What does a stock evo run for air/fuel ratio? What should a approx. value should a evo run with intake, exhaust? My car is running from 14.8 ~ 15.1 or so.. Wondering if this is a normal value or is there something to worry about.. When it dips back to the lower 14 value kinda a stutter.

 

Using a Wideband O2 sensor?

14-15 is uber lean. Should be 11 or under at WOT.

 

daymn thats lean

 

Are you saying 14.8-15.1 at idle? or WOT?

 

First of all are you asking about normal driving or Wide Open throttle acceleration?

Normal Driving = Closed Loop operations
WOT = Open loop operations

During normal driving the ECU is set to keep the a/f ratio around 14.7 , it usually hovers around that area. When you are accelerating in such conditions that put your car in open loop mode then the stock tune for an evo I believe is low 10's.

 

+2

 

Yea im sorry didnt really specify what I was really asking.. I meant idle wise. This is according to my air/fuel ratio meter, not the wideband. Thanks so much guys damn you all are amazing at helping people!!!

 

Using a narrowband? Not accurate.

 

narrow band= fail. on a Wide band is ok.

 

14.7 is the desired (oem) afr at cruise and idle. It is going to swing about a half point in both directions just as a result of the narrowband switching design.


thank god you aren't asking about wot afr, there are more answers to that than bandwidth