[ZR2_S10]

Ok, so my understanding (which could be WAY off) is that the long term fuel tirm is an 'average' of the short term fuel trims.

How is it that if I adjust the fueling (afc / iccu / etc) that I can get the LTFT's to around -5 (they are around -22 at 100%) but the short term fuel trims show +3 to +5?


If I remove so much fuel that the ltft's go to 0, the car starts to stumble at idle, starts to sound like its got a nasty cam in it.

I richened it back up at idle, just so it runs smooth, but at cruise, it feels sluggish (at -1 to -5 ltft's) but it pulls hard with -10 ltft's.

Any ideas?

 

[ZR2_S10]

No one knows huh?

 

[JasonGS]

Just so you get a response, I have no clue what's wrong with your car. Your understanding is the same as mine....

 

[VIN7]

Do you have a cam?

STFT do lead to a LTFT average, but keep in mind that there are LTFT cells. These cells are specific for a different driving condition (depending on MAF and TPS values) idle, decel, medium load, high load, light load I always see cell 3 (high load) when at WOT, however cell 3 "learns" its LTFT at >25% TPS and >.4 gps (i.e. a part-throttle condition). Since it has nothing to do with WOT it sometimes works against my afc settings and I have to reset the PCM to get the cell back to zero. I think someone could rewrite the code to have cell 3 to learn at some unobtainable value (like > 800 gps) that way the LTFT would always be zero and not screw up my afc by removing fuel.


Uhhh...back to your problem, I dunno, if that is with a stock cam then that's a strange condition.

Mike