This early AFR meter sort of “guesses” at the HC level.

Getting the most out of exhaust gas analyzers

May 29, 2020
All the scopes and scan tools in the world won’t tell you what’s actually being spewed out of that tailpipe. Here’s what a gas analyzer can do for you today.

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.  

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John Hitch | Fleet Maintenance
Skills stations were set up in the 225,000-square-ft. exhibit space in Cleveland's Huntington Convention Center.