Decades ago when we were involved in drag racing, we heard about a magical, mysterious device that would actually tell you the air/fuel ratio you were running. No more guesswork about jet sizes and metering rod settings, and no more coasting into the pits with the engine off for a visual plug reading (we looked for a nice chocolate brown right at the edge of fouling). But we were never able to afford one, so we continued our previous experimental approach to assuring a nice, fat mix of about 12:1.
Not long thereafter, our state instituted emissions inspection. We were astounded to see on big analog meters the actual amounts of HC and CO our car was producing. Was there a miniature chemistry lab inside the machine? Actually, yes there was in the form of an infra-red bench, the operation of which we won’t get into here beyond saying that it differentiates among the gases present on the basis of their absorption rates of infra-red wavelengths.
Download this whitepaper to read the full report.