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Lambda Testing by SM
Scott M writes:
>All of this data indicates to me, that rich Air/Fuel mixtures are only
>going to be detramental to the cat convertor if the HC levels start to
>skyrocket due to poor combustion/ignition system, otherwise, it appears
>that our European chip tuners have riched up the mixture beyond the 12.6
>to 1, max power range for some reason. More cooling from the extra fuel
>and reduced detonation are my guesses....
Couple of issues on the numbers. Nice report btw Scott.
A high CO value would indicate that in fact you have a lean condition, not a
rich condition. Given high CO readings something doesn't smell right. High
CO (and really high CO in some of your data) indicates a lean combustion,
since the lowest CO numbers would be acheived befor lambda of 1.00, and the
highest (and yours are really high), after lambda of 1.00. So, something is
going on, but what?
Could these high CO values indicate that combustion might be occuring
somewhere other than the combustion chamber? I think so. But not sure where
you are getting your fuel mixture values from.
Regardless, a bunch of us old v8 carb owners know, long term increase in HC
fouls plugs, so eventually you will have a misfire in your ignition system.
It only takes 1 plug of the 5 for HC to start a dripping, once that happens,
life gets complicated and expensive. Betcha a whole bunch of lawyers would
have a grand interest any technical explanation of raw HC's thru an exhaust
Looking at Fig 2-5 in Probst book shows that variations in "rich" air-fuel
ratios make little difference in power. Oppositely small differences in
"lean" air fuel ratios have a great effect on power.
Very interesting numbers you got Scott. I'd love to get those printouts to
explore them some more. I always read high CO levels to mean Lambda > 1.00
which is lean. Really high CO values, to me (assuming all other combustion
processes are intact) indicates that something isn't jiving between A/F ratio
read and the CO value. OR, there is more combustion going on than we make
think. Like NOT in the combustion chamber.
Audi has been known to put fuel injectors into exhaust manifolds, right Ned?
Hmmm, starting to see why.