a/f problem

[Otto J]

i was out tonight i have my full throttle set at 11.7 and it is always within 2 percent change , but tongiht it was cool out and now my a/f is down at 9.8 with no other changes?
anyone? no i leaned it out about 3 percent today and it stil is around 9.8 to 1 my egt was always around 1650 on an full pass but now it is 15.30 so it definetly is richer but why all of a sudden?
i am only concered hoping that the (so callled) probelm goes away and the car goes lean
thanks

 

[bobc455]

Did you record the run? I wonder if your MAP was reading higher than it used to. I wonder if you are bumping into some new VE values in the table because of the colder air (although you have a front mount already, so it's probably not likely that your intercooler was underperforming before).

Did you replace a clogged fuel filter so your fuel delivery system is better than it used to be?

Also, I would check out your ignition (plugs / coils), if there is a combustion problem in one cylinder maybe you are dumping some unburnt fuel on the O2 sensor.

-Bob Cunningham
bobc@gnttype.org

 

[bruce]

Originally posted by KLHAMMETT
i was out tonight i have my full throttle set at 11.7 and it is always within 2 percent change , but tongiht it was cool out and now my a/f is down at 9.8 with no other changes?
anyone? no i leaned it out about 3 percent today and it stil is around 9.8 to 1 my egt was always around 1650 on an full pass but now it is 15.30 so it definetly is richer but why all of a sudden?
i am only concered hoping that the (so callled) probelm goes away and the car goes lean
thanks

Where's your MAT sensor?.
If it's looking at ambient air temps, then that would do it.

 

[Otto J]

ill check the map on the run it was recorded and i just got home and made a pass just havent looked at it yet,as far as mat it is set 0 across the board so how could that affect it?
thanks

 

[TurboJim]

Because MAT is used in a SD calc

Can it be zero'd? I never even looked!

Yah, just looked. I still think it can affect the final SD calc.

 

[Otto J]

ya but seeing that mine is zero across the board should it have any affect on my car?

 

[TurboJim]

Well, I could be wrong but if the ecu goes, tps+map+rpm+cts+mat=ipw then it does matter.

I also think the mat comp is there in a table to be used as maybe fape type of trim...to enrichen over time as maybe the ic heat soaks.

Anyone know the deal here?

 

[Otto J]

well i figured it out, i added air temp to my dashboard last week, so when i was watching the log i saw that my air temp was -5.4
so i was like WTF so i pulled out the sensor an the center ws gone
and we all know what is next aftrer the air fliter THATS RIGHT
the TURBO so i had to file a few fins down a bit no bad though,and found the pieces in the intercooler, put a new sensor in, but decided to screw it in the intercooler for a more accurate reading and just to be safe added more fuel in the VE table and boy i added about 10% and was about 10% shy of being right
so make sure your air temp is reading correctly,and what doesnt make alot of sense is my air temp correction is 0 across the board,
but it is nice to no the temp of incoming air and with my COTTONS front mount it was always the same as out side temp, and to think i was gonna sell it
See Yaa Otto