service, and even improper break-in of a new gearset can all lead to premature failure. Evidence of this can be found when visually inspecting the gears. If they have worn past the induction hardening that took place in the manufacturing process, the drive and coast side of the ring gear can appear shinney and pitted, and the gear face on both the ring and pinion can wear down towards a sharp point rather than the plateau of a normal gear face.

Contact patch or pattern is also an important piece of the puzzle in having a quiet and long-lasting gearset. Pinion depth plays just as important of a role as backlash when it comes to the setup of a differential. Using a gear marking compound to pattern a noisy gearset can help you quickly identify problems. When patterning a gearset, you want to load that carrier a bit when doing it. What I typically do is spin the pinion until the teeth with the marking compound are in contact with the pinion gear. I then will place a wrench on one of the ring gear-to-carrier bolts, and use the other hand with a prybar applying pressure on the ring gear itself. I then will just roll that ring gear back and forth half a dozen times until I get a good contact pattern and then inspect. While there are some intricacies involved, for all practical purposes a football shaped contact patch in the middle of the drive and coast side of the ring gear is ideal (Figure 7).

Even if you do not plan to perform services like ratio changes, carrier replacements, or even bearing repair, knowing the fundamentals of how pinion depth, backlash, and contact pattern all come together in a proper setup will aid you in quickly identifying an improper one. Terms like the face of the ring gear (the top), the root (the bottom), drive side (the convex side of the gear), coast (the concave side of the gear), heel (inner end) and toe (outer end) will aid you in being able to effectively communicate and research.

Bringing It Full Circle

Once your findings are confirmed, hopefully it’s time for a repair to take place. While there are many good options like remanufactured units, low mileage take-outs, or components available from numerous drivetrain specialty shops, I encourage you to take on some of these repairs yourself, especially with some of the smaller semi-floating rear axles. Independent front suspension units (IFS) like the AAM 8.25” and 9.25” units found in front of GM trucks starting with the GMT400 body style, or independent rear suspension options like those found in many of the newer crossovers and SUVs offer additional challenges that may be better not tackled by a novice.

A repair like an internal kit on a differential carrier, or even carrier and pinion bearing replacement can be done in most shops with very few specialty tools outside of a press, a dial indicator, and a torque wrench that will read rotational torque. If ring and pinion replacements for repair or ratio changes are something you want to tackle, there are lots of great resources available to allow you to get really in depth in setting you up for success. Many of the gear manufacturers themselves have great online tutorials on how to take measurements like backlash, pattern a gearset, rebuild a carrier, properly shimming the pinion for depth, and setting pinion bearing and carrier bearing preload on a multitude of different styles and brands of axle assemblies.

There are always tips and tricks and specialty tooling to help with the process, so do your research before you start. A Dana/Spicer will differ a bit from an American Axle which will differ a little bit from a GM Saginaw, but there is money to be made by the technician who wants to take on these jobs and do them correctly. I encourage you to do your research, jump in and give it a try. Like always, just make sure you vet your source to ensure you are getting correct information.

Cylinder Bore Distortion

Understanding the complexities of cylinder bore distortion

BY MIKE MAVRIGIAN

WHILE YOUR SHOP likely does not handle intensive engine rebuilds and related machine shop work, here we’ll discuss the topic of cylinder bore distortion and how this occurs. It may come as a surprise to many, but cylinder bores do not remain perfectly cylindrical during engine operation, due to operating heat, cylinder block integrity and the clamping forces that the block experiences when the cylinder head is clamped to the deck.

Is an attempt to optimize cylinder bore geometry vital for the average customer’s engine really necessary? No. Regardless, understanding this subject simply adds to your knowledge base.

Even with the best of intentions and preparation, some degree of cylinder bore distortion is likely to occur under dynamic stress (heat and pressure). The challenge is to understand how these changes take place and to establish procedures that will minimize these changes.

As the block ages and/or is exposed to thermal changes, the casting’s molecular structure will change, however slightly, which will affect bore geometry. In addition, distinct changes in bore shape will take place as the block is assembled. The clamping forces that result from the installation of cylinder heads will, in most cases, cause the bores to slightly distort as the cylinder head bolt clamping forces pull and squeeze metal adjacent to the bores. Sometimes these changes are insignificant, while in other situations, the change can be so dramatic as to cause measurable ring dragging and subsequent loss of power, fuel economy and sealing due to both out-of-roundness and frictional

heat. In other engines, these problems may be compounded if the specific block is severely affected by additional distortion that results from clamping forces caused by bellhousing bolts, water pump bolts, motor mount bolts, etc.

Granted, only the more severe cases will be a cause of concern on a street engine. However, if the goal is to produce an extremely efficient engine, every factor which can affect dynamic ring shape must be considered.

In order to accurately “map” a cylinder bore to obtain a clear dimensional picture of how that bore is shaped from top to bottom, a special “PAT” gauge is used in sophisticated engineering test labs. This is an inclinometer that features a shaft and probe. The shaft is affixed to the deck or torque plate and runs vertically through the bore centerline. The probe runs along the shaft vertically and monitors the bore walls radially. This provides a dimensional perspective view of the entire bore, relative

to the theoretical bore centerline. These testing systems are extremely expensive and are typically used by piston ring and honing equipment manufacturers for analysis applications. This allows plotting the actual shape of the bore in addition to bore diameter. The readings can be displayed radially (viewing the bore from overhead) to show where the bore shifts from the centerline; and in an isometric view (side angle perspective in a variety of view angles) that allows you to see the entire bore in a dimensional manner.

In order to obtain bore diameter readings in a machine shop without the use of this sophisticated equipment, the cylinder walls can be measured with a bore gauge at four different levels at four clock positions (12, 3, 6 and 9 o’clock). Once these numbers have been recorded, place a honing plate (one per deck) on the block, torque the plate(s) to specification, and re-measure the same points to reveal differences that have occurred. However, bear in mind that this will not reveal concentric bore diameter shifts relative to the centerline.

Another variable relating to bore distortion is the cylinder head itself. After measuring the bores (accessing from the bottom of the bores) on a relaxed block (no heads or torque plate), install and torque a cylinder head, and read the bores again from the bottom of the bore to note the changes that have taken place. Next, remove that head and install a different head of the same type and measure the bores once again. If you find a different distortion level/pattern, don’t be surprised. Depending on the makeup of the cylinder head, the clamping forces may reveal a different situation due to the structure of the head, especially on cast heads, due to differences in the hard/soft internal makeup of the casting core. If the head pulls down harder or softer in various areas, this will accordingly affect how the block is stressed, resulting in variations of cylinder bore shape.

As mentioned earlier, when measuring a bore for shape, we need to remember

that, depending on the instrumentation being used, we may or may not obtain a true bore shape. If we use a bore gauge, we are simply measuring bore diameter (and out of round) in specific height levels of the bore, but since we are not referencing from the true bore centerline, we may be overlooking shifts of the centerline at various height locations. If in doubt, or if we know that the radius of the bore has shifted relative to the centerline, we can use a precision bore-truing fixture to correct the problem (such as those offered by BHJ, CWT, etc.), or take advantage of CNC technology in order to establish a “new” bore centerline based on blueprint data from the block manufacturer. The bores can then be “clean-bored” to an oversize, with the cutters referenced from a fixed (and presumably correct) centerline. This will create bore trueness in a static con-

dition, but subsequent changes may still occur when the block is subjected to loads, pressures, and temperature.

The very nature of the block casting process and the material mix can and will create differences from block to block. In other words, if you lined up five blocks with identical casting numbers and identical age, you’ll probably find five different variations of bore distortion. Knowing this, we need to temper our view of block analysis. Just because one small block Chevy of a particular series and casting shows unruly bore distortion in No. 3 bore, this does not mean that this condition will be exactly repeated in every block of that vintage and type. Each block casting is its own animal and needs to be treated as such.

Primary causes of bore distortion in relation to the cylinder head/block joint include clamping load, cylinder head gasket/

combustion seal design, the honing procedure and assembly procedures.

Clamp Load

Cylinder bore distortion is directly related to cylinder head bolt clamp load. The correct clamp load is responsible for preventing the cylinder head from “lifting off,” and to provide adequate compression of the head gasket to retain combustion pressure. If clamp load is insufficient, head gasket failure (combustion and fluid) is sure to result. If clamp load is excessive, the gasket may be compromised via too much crush, and cylinder bore distortion will increase.

The distribution of clamp load also affects bore distortion. If clamping loads are uneven (some bolts under or over spec), the block’s cylinder wall can easily be distorted in a random or unequal manner. It is imperative to use only new cylinder head bolts

and to follow the specific thread treatment and torque (or torque plus angle) specifications recommended by the engine maker.

Cylinder Bore Honing

The use of a deck plate is essential when honing cylinders. A deck plate (also called a torque plate) is a machined unit that is fastened to the block to simulate the installed cylinder head. This allows you to apply the same clamping load that will occur during head installation, which will induce cylinder wall distortion. The plate is installed along with a used (already compressed) head gasket. The honing procedure can then be carried out, aiding in reducing or eliminating bore distortion. If the bores are honed without the use of a deck plate, the bores may measure with a consistent diameter, but when the head is installed, the clamping load stress will influence the bore geometry, resulting in distortion.

THIS GRAPH illustrates how cylinder concentricity can be affected by head clamping, operation with regard to temperature and operation with regard to wall temperature and gas pressure.

PRIOR TO cylinder honing, the deck plate is torqued to specification to simulate the stress placed on the block when cylinder heads are installed.

THREE VIEWS of a “typical” dynamic bore distortion scenario.

As the engine block heat changes during operation (cold to hot and hot to cold), this can and does have an effect on cylinder bore shape. In a perfect world, bore honing would take place with the block maintained at a specific range of temperature, obtained with the use of a specialized “hot honing” system, a temperature management system that most shops do not have. At the very least, simply honing with the use of deck plates will provide an advantage of minimizing bore distortion, providing improved and more consistent piston ring contact.

Head Gasket Considerations

Wire ring-style head gaskets may relax as much as 10–25% after initial assembly. By contrast, MLS gaskets relax less than 10% after initial assembly, thereby providing additional assurance of maintaining proper clamping load and load distribution.

Wire ring-style gaskets require the highest clamp load and can feature high peak loading along the cylinder openings. Again, by contrast, all active (spring function) MLS gaskets have the lowest peak loading along the cylinder openings. MLS gaskets with a built-in “stopper” layer or beaded spacer provide high combustion sealing stress with lower required bolt loading. Active MLS gaskets are designed with formed metal layers featuring contact

and air spaces that work as a spring to provide compressive tension that aids in sealing while requiring lower loading. Active MLS gaskets feature an elastic element which absorbs cylinder head motion. Stopper MLS gaskets also feature a layer of “dead stop” that provides a limit to compression. Stopper-type gaskets feature rigid combustion seals which bend the cylinder head over the seal as a result of clamping loads. Active MLS offers low hardware distortion, since the gasket “gives” to reduce the chance of distorting bores and head decks. This type also provides good recovery for lightweight hardware. However, it may be difficult to generate high combustion sealing stress with an active type MLS. The stopper MLS type of gasket provides high sealing potential, but has the potential to generate high hardware distortion. Determining which type of gasket to use will be based on research data gathered during engine components, engine test assembly and engine operation (on dyno and/or on-track).

Various factors can affect cylinder bore geometry changes.

Factory original cast blocks:

• The density of the material varies

• Core thickness varies throughout

• Machining tolerances are not within acceptable performance guidelines

• Webs or reinforcement of critical areas are not optimal

• Galleys are not sized or routed optimally

• Water jackets and passages do not allow for even heat transfer

• Flow problems in molds create weakened areas

While it should be obvious that addressing cylinder bore distortion is not critical for the average daily driver engine, it’s nonetheless interesting to understand this phenomenon. Addressing this and attempting to correct the condition applies to engine builders who are trying to optimize engine efficiency with the goal of minimizing parasitic drag and to obtain optimal piston ring seal.

Hybrid Motor Generators

The essential guide to the Motor Generator Unit and high voltage systems maintenance

BY JEFF TAYLOR

The hybrid motor generator, also known as the Motor Generator Unit (MGU), is a vital component in modern hybrid vehicles, serving as both an electric motor and a generator. This dual-purpose design allows it to provide additional power to drive the vehicle and capture energy that would otherwise be wasted, such as during braking when it converts kinetic energy into electricity to recharge the high-voltage battery. This continuous switching between motor and generator function enhances fuel efficiency, reduces emissions, and extends battery life. However, over time, the motor generator can experience issues that may reduce its efficiency or, in extreme cases, make the vehicle inoperable. The seamless operation of the MGU, whether capturing free energy while coasting or using electrical power from the battery to drive the wheels, is crucial for maximizing energy use and ensuring optimal performance across varying driving conditions.

Today’s technicians must understand the design of hybrid motor generator systems and be able to identify malfunctions, such as unusual sounds, reduced performance, diagnostic trouble codes, along with warning lights or messages activated by the vehicle’s diagnostic system.

Every hybrid vehicle will still depend on a low-voltage, 12-volt system for all functionality except running the primary electric drive motors. While most technicians will concentrate on the state of the main high-voltage (HV) battery pack, the 12V battery can also fail, and this can easily be overlooked. If the low-voltage system has any issues, the vehicle can basically be disabled: doors might not unlock, onboard computer systems may not function, and — more importantly — the main HV battery won’t charge. Proper inspection of the low-voltage system for proper voltage, current supply and clean tight connections is imperative and cannot be overlooked.

The DC-to-DC converter, or DC power

control module, replaces the traditional alternator in hybrid vehicles. It manages energy transfer between the high- and low-voltage systems, charging the 12-volt battery, powering auxiliary systems, and may provide the 5-volt reference voltage needed by various sensors. The converter typically steps down the high-voltage DC, which ranges from 200-300 volts (with newer plug-in hybrids reaching 400 volts or higher, and high-performance systems exceeding 600 volts), to a steady 14.5 volts for the vehicle’s low-voltage system. These converters can deliver up to 160 amps of 12V DC power.

The DC-to DC converter’s core part is a stepdown transformer. The primary transformer coil typically connects to four PNP transistors on the high-voltage bus, while the secondary coil (low voltage) links to diodes, a serial capacitor and an inductor. The converter’s low voltage output of 12 to 14.5 volts is reached at the junction between the capacitor and

inductor, with the capacitor’s negative side being grounded. The transformer’s high-voltage coil is pulsed by the power transistors, altering the magnetic field and creating a voltage in the transformer’s lower-voltage coil windings. The circuit’s voltage and frequency are controlled and limited in part by the diodes and capacitors under the commands of the DC-to-DC converter module.

Typically, the DC-to-DC module only supplies low voltage output during normal ignition “on” operation or while in driving mode. But on some systems the DC-to-DC converter may be functional when the vehicle is charging or plugged into a wall outlet.

A digital multimeter (DMM) and cables with a CAT III rating are needed to test, diagnose or take voltage readings to diagnose a DC-to-DC converter system.

NOTE: With all high-voltage systems, which are usually identified by orange wiring, it is particularly important to follow the safety instructions provided by the manufacturer.

There are other important items to note while working with DC-to-DC converters. Never splice/tap into or use the DC-to-DC converter power or ground lines for other circuits/devices. Make sure that air can flow over the heat sink, and never use the heat sink as a ground for meters, scopes, or other tools. A scan tool can help you figure out what’s wrong with the DC-to-DC converter by looking at current or saved trouble codes and examining the provided system data. Some manufacturers recommend using a carbon pile tester with an ammeter to test the DC-to-DC converter module output. The carbon pile tester will be attached to the 12-volt battery for this testing. The carbon pile tester will create the load on the system to see if the DC-to-DC converter can supply the needed power. Using the carbon pile tester and a capable scan tool, techs can look at the DC-to-DC converter module voltage and current output data. The ammeter reading on the carbon pile should closely match the DC-to-DC converter module current output reading, and the voltage should

THIS MECHANICAL drawing shows the circuits that are used and required to take the Hybrid High Voltage Battery and reduce the voltage down to the charge and maintain the Low Voltage Battery system, that is still required on today’s hybrid vehicles.

remain between 12.6-15.5 volts. If your shop doesn’t have a carbon pile tester, DC-to-DC converter testing can often be done with bidirectional scan tool testing. The scanner can command the set charging voltage, and the tech can see the changes in voltage as the scanner commands these changes. Be sure to allow a few seconds between voltage setting changes for the battery voltage to stabilize before changing sets points.

There have been two primary types of MGUs used in hybrid vehicles:

• Permanent Magnet Synchronous Motors (PMSMs): PMSMs are widely used in modern hybrids because of their high efficiency, power density, and consistent performance across a range of speeds. They rely on permanent magnets for excitation, allowing for a high-power factor and excellent torque at low speeds, making them ideal for city driving and hybrid efficiency.

• AC Induction Motors (IMs): AC induction motors were used in earlier hybrid models and some high-performance hybrids. Induction motors are robust and can deliver smooth power without requiring magnets. However, they typically operate with a lower power factor and are less efficient than PMSMs. Due to these factors, many manufacturers have shifted to PMSMs for most hybrid applications. PMSMs are known for their high starting torque and are commonly found in hybrids by Toyota, Ford, Kia, Hyundai, Audi, Honda, and other brands. The PMSM MGUs

THIS IS a view of the Megohm meter that is required to perform testing on certain components on the high voltage side of the hybrid electrical system. The tool will apply a specified voltage to the component being tested and will show a reading in MΩ (megohm). 1 MΩ equals 1,000,000 Ω.

use permanent magnets embedded in the rotor, which help produce smooth torque and high-power density. PMSMs operate at a speed precisely aligned with the AC supply frequency. Because the PMSMs use a permanent magnet rotor, these motors synchronize perfectly with the magnetic field in the stator, without slip. PMSMs are highly efficient, particularly at low speeds, making them well-suited for city and urban driving. Their efficiency improves fuel economy and performance, while their ability to fine-tune the power factor through varying excitation enhances their versatility in hybrid vehicle powertrains. The power factor of a hybrid MGU refers to the ratio of real power (useful power) to apparent power (total power) in the system. It is an important measure of how effectively the electrical power is being used, with a power factor closer to 1 indicating more efficient power usage.

THIS SHOWS a specialty tool for diagnosing today’s hybrid vehicles: the milliohm meter. It measures very low resistance, ideal for testing hybrid stator windings, high-voltage battery connections, and inverter circuits. 1 mΩ equals 0.001 Ω.

For hybrid MGUs, the power factor typically ranges from 0.8 to 1, depending on the design and operating conditions. PMSMs often exceed a power factor of 0.9 and that is why they are often favored in both hybrid and electric vehicles.

The first-generation GM Volt hybrid used an AC induction motor. Unlike PMSMs, AC induction motors don’t rely on permanent magnets; instead, they generate a magnetic field in the rotor through induction, like a transformer. In the AC induction motor, the stator serves as the primary side and the rotor as the secondary.

Induction motors are asynchronous motors and run at a speed that does not directly match the frequency of the electrical current running through their stator windings. This slight mismatch, or “slip,” between the motor’s speed and the current frequency is what sets asynchronous motors apart from synchronous motors. This slight slip between the rotor and the stator’s magnetic field makes the asynchronous induction motor well-suited for highspeed applications. AC induction motors are known for their durability, cheaper cost to produce and robust performance,

even though these motors may not be as efficient as PMSMs.

Both types of MGUs have unique advantages, but PMSMs have become the standard due to their superior efficiency, especially as hybrid technology has evolved.

MGU testing will involve using a scan tool for diagnostics, to check parameters sensor operation, data, and DTCs. If there are DTCs that direct us to test the MGU stator and its three phases (U, V, W), it can be specifically tested for insulation and conductivity faults. To check the insulation of the stator windings and cables, the Megohmmeter is needed. This special tester will send a specified voltage into the circuit during testing (special attention to proper POE and safety is needed) and most manufacturers will provide specifications. Hyundai provides a specification of greater than 10 megohms (abbreviated MΩ), when testing the insulation of the stator windings. (Note: 1 megohm equals 1,000,000 ohms.)

To test the resistance of the stator’s three phases another special piece of test equipment is going to be needed: the highly accurate Milliohm Meter. This meter will be needed to ensure that the resistance values of each leg are approximately the same and within specifications, and it can also be used to check the HV cables and connections. A conventional Digital Multi Meter (DMM) cannot measure the small resistance values that verify that electrical connections are clean and properly tightened. The Milliohm Meter measures the resistance in the 1/1000th of an ohm (1 mΩ = 0.001Ω. Note the lowercase m).

When testing the stator windings, we

typically would be checking the resistance of the three phases, between each interphase winding connector (U–V, V–W, and W–U), as directed by the diagnostics. Toyota provides a specification of below 135mΩ at 68 degrees Fahrenheit with no more than 2.0mΩ difference between stator legs.

For example, when testing a stator on a Toyota Prius MGU, the following would be good test results with the tests being performed at 68 F:

Stator Resistance Measurements:

• U to V 129.1 mΩ

• V to W 128.9 mΩ

• W to U 128.8 mΩ

Calculated Differences: The resistance difference between phases is measured to figure out if there is an interphase short. This could be a copper-to-copper short.

• (U to V) – (V to W): calculated difference = 0.2 mΩ

• (V to W) – (W to U): calculated difference = 0.1 mΩ

• (W to U) – (U to V): calculated difference = -0.3 mΩ

All calculated differences are below 2 mΩ (i.e., the difference between the highest and lowest measurements should be less than 2.0 mΩ). In this example, the vehicle passes for both specifications (below 135 mΩ) as well as for difference calculation (‘Standard resistance’) between phases of MGU. (All ‘standard resistances’ are close and well below 2 mΩ).

In a hybrid engine, the resolver acts as a rotary transformer that provides essential information on the motor’s position, speed, and rotation direction. It has a rotor with a reference coil and two stator coils positioned at right angles. When the reference coil is powered, it creates voltages in the stator coils that change with the rotor’s angle, allowing the system to measure its exact position. An excitation circuit supplies a signal at 10kHz, 12kHz, or 15kHz to power the resolver. As the rotor spins, changes in the air gap between the rotor and stator alter the signal, which a resolver-to-digital circuit then reads to calculate

the angular position. Three separate coils are used in the resolver. They are typically labeled A-B-C or Excitation (A), Cosine (B) and Sine (C) in wiring diagrams. These three coils will be used for distinct rotor information detection. Coil A will be used for rotor speed detection, Coil B will be used for detecting the rotor position, and Coil C will be used to detect the rotor direction of rotation. Scope testing is often the best method to test these circuits and there are special tools and learning procedures that need to be followed if a resolver sensor is to be replaced.

A DC-to-AC inverter is responsible for converting high-voltage DC from the vehicle’s HV batteries into three-phase AC, which will power both the PMSM and AC induction motors. The DC-to-AC inverter operates under the control of the vehicle’s Electronic Control Module (ECM) or Hybrid Electric Vehicle (HEV) management module. It will use six insulated-gate bipolar transistors (IGBTs) to regulate current flow. The IGBTs direct current from the battery to the stator windings, energizing the stator coils to create a magnetic field that drives the rotor, ultimately powering the wheels. Some hybrids may use a boost converter. The boost converter on some Toyota hybrids, such as the second- and third-generation Prius, is essential for stepping up and down voltage levels to improve motor performance and battery charging. The boost converter raises the HV battery’s nominal DC voltage of 144V to a maximum of 520V when needed, enhancing motor efficiency and extending the motor’s RPM range. It can also reduce the motor generator’s output voltage to match the requirements of the HV battery, allowing efficient energy storage during regenerative braking or power generation.

In addition to powering the vehicle’s AC motors, the DC-to-AC inverter can also convert the alternating current generated by the motor generators back into DC to recharge the HV batteries. Each IGBT in the system has a parallel diode between the collector and emitter, forming a rectifier

bridge. During regenerative braking, this bridge converts AC from the motor into pulsating DC to recharge the high-voltage battery. When the vehicle slows down, the ECM or HEV management module will turn off the IGBTs, allowing the rotating crankshaft to turn the rotor in the electric motor, inducing AC voltage in the stator coils. The six diodes then rectify this AC into DC to recharge the battery. Regenerative braking further helps by making the motor function as a generator, creating a driveline load that slows the vehicle while recharging the battery pack, with braking force being smoothly blended by the drive motor inverter and brake control modules.

The vehicle’s ECM or HEV management module will continuously check the DCto-AC inverter’s current sensors to find any

sensor malfunctions. Potential issues could include a faulty inverter/converter module, failed IGBTs, an open or shorted harness, or a poor electrical connection within the assembly’s circuit. Some hybrids offer the ability to evaluate the IGBTs using the Megohmmeter to measure resistance. Certain Toyota models provide an accessible cover over the IGBTs for testing. When assessing an IGBT on a Prius, a good IGBT will test between 18-19 megaohms. Anything more than 19 megaohms is considered defective.

The ECM or HEV management module will also keep track of the current in each phase of the MGU’s stators to spot any issues. Since the motor generator’s phase circuits are connected, each phase should carry a similar amount of current. The ECM or HEV/EV management module

uses calculations to check the accuracy of the phase current sensors. If the sensors for the U-V-W phases show similar current values, the total difference in current flow between phases should be close to zero. If there’s a significant difference in these values, a DTC will be triggered.

The ECM or HEV management module will also be looking at the temperature of the drive motor, DC-to-DC converter, DCto-AC inverter, and other components. These sensors can generate DTCs and in some cases can be serviced. But if the drive motor temperature sensor goes bad or is damaged on a 2018 Toyota Highlander, the entire assembly (traction motor/transaxle assembly) needs to be replaced as it is not serviceable separately.

Maintaining today’s hybrid systems requires regular checks and specialized care for the best performance and longevity. The cooling system, which includes a dedicated circuit for high-voltage components like the battery, MGU, and inverter, must be routinely inspected for coolant levels, leaks, and flushed as recommended. Since

THIS SCREENSHOT shows some of the data that is available to look at for the DC-to-DC converter. Note the 14V power module (DC-to-DC converter) setpoints, in percentage and voltage and the low voltage current information.

hybrid cooling often uses a non-conductive coolant to protect sensitive electronics, using the correct coolant is essential to prevent overheating and costly repairs.

The lubricating system also plays a critical role in hybrid performance, with specialized lubricants needed to handle high temperatures and start-stop cycles typical in hybrid powertrains. Regular oil level checks, fluid cleanliness, and adherence to recommended oil change intervals help reduce wear on electric motors and mechanical parts.

In summary, the hybrid motor generator, along with its associated systems and components like the DC-to-DC converter and the DC-to-AC inverter, plays a pivotal role in modern hybrid vehicles. By providing dual functionality as both a motor and generator, it enhances efficiency, reduces emissions, and improves energy management. Understanding and maintaining these systems is essential for technicians aiming to ensure the reliability and performance of hybrid vehicles. From routine diagnostics to specialized testing for components like PMSMs and AC induction motors, thorough knowledge and the proper use of tools are vital for efficient repairs. As hybrid technology continues to evolve, staying up to date with these complex systems will empower technicians to provide better service and keep these advanced vehicles running smoothly and efficiently on the road.

is a

professional at CARS Inc. in Oshawa with 40 years in the automotive industry. As a skilled technical writer and training developer, he holds licenses in both automotive and heavy-duty vehicle repair. Jeff excels in TAC support, technical training, troubleshooting, and shaping the future of automotive expertise.

The Proof Is in the Pudding

Chasing driveability concerns means pursuing the complaint. But unless you want a “comeback,” you had best find the cause, that’s a given. However, being efficient in this process is a bonus.

BY BRANDON STECKLER // Technical Editor

ALL TOO OFTEN a client brings his or her vehicle to us to rectify a driveability concern. Although we become very familiar with the symptoms of many driveability concerns over time, the root causes of these concerns can vary widely.

With the vast array of years/makes/ models and engine configurations out there, it’s no wonder that so many technicians face “comebacks.” There is just so much to learn and unless you have a game plan, you’ll find yourself shooting from the hip, and the odds of long-term success are not in your favor.

THE DATA DOESN’T LIE

WELCOME BACK TO ANOTHER EDITION OF “THE DATA DOESNT LIE,” A REGULAR FEATURE, WHERE I POSE A PUZZLING CASE STUDY.

You need to employ tried and true testing techniques. And to do that, you must become familiar and comfortable with those tests, as well as understand the results of the tests. I can’t think of a better tool or testing technique than employing exhaust gas analysis. The reason? The test technique applies to all internal

combustion engines out there. This is due to the chemistry involved.

Today’s Subject Vehicle

FIGURE 1 The results of the exhaust gas analysis reveal several clues that act as puzzle pieces, if you know how to interpret the gases. HCs (Hydrocarbons) are unburnt fuel. There are over 5,000 ppm (part per million) indicating that leftover fuel is in the exhaust stream. NOx (Oxides of nitrogen) are dangerous gases that occur in abundance when temperatures exceed 2500 degrees F. These appear to be in control. CO2 is an indicator of engine efficiency. A healthy engine typically yields about 15%. This engine is not performing well. Finally, normal engine combustion and a functioning catalyst should use almost all the oxygen that entered the engine. This is clearly not the case, here.

A 2008 Mazda 3, with a 2.3L engine entered the shop with a complaint of rough-running and an MIL illuminated. The DTCs were scanned and stored was only a P0300 (“Random misfire detected.”) Upon questioning the customer, the driveability concern only seemed to surface upon cold-starts. The vehicle was in another shop recently, for replacement of the timing chain and related components. The vehicle indeed left the previous repair facility in good running condition. No driveability symptoms were present after that repair.

The decision to employ a five-gas analyzer was made. This test offers a tremendous amount of information simply by measuring and analyzing the exhaust gas content, right at the tailpipe. This test revolves around science (chemistry, to be

SCAN TO READ MORE ARTICLES LIKE THIS

TECH CORNER

precise) and we can’t change what science proves. This means we can rely on the test results no matter which internal combustion engine is being evaluated, or the fuel being used.

The Results Are In

Capturing the exhaust gas while running the vehicle through a cold-start, the driveability symptom surfaced. As expected, the fault only occurred when cold and in open-loop. As the engine warmed and

closed loop occurred, the better the performance was exhibited. The gases were analyzed, and the results were reviewed (Figure 1). Please see the results below:

Hydrocarbon (HC) = 5342 ppm

Carbon Monoxide (CO) = 0.24%

Carbon Dioxide (CO2) = 7.3%

Oxygen (O2) = 9.7%

Lambda = 1.30 (per calculator)

A Logical Experiment

After evaluating the gas analysis, a

decision was made to introduce propane, a vaporized/atomized hydrocarbon (Figure 2). The vehicle was allowed to cool, and the engine was restarted to exhibit the fault. The propane was bled into the induction system in a controlled fashion and the captured exhaust gases were analyzed again (Figure 3).

Hydrocarbon (HC) = 380 ppm

Carbon Monoxide (CO) = 1.13%

Carbon Dioxide (CO2) = 12.9%

Oxygen (O2) = 1.8%

Lambda = 1.03 (per calculator)

The Data Doesn’t Lie

With all the information in front of us, and the desired information not yet obtained, we are faced with deciding how to proceed. Here are some bullet points of what we know to be factual, and I will ask all of you, diligent readers, for your input on what they mean to you, collectively:

• MIL illuminated / DTC P0300

• Engine runs rough at cold start-up (open-loop)

• Engine runs normally when warm (closed-loop)

• Exhaust gas analysis performed/ results improved with propane enrichment

Given this information, what would you do next?

1. Replace spark plugs and/or COPs.

2. Inspect timing components.

3. Evaluate fuel delivery system.

4. Decarbonize induction system.

BRANDON STECKLER is the technical editor of Motor Age magazine. He holds multiple ASE certifications. He is an active instructor and provides telephone and live technical support, as well as private training, for technicians all across the world.

Solved: Rough Running 2018 Ford Escape

From December 2024, Motor Age

BY BRANDON STECKLER // Technical Editor

What would you recommend doing next, given the data bullet points in last month’s challenge?

1. Inspect valve lash.

2. Decarbonize induction system.

3. Treat crankcase for stuck piston rings.

4. Replace camshafts for decoupled CMP reluctors.

Congratulations to those who chose answer No. 1! The valve clearances were measured, and several of them (including

cylinder No. 3 exhaust valve) were found to be too tight, creating the excessive overlap and reducing the manifold vacuum. This led to the speed-density fueling strategy over-fueling the cylinders and was the cause of the negated fuel trim.

The rough running condition was also attributed to the excessive valve overlap as the affective induction stroke of cylinder No. 3 was reduced because the cylinder was drawing in inert exhaust

Answer No. 2 is incorrect. Although a heavily carboned induction system could reduce manifold vacuum, the effected cylinders would tend to experience a worsening symptom with acceleration, as restrictions create pressure drops that intensify with flow.

Diagnostic Problems?

Diagnostic Problems?

Answer No. 3 is incorrect as well. Stuck piston rings would reduce manifold vacuum, cause a speed-density fueling strategy to over-deliver, and ultimately drive fuel trim numbers down. However, the relative compression pattern would’ve indicated lower starter load, not the steady 170 Amps that is visible in the capture. Besides, no smoke was exhibited leaving the tailpipe and no other evidence of oil consumption were present.

Answer No. 4 is incorrect as decupled CMP reluctors may allow a CKP/CMP correlation waveform to appear in time, however the in-cylinder pressure waveform capture would’ve demonstrated a shift in cam timing, which is not apparent. The most logical answer is to inspect the valve lash.

Did you know that internal combustion engines in hybrids were different?

BY CRAIG VAN BATENBURG

THE REASON WHY HYBRIDS WERE FIRST introduced to America in 1999 had everything to do with the internal combustion engine (ICE). Well, not the ICE itself, but the gasoline we put in the tank. Using hybrid technology 25 years ago we could have doubled the average fuel mileage so we would have more time to solve the climate problem. We did not do that. Carbon neutral liquid fuels can be made, but at a high cost. If we did that, then the ICE would be something we could live with, but that

is not feasible. The cost to produce close to zero carbon fuel is high. It also might impact the amount of food crops we eat, so other ideas have been developed. To get to an “Almost Zero Carbon” world, we must find other ways to travel. In terms of light duty transportation, the hybrid was the answer a couple decades ago and the internal combustion engine was part of that research.

Here are some examples of internal combustion engines sold in the USA.

What made them burn less fuel and still have the power needed to propel a car? In other words, how did a little gasoline engine act like a much larger engine?

James Atkinson invented a new type of gasoline engine in the 1880s, commonly known as an “Atkinson Cycle.” (Figure 1). It used valves, a camshaft and a connecting rod that changed lengths to produce four piston strokes for every one revolution of the crankshaft. Check online for this and watch the piston move at different

speeds during its rotation. The intake and compression strokes were significantly shorter than the expansion and exhaust strokes. These odd engines were produced and sold for several years by the British Engine Company over a century ago. James Atkinson also licensed production to other manufacturers, but this type of engine never caught on. Today, that exact ICE design is used by Honda in a generator called “Free Watt.” Because of Honda, a real “Atkinson Cycle” engine does exist today. If an actual Atkinson Cycle engine were to be used in a modern car, the crankshaft would not survive the repeated RPM changes and stress of shifting. The Honda “Free Watt” engine (Figure 2) operates at one speed and is a 166 cc, single cylinder that runs on natural gas. The little Honda engine is used as a generator for homes and also heats the house and provides hot water.

LIVC

Contrary to what you may have seen or heard, a real “Atkinson Cycle” engine is not used in any motor vehicle sold today. LIVC stands for “Late Intake Valve Closing.” It is the valve train and induction system that mimics, to some degree, what the Atkinson system was doing.

LIVC is used in many, but not all, hybrid and plug-in hybrid models. LIVC is also used in some conventional cars and trucks. We will use “LIVC” and not “At-

kinson Cycle” when referring to these gasoline engines.

When Toyota was creating the Prius in the early 1990s, one big advantage allowed them to develop a new concept based on the old “Atkinson Cycle” engine. Toyota had designed all their transmissions with a powerful electric motor (M/G2) inside the transmission (Figure 3) that combined with their “LIVC” ICE, powered the wheels with lots of low end torque.

How Toyota employed LIVC is simple in operation. It is always a twin cam engine as it needs to vary the intake valve(s) timing. When used in Toyota/Lexus vehicles the timing of the opening and closing of the intake valves is controlled by the Toyota-designed VVT-i system. During the compression stroke, the intake valve is held open. (Figure 4). Compression does not happen until the intake valve closes, or all valves close. While the intake valve is open during the compression event, the mixture is pushed back into the intake manifold. You will note that the intake manifold has a chamber, or bellows, (Figure 5) formed into the manifold allowing a space for the mixture to collect. At some point in the compression stroke the intake valve(s) will eventually close and then the mixture will start to compress. During this compression stroke some of the mixture moves into the intake manifold to reduce pumping losses. Pumping losses represent the

power lost when the engine rotates during periods of high vacuum. LIVC changes the volume, or displacement, of the cylinder and also supplies a charge of fuel and air for the next cylinder in the firing order. These engines have a high compression ratio number but operate at a low compression ratio most of the time. They also perform best with low-octane fuel, something that is not characteristic of high-compression engines. The LIVC engine allows for a more efficient operation, but sacrifices were made in the total output of the engine. The ICE can run with normal displacement when the intake valves close earlier, but

this is not needed at cruising speed. This action provides for more power output but at a cost. Because the VVT-i system responds to operating conditions, the displacement of the engine changes accordingly. The VVT-i system is managed by the PCM, and with that control, the intake valves can change quickly (within a range of 40 degrees or more) depending on the model. The PCM adjusts valve timing according to engine speed, intake air volume, throttle position, load, and water temperature. In response to these inputs, the PCM sends commands to the camshaft timing oil control valve (OCV). The VVT-i controller is located at the end of the intake camshaft, like most systems. The PCM controls the oil pressure sent to the controller. A change in oil pressure changes the position of the intake camshaft and the timing of the intake valves. The camshaft timing OCV is duty cycled by the PCM to advance or retard intake valve timing.

An aerodynamic vehicle with low weight and low-friction-producing components will get you farther on the same amount of liquid fuel. In addition to controlling the VVT-i system, the vehicle’s PCM also controls the fuel injection timing and the ignition system. Inputs from numerous sensors are used to optimize the ICE in

order to provide maximum fuel economy. Starting in M/Y 2004 the Prius used an air/ fuel sensor rather than a conventional oxygen sensor. The ETCS-i (Electronic Throttle Control System with intelligence) system controls the position of the throttle plate. There is no cable between the accelerator pedal and the throttle plate. The eCVT (electronically controlled constantly variable transmission) requires precise control of the planet carrier inside the planetary gear set. More about this will be explained when you study a Toyota eCVT. If the throttle on a Toyota (or Ford, as they use a similar system) hybrid cannot be perfectly controlled, serious transmission damage will result. The PCM calculates the proper throttle opening and sends, via a CAN bus, the signals needed to open and close the throttle plate.

The Prius gasoline engine (Figure 6) was 1.5 liters from M/Y 1998 to 2009. In M/Y 2010 a 1.8L was installed. Even though the displacement increased, so did advancements in fuel economy, performance, and exhaust emissions. One note here: the 1.5L has a tendency to burn oil at 150,000 miles even if the oil changes were done on a reasonable time frame. Today, many car owners do not get oil changes on time, and sometimes use poor quality oil. Trying to save

money, the engine suffers. To counter these problems, most independent hybrid repair shops use a de-carboning system to dissolve the carbon on the piston rings that tend to be the reason for the oil consumption.

Strange Gas Tank

The country we live in has very strict regulations in regards to gasoline evaporating into our atmosphere. Japan is not as concerned, so Toyota needed new technology in that area as the ICE did not run all the time while the Prius was in motion. To accomplish that, the fuel was stored in a flexible plastic/rubber compound called a “bladder,” having a similar function as a human bladder. Toyota added this bladder in the steel fuel tank of the Prius generation I and II — M/Y 2001 to 2009 (Figure 7). From the outside it looks like a typical gas tank. It is sold as one unit. The engine and oxygen sensor test the air gap between the bladder and steel tank. It is looking for the presence of HC in the air sample from between the bladder and tank indicating an internal fuel leak. The best way to know what is going on is to use an enhanced scan tool looking at data and codes. Tech tip: if you get a code for a leaking bladder, before replacing the gas tank, make sure the owner does not have the

habit of “topping off” when refueling. If he or she does, gasoline can get between the tank and the bladder, causing that code. Fix the customer or the job will come back. It is no secret that Toyota has had problems with first generation bladder tanks.

VW Jetta HEV

The ICE in the M/Y 2013 Jetta HEV is a 1.4liter direct injection turbocharged four cylinder (Figure 8). It is attached to a seven-speed dual-clutch transmission with a 20-hp electric motor installed between the ICE and transmission. Total system output is 170 hp (125 kW) and 184 lb-ft (250 Nm) of torque, the latter available from only 1,000 rpm. Considering the Jetta Hybrid requires premium gasoline, the fuel mileage is important as it costs more for fuel than most other HEVs. The Jetta Hybrid is equipped with a TSI “turbocharged stratified injection” engine with a single turbocharger.

To make this ICE ready for hybrid duty,

VW modified the engine block with an integrated secondary air channel, hybrid oil passages, and hybrid coolant passages. The crankshaft needed splines for connection to the HV electric motor and the cylinder head used four valves per cylinder. It had an integrated exhaust manifold. That exhaust trick was done by Honda in the original Insight back in 2000. The intake and exhaust camshaft had adjustable timing and they were belt-driven. VW had both electrical and mechanical coolant pumps. The positive crankcase ventilation (PCV) system is on the front of the engine block. The intercooler is liquid-cooled. When vacuum is needed, and the ICE is off, VW added an electric vacuum pump.

VW Turbo Boost

Because the VW 1.4 engine performance is good without the turbo and using “boost” contributes to fuel consumption, the use of the boost is limited. It will not boost if

the kick-down position of the accelerator pedal is activated in position “D,” or when there is strong acceleration at selector lever position “S” and also when the “Tiptronic” shift gate is engaged.

A Mode Without Turbo

The HV electric motor is adding torque to the drivetrain, along with ICE, and the total torque from both may reach a “maximum torque” that the Dual Clutch Transmission (DCT) was not designed for. The Jetta HEV will disengage the Turbo if the DCT could be damaged. There have been software updates and transmission problems as sociated with this model.

In summary, the evolution of gasoline engines has been going on in the hybrid world for over 25 years. When changing oil, pay attention to the “Fill” line on the dipstick. Many technicians will guess about the amount of oil. I often ask in class, how many quarts equals 3.5 liters? The answer is not four quarts. It is 3.7 quarts. That 0.3 quarts overfilled is a problem for a LIVC engine. As you study more about hybrids, don’t forget many have a unique engine. As always, use quality lubricants, deionized antifreeze, OEM equivalent parts — and service information. The little things matter. I want to thank all of the automotive technicians who have supported ACDC since our first hybrid class 25 years ago when Honda shipped me an Insight from Japan.

CRAIG VAN BATENBURG is the CEO of ACDC, a hybrid and plug-in training company based in Worcester, Mass. ACDC has been offering high voltage classes since 2000, when the Honda Insight came to the USA. When EVs were introduced in 2011, ACDC added them to their classes. Reach Craig via email at Craig@ fixhybrid.com or call him at (508) 826-4546. Find ACDC at www.FIXHYBRID.com.

AUTOMOTIVE PRODUCT GUIDE

Includes built-in sweat wipe

The Milwaukee Tool Anti-Vibration Work Gloves, No. 48-73-8772, are designed to be long-lasting and offer full hand vibration reduction, decreasing wearer fatigue and the long-term health risks associated with prolonged vibration exposure. The gloves include reinforcements in high-wear areas such as the fingertips and palms and SMARTSWIPE technology in each glove’s fingertip and knuckle, making them compatible with touchscreens. They are made with a breathable lining and feature a built-in terrycloth sweat wipe to keep users’ hands dry and comfortable. They are available in sizes S through XXL.

Captures temperatures on 3.2” screen

The Teslong Thermal Imaging Camera, No. TTM260, is a compact and portable device designed for visualizing temperatures ranging from -4 to 752 degrees F. This device detects thermal, or infrared radiation, and translates it into color, helping you see temperature contrast even in poor lighting and without contact. The TTM260 not only assists with locating hot/cold areas but also has a built-in (Class II) laser rangefinder to measure the distance between the device and any target. Users can capture photos with a short press of the trigger button and videos with a long press.

Connects to smartphone as image generator

The HD Video Borescope, No. 481224/4AF, from Hazet, features a 360-degree swiveling probe and is 1m long and 3.9mm thin. The borescope is designed to get into areas otherwise hidden from the user. With a focus range of 5mm to 100mm, this tool can detect damage as small as hairline cracks or grooves. The joystick feature can direct the camera head in any desired direction. With no display unit of its own, the borescope can be connected to a standard smartphone as an image generator and storage unit. The borescope is IP67 waterproof with a temperature operating range of -20 degrees C to 70 degrees C.

Features integrated AI chat support

The OPUS IVS DrivePro 2 Plus is designed to be a diagnostic platform that the company says offers 100 percent brand coverage. Users can access their own OE software through MyCarDAQ or pre-existing OE applications through the tool’s Farsight mode. The DrivePro 2 Plus allows users to access direct communication with brand-specific master technicians as well as integrated AI for instant repair suggestions and troubleshooting. It features up to 16GB of RAM, an Intel Core i3 or i5 processor, and is 5G capable. It comes in a rugged, drop-tested body.

Features maximum charging rate of 120A

The PRO-LOGIX 12/24V Flashing Power Supply and HD Battery Charger, No. PL6850, from Clore Automotive, provides high current stable power for advanced module reprogramming on late model ICE, hybrid, and electric vehicles. It can properly charge a variety of lead-acid battery types and manage depleted and sulfated batteries. It features an automatic charging mode for easy operation, 120A max charge for speedy fleet service, and precise voltage control in 0.1V increments. It keeps voltage ripple to a minimum and uses rapid load responsive technology to minimize voltage drops to deliver clean power that will not disrupt reprogramming. The PL6850 comes with extra-long 13’ cables to reach all vehicle starting points.

Rolls out for easy access

The 13-1/4” 15-Pocket Roll-up Tool Bag, No. 98 99 13 LE, from KNIPEX Tools, is a convenient way to store and transport tools thanks to its roll-up design. A double side release buckle makes it easy to open and close the roll, and the bag rolls out for quick access. It includes 15 individual tool slots, is made of polyester fabric, and measures 6” wide.

VIEW MORE PRODUCTS ONLINE

Comes with mirror, magnet, and hook attachments

The Innova Electronics 3381 AudioEnhanced Inspection Camera features a 2.8” LCD display and IP 67 waterproof camera capable of capturing images and videos with 720p native resolution and interpolated resolutions up to 1080p. The 39” semi-rigid camera cable has eight LEDs, which can be controlled with a touch of a button. Users can record videos with voice commentary, capture stills, flip the screen, and zoom up to 2x. The camera includes a 4GB TF card and magnet, hook, and mirror attachments for the probe.

Venom® HP

Features SteadyPin probe tips for secure connections

The Electronic Specialties 180VM LOADpro Dynamic Test Leads and Volt Meter allows users to instantly load a circuit to see if current can flow and was designed specifically for finding wiring faults in vehicles, including high corrosive resistance, shorts to ground, and open circuits, with the press of a switch. The kit includes a portable volt meter, eliminating the need for a multimeter when performing quick jobs. The leads feature SteadyPin probe tips that allow the probe to sit firmly on a male AECM or connector pin to ensure a secure connection. The LOADpro leads can permanently replace existing test leads.

Lifts EV batteries and heavy components

Venom HP generates Magnetic induction™ heat that releases ferrous metal from rust, corrosion and thread lock compounds without the dangers of

The Air-Hydraulic Lifting Table, No. LT35A, from Rotary Lift, offers side-toside tilt alignment with fore and aft lift adjustments while under load. The platform can be adjusted to fine-tune positioning with swivel locks on both sides for additional safety. It runs on shop air-hydraulic operation, so no electrical power is needed to operate it. Its pushbutton pendant control offers easy and comfortable use while providing the technician the ability to move around and have a clear view of the workspace. Additionally, the table has a 3,500lb capacity, is secured with air-released mechanical locks, and has 360-degree “low friction” casters on each wheel.

Includes 2 batteries, charger, and carrying case

The Stubby Impact Driver Kit–Green MCL16SIDKG, from a compact design with an overall length of less than 5” while delivering up to 300 ftlbs of breakaway torque with its brushless motor. The driver is ideal for accessing and operating in tight spaces and uses a 1/4” hex opening for quick and easy bit chang es. It also includes two 16V 2.5Ah Li-ion batteries, a charger, and a carrying case.

MOBILE APP

N0W AVAILABLE

Whether in the repair shop, office, or lobby, you can now look up and order parts wherever you are, from any mobile device. Simply search for O’Reilly Pro in your app store!

FEATURES:

• Full parts catalog

• Available in English and Spanish

• Ability to place orders from your mobile device

• License plate scan to VIN

• VIN Scan

• Send quotes via SMS or Email

• Connects to OReillyPro.com for transitions from mobile to desktop

• Search functionality

• Real time product availability

SCAN HERE to download for both IOS & Android

DOWNLOAD O'REILLY PRO

IN THE APP STORE TODAY

TECHNICAL SERVICE BULLETINS

JEEP NO REAR DEFROST

This bulletin applies to 2018-2022 Jeep Wrangler vehicles equipped with rear window defrost. The rear window glass left or right side defrost solder terminal may be detached from the defrost grid. The rear defroster electrical connector is a one-time use design. If it comes loose, or is removed for any reason, it must be replaced.

New rear defrost connector is available as P/N 68499001AA. (Photo: Jeep)

LEXUS THE RIGHT BOLTS

As with other import vehicles, some 20212024 Lexus vehicles feature hub bolts in place of hub studs/nuts to fasten wheels to hubs. If non-compatible fasteners are used, the wheels may loosen and come off. Shops that don’t have experience with wheel bolts

need to pay special attention to avoid problems. When replacing wheel-to-hub bolts, several bolt seat styles are available. It is critical to use only wheel bolts that match the requirements of the wheels. Styles that exist include one-piece bolts that feature a spherical seat, bolts with a spherical washer, one-piece bolts with a tapered seat, bolts with a tapered washer and bolts with a flat washer. None of these styles are interchangeable. Do not assume the bolts are interchangeable even if the mating surface shape is the same. Always consult the parts catalog for correct hub bolts for the specific vehicle. (Photo: Mitchell 1)

LINCOLN EVAP MESSAGE

Some 2017-2018 Lincoln MKC vehicles equipped with a 2.0L gasoline turbocharged direct injection (GTDI) engine and built on or before Sept. 18, 2017, may exhibit a MIL on with DTC P04DB (crankcase ventilation system disconnected) in the PCM.

Reprogram the PCM to the latest calibration using IDS release 107.01 or higher.

(Photo: Lincoln)

MERCEDES-BENZ BRAKE CLEANUP

Mercedes-Benz emphasizes the need to clean the mating areas where brake discs mount to hub flanges during brake service work. They specifically recommend the ATE Teves Hub Cleaning Kit to remove all excess corrosion/scaling. Failure to remove corrosion or scaling may cause an excessive build-up which can create adverse forces that may result 9in brake vibrations/judder. (Photo: Mitchell 1)

BUICK AWD GROAN

This bulletin applies to 2020-2023 Buick Encore GX vehicles equipped with an L3T engine and M3F transmission. When in AWD mode, a groaning noise may be heard from

the rear of the vehicle. This condition may be caused by a slip/stick of the clutch plates. Make sure that the fluid is at operating temperature before draining by driving the vehicle in AWD mode. Replace the RDM lubricant with Dexron LS 75W90 (P/N 9986290). Bring the new lube up to operating temperature. Perform multiple figure eight or lock-steer maneuvers to work the lubricant into the clutch pack. Allow the vehicle to cool back to ambient temperature. If the moan/groan noise is still present, repeat these steps. This sequence may need to be repeated two to three times to reduce/eliminate the noise. If the concern is not resolved after three repeats, replace the RDM. (Photo: GM)

SUBARU

COLD WEATHER CRANK

This bulletin applies to 2020-2021 Subaru Legacy and Outback vehicles equipped with a 2.4L DIT engine and 2019-2021 Ascent vehicles. New programming files are available to address DTC P1160 and customer concerns of extended cranking in cold temperatures. In rare cases, if the engine is switched off in extremely cold weather, the throttle plate may not return to the proper position. If this occurs, the next time the engine is started, the ECM detects the throttle plate as out of position and interprets the value as a failure, resulting in the extended cranking

and the DTC. The throttle position sensing control has been optimized to avoid this issue. (Photo: Subaru)

BRONCO STABILIZER BAR

Some 2021-2023 Ford Bronco vehicles equipped with a factory front stabilizer bar disconnect may encounter a Sta-bar Disconnect Service Required message in the IPC and an illuminated warning light, with DTC(s) stored in the CHCM (C103A, C1A99, C1B03, C1B07, C1B14 and/or B1A67). To correct the condition, follow the service manual procedure to address water intrusion and reprogram the CHCM using the latest software version of the FDRS scan tool.

1. If water or corrosion is present in any connectors C1295A, C1295B, C1294A and/or C1294B, replace the front stabilizer bar disconnect harness and the front stabilizer bar disconnect. If no corrosion/water is found, apply electrical grease into all four connectors.

2. If water/corrosion is present in either side of connector C1415, replace the stabilizer bar disconnect harness and body harness. Apply electrical grease into connector C1415. If no water/corrosion is found in connector C1415, apply electrical grease to the connector.

3. If water/corrosion is found in connector C445, replace the connector with a service pigtail kit and the CHCM. Apply electrical grease into the connector. If no water/corrosion in connector C445 is found, apply electrical grease into the connector.

Reprogram the CHCM using the latest software. (Photo: Ford)

BMW CAMERA WOES

BMW notes that some rear view parking assist camera systems may exhibit conditions as follows:

Images for rear view camera and top view camera are swapped in the display.

There is a vertical line noticed and/ or camera icon is randomly located in the rearview image.

. Partial green border is seen around the image.

Trailer hitch alignment line does not line up (offset).

The screen is blank/black.

The issue may be caused by a software coding error in the ICAM control unit. Encode the ICAM control unit again after programming with ISTA 4.25.4x or higher. Multiple encodings of the ICAM control unit may be required. (Photos: Mitchell 1)

Why You Need a Portable Battery Jump Starter

Whether you’re going to pick up a car from a customer, taking an initial test drive, or conducting a post-repair road test, there’s always a chance of something going wrong. Maybe that “intermittent problem” pops up, or the car won’t start, or you get a flat tire – any of which can leave you stranded miles from the shop.

Save yourself the hassle and lost hours by throwing a portable 4-in-1 battery jump starter in the vehicle before you head out. Today’s lithium battery chargers are small and lightweight, making them much easier to grab and go than lead-acid battery models.

What’s included in a 4-in-1 power pack?

Battery Charger: The most obvious reason to carry this handy tool is to be able to quickly jumpstart a vehicle. Output varies among models, so choose one powerful enough for the types of vehicles you generally service. The JackPak Ultra2500A, for example, is a compact model that stands just three inches tall and weighs 6 pounds. In spite of its small size, it packs a big punch, delivering 2500 peak-amps of power. That’s almost double the output of other models in its class. The Ultra2500A can quickly start 12-volt cars and light trucks, as well as full-size SUVs and vans with gas engines up to 8.5 liters or diesel engines up to 6.5 liters. With a battery charger, you don’t have to wait for someone else from the shop to come and jumpstart or tow the vehicle. You can start it yourself and get back to work.

Air Pump: Inflate a flat tire or the spare in no time with a built-in air pump. Look for models that can deliver up to 150 PSI, with automatic shutoff and a clip-and-lock air chuck that fits standard valves.

Power Bank: Of course, the day you head out with a low phone battery is the day you get stuck. Wherever you wind up, a power bank ensures your phone and other mobile devices stay charged, keeping you connected. Look for models with USB ports that are compatible with any standard USB device and support Quick Charge USB 3.0 technology.

Flashlight: A bright LED flashlight can light up the work area as you change a tire or look under the hood. It can also serve as a roadside flare to warn oncoming traffic. LEDs mean the flashlight will stay cool and bright for hours on end. Look for models that offer a variety of modes, including bright constant light, high-intensity strobe, and SOS flashers.

Portable battery chargers aren’t just for consumers. They can be a valuable tool for protecting your time. Add one to your toolbox today.

NO. 157 Investing in the Right Tool

BY BRANDON STECKLER // Technical Editor

INVESTING IN THE CORRECT TOOL FOR the job is more than just buying one that suits your preferred price range. Taking into consideration the types of vehicles you see day to day, and the types of problems/systems you address should be the primary factors in choosing the tools you desire to equip with.

On this episode of The Trainer, Motor Age Technical Editor and master diagnostician Brandon Steckler discusses some of the strategies he suggests be implemented when deciding on which tools to invest in, and finding ones that best suit you and your shop’s needs.

It all begins with evaluating the types (years/makes/models) of vehicles you address day-to-day. Questions like “Do we specialize in a specific make?” “Are we more a Euro shop or do we tend to ad -

dress mostly domestic or Asian vehicles, or perhaps all three?”

It’s important to determine early what type of work you do as well. “Are we a full-service facility?” “Do we mostly perform diagnostics and driveability for other subletting shops, or perhaps provide mobile support solutions like programming/locksmith type services/ ECU programming and configuration?” Maybe you simply perform quick lube and service-type procedures.

All of these criteria and more can help establish some guidelines to pair you with the tooling that will not only serve you and your shop well, but will also prevent you from spending more than you need to, and without regret.

With a little help from PTEN Maga zine’s 2024 Scan Tool Spec Guide you