I am wondering how much difference should be found between the ECU fueling map and the AFR read with a WBO.
Is a stock car meant to be real real close to its specified AFR, or is there a typical wider tolerance ?
Of course, the ECU will adjust the AFR regarding coolant temp, etc. but I guess it will not change that much in normal and warmed up engine condition.

I think something like 9.3:1 becoming 10.3:1 at high rev & high load should not really be acceptable (purely speaking of error margin, not raw AFR).
I would have said that something like max. +/-0.5 air volume could be within right bounds.
But in fact, I have quite a lack of experience with this kind of measuring, so I would be glad if I could get any input on this...

Thanks for your concern

Fabrice.

 

On phase 2 JECS I don't use the map values as absolute, just a starting point in reference to WB. And the more mods you make to the car, the more you can ignore the AFR value in the maps. I've never reviewed it on a stock unmodified car, maybe it's correct then.

Richard

 

Thanks for the answer
I guess I will have to put my car back in the closest stock-like configuration possible to get a better clue

Fabrice