Some owners of 2013-2016 Buick Encore vehicles may complain about a bumpy feeling, a surge or an engine vibration while stopped at idle with the transmission in Drive and their foot on the brake pedal.
This condition may be caused by the transmission Neutral idle feature. When the service brakes are applied and the vehicle speed, throttle position and transmission temperature are within the calibration defined limits, the TCM commands the transmission to Neutral.
When the concern occurs, move the transmission shift lever to the manual position. Moving the shift lever to the manual position will prevent the Neutral idle feature from functioning. If the concern is eliminated my moving the shift lever to the manual position, it is caused by the Neutral idle feature and variation in the 1-2-3-4 clutch fiber plates. The 1-2-3-4 clutch fiber plates should be replaced. This is a kit that contains two clutch fiber plates. The 1-2-3-4 clutch piston should also be replaced at the same time.
The clutch plate kit is available as P/N 24273076. The clutch piston is P/N 24259453.
For diagnosis purposes, a typical Neutral idle bump is illustrated in the GDS2 snapshot shown below. When Neutral idle is activated, transmission ISS will nearly match engine speed. When Neutral idle is deactivated, 1st gear will be engaged and transmission ISS will drop to zero as long as the vehicle is stopped. The variation in the 1-2-3-4 clutch fiber plates create the variation in transmission ISS and the small spikes in the transmission OSS, These transmission OSS spikes cause Neutral idle to be commanded on/off/on/off as seen below creating the bump or surge sensation.
