scanned 97ss lt1, 6sp ,slp shorties, k&n,


i reset the computer to start fresh because my long term fuel trim was maxed @25 at idle....so i watched as my short term went lean and then my long term slowly worked its way to +25% lean....now the weird part is in every other block, seriously everywhere in all conditions ,were within -3 to +3 in both short and long term fuel trims ...the only thing else i noticed is under (no throttle deceleration) long terms were up to +14% ..... after 40 miles it is still the same...fuel press is perfect and all header bolts are tightened up. i even listened for vacuum leaks with a mechanics stethoscope ,o2 are new and working..all is well...............What would cause me to be lean at idle?

thanks a bunch guys..

 

Car is supposed to be somewhat lean at idle i believe, my car was tuned for my cam by Madz28 who knows his ****. On the dyno my car had like a 17/1 air fuel ratio which is way lean, so i think its supposed to be that way.

 

"Stock" tune keeps the car at 14.7:1 at idle. That's the purpose of the long term fuel corrections. If the engine is running correctly, no vacuum leaks, no misfires, no exhaust leaks, etc.... the long term corrections should be no greater than +/-5%. If he's getting +25%, something is causing it to run too lean, or its a "false" lean.

Are you getting +25% on both banks, or just on one? Knowing that would help point to the source of the problem.

The no throttle/decel (Cell 17) long term, as well as the Cell 18 values are calculated from the other cells, using some sort of algorithm. Correct idle (Cell 16) and you will correct no throttle/decel.

 

yes Injuneer it hits the same 25% on both banks ... the car pulls hard and idle is perfect so i ruled out injectors and maf (i get the same results switching from two different mafs) What would be other causes??

thanks a million i need to smog this car like now and all the help is greatly appreciated.....

 

A minor vacuum leak would do it, and disappear at anything above idle. You need to go over every hose and connector on the intake... these cars are getting so old the hoses are starting to crack.

 

What are the IAC counts at idle?

 

THATS IT!!!!!!

i found it.. my pcv rubber elbow had a pinhole. heck i couldn't even hear it with a stethescope.. as soon as i fixed it i started the car and my short term went from +6 to - 38 / long terms were still +25 and the car started sputtering so i shut it off and reset the computer.......on start up the car now is back with long terms/ short terms at or very near "0" .... i noticed that now the car is more on the -% side(rich)but now after a long drive, on idle the long terms are -11.2 .. is the computer still re-adjusting?

 

THATS IT!!!!!!

i found it.. my pcv rubber elbow had a pinhole. heck i couldn't even hear it with a stethescope.. as soon as i fixed it i started the car and my short term went from +6 to - 38 / long terms were still +25 and the car started sputtering so i shut it off and reset the computer.......on start up the car now is back with long terms/ short terms at or very near "0" .... i noticed that now the car is more on the -% side(rich)but now after a long drive, on idle the long terms are -11.2(both banks) .. is the computer still re-adjusting?