CO% output vs. A/F

[JhwShark]

Another thread lead me to ask...
What is the correlation between CO% output readings vs. A/F. At smog tests we get our CO% measured and wonder what would 14.7:1 A/F = ?CO%. My engineering skills have wained over time but their must be a fairly direct correlation (some formula??)?

Why do I ask...I use a CO gage to check engine prior to smog testing but an installed gage may help me keep the car in top condition...though I drive it usually only when I will have a good road drive. I don't take it out to get the quick chore done.

Jon

[123quattro]

14.7:1 (or higher) will theoretically result in the lowest CO, as in none. You supposedly get complete combustion at stoich. Obviously that is not the case. However, if you are near 14.7:1 and have a working cat you should have basically no measureable CO emissions. Generally lean makes NOx, and rich makes HC and CO.

[MPDano]

Originally Posted by 123quattro

14.7:1 (or higher) will theoretically result in the lowest CO, as in none. You supposedly get complete combustion at stoich. Obviously that is not the case. However, if you are near 14.7:1 and have a working cat you should have basically no measureable CO emissions. Generally lean makes NOx, and rich makes HC and CO.

Great explanacation! Yeah, this is basically why I passed my Co and Nox. I was running super lean, but my car suffered at low rpms. Kinda sputtered.

[Normy]

Does someone have a WSM handy? I vaguely remember 1.5% with a certain vacuum hose pinched off. The procedure to properly set mixture is in the manuals.

N

[JhwShark]

Good stuff guy's...Thanks for the input so far.

BTW, WIkipedia has a good article on A/F at: http://en.wikipedia.org/wiki/Air-fuel_ratio

Jon