Translator+, how much does 2% change your A/F?

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Six_Silver

New Member
Joined
Sep 10, 2003
Messages
212
Has anyone tried a back-to-back test of a change in A/F ratio either on the dyno or with a WBO2 when changing the WOT MAF settings by 2% or any % for that matter? I am curious to see how much of a change a certain % has on overall A/F ratio.
 
2%, more or less.

There are lots of factors though. The MAF tables in the chip may not be linear. The change might make injector duty cycle cross the 100% threshold. The discrepancy between commanded and measured A/F may not be linear.

Assuming that everything is linear, etc, then the formula would be ((100/(100+change))*100)-100. So +2% fuel will be -1.9608% change in A/F. That is close to -2%, but at +10% fuel it is more like -9.1% on A/F.

HTH,
Tom
 
Thanks for the explaination. I am running 83's and have lots of DC left.

I was just looking for some refrence to follow. If conditions have changed and a data logged pass shows something lean like 12:1, I was looking for a baseline adjustment to get it back into the low 11:1 range.



Boy do I wish I had a FAST setup.
 
In the 11.0 - 13.0 range 2% will change A/F by .25. This is a pretty coarse estimate, but considering all of the variables, it's close enough. Don't forget that to increase A/F, you remove fuel, and vice versa.

Tom
 
tminer-

Good info, thanks. I will be tuning the car on the dyno and would like to experiment for myself how much of an effect a certain percent will have on the overall A/F.

Thanks again.
 
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