friend's KR happy 99 camaro

[BobDoLe]

I have attached a scan log and tune file for a friend's 99 v6 camaro.
All we have done to his car is adjust the speedometer for 3.42 gears, removed speed limiter and made shift times just a little quicker.

While running his car to calibrate the speedometer against my handheld GPS (tiresize / gear usually results with speedometer off by 1-3 mph probably because of tread depth on older tires), I noticed that he was getting KR all over the place. His tune was stock before I plugged in and the only code that came up was an immature BCM restraint.

Could this be normal for a 99 camaro? his modifications: 80 series flowmaster muffler and ram air intake with whisper lid. my 01 camaro had maybe 1-2 degrees KR (max) when I scanned it on a stock tune - at that time I just had a whisper lid.

He says he let the car sit for 2 weeks while he was out of town. During that time, it was driven maybe 2 days for 50 miles. I was thinking that the stale gas could have caused the KR.

Any thoughts?

[slow6]

It reallly seems the reason for the KR is because he is running slightly lean. I saw his LTFT fuel trims....mostly all lean
Seems he should do VE SD tuning.

Might wanna reduce timing a little (or something)in that wot area, as you are having KR

Bad gas? yes, its possible.
bad gas = less fuel = leaner AFR = more KR

Yes Dans right, cold weather = makes you lean

edited cause I didnt look at the whole scan, sry

[usd2sing]

throw some 93oct or race fuel in it (option but not really necessary)
looks like a little maf cal is in order.

trims locking in at wot look decent.

little FYI, the extremely cold weather is playin hell with alot of peoples tunes.

try a little part throttle and cruz maf cal should help you out.

[EC_Tune]

I don't think 2-week old gas will go foul unless there are other problems with that tank of gas to begin with.

Not unusual to see a stock car with KR and Lean. There's a lot of tolerances that stack up in the final parts list for a motor and GM has to account for them somehow.

This motor may have a bit more compression than normal or may have some octane creep from chamber deposits. Again many things can change calibration requirements.

[MMGT1]

Just a guess. Check the condition of the trans mount, well, ALL MOUNTS come to think of it. Maybe a bad one in there? Looks like KR is happening on the shifts? Car hits over 40* timing without KR and then has KR @ 2000rpm....that's what is making me think is is not in the tune, again, just guessing

[BobDoLe]

we're going to scan it again now that the weather is stabilizing. then we'll adjust the spark some and check for knock.

thanks for the input!!