just installed a tbe from logic performance this weekend. Had a CEL for a day but that went away after resetting my ecu. but now i noticed that my afrs are very erratic. Under normal driving/ cruising...they seem pretty normal and consistent around 14.5...but under heavy acceleration it drops down to ~10....when the car is in gear and im not stepping on the gas they jump to ~20...is this a serious problem?? granted i never paid attention while i was stock and im sure that my apex'i tt is not the most accurate thing to go by but im just worried i have a problem here....is this something that an ecu flash can fix and can it wait about a month until i can afford to get one? or is this something serious that i need to look into asap. thanks

 

thats normal bro... it goes rich as hell under wot up top and leans out when crusing.

 

That's not erratic; that's the difference between closed loop and open loop. At idle, you should see atmospheric pressure, which is 14.7. At WOT, you will see it drop to 10, because the factory tune is rich as hell. Your TT is just reading the narrowband O2 volts and converting it to wideband numbers. It is expected that you would see 10s at WOT.

 

There's a subtle mistake here. At low load, AFR should be near _stoichiometric_ for gasoline combustion, which is 14.7:1 (other fuels are different). Coincidentally, this is close to standard pressure (1 atmosphere), 14.504 PSI.

Sorry to be pendantic, but this is sure to confused some people.

d

 

Yes, thanks, stoichiometric is correct, but I bet people get more confused by the use of "pedantic" than the difference between atmospheric/stoichiometric.

 

Not sure if it's normal but I have a apexi TT and I'm seeing the same thing. At cruise it would be 14.3-14.5. At idle it would be the same but it sometimes go to 16 or 17 and then back down. WOT it goes to around 10. Car is basically BR S4 with custom tune dynoflash.