Lean issues.....

[stonemonk9]

My friend has a 00 z28 that is for the most part stock besides a lid, headers, and a turbo400. He just bought the car w/ a diablo tune on it and it ran ok. He decided to uninstall the diablo to sell it and as soon as he did that the car ran terrible w/ a lean miss. The fuel trims were WAAAY off, like 50%. I went ahead and tuned it in sd mode and then dialed the maf in and now it runs good untill the upper rpms where it still goes close to 50% lean. The thing I noticed is that when he does more than 3x% TPS it seems that his o2 sensors read extremely lean, like in the 0-100mv range....

here is the current tune and a log, at the end of the log you can really see it...

[stonemonk9]

no suggestions?

[roberttimmons]

no wideband? Does the car have stock inectors? You need to put it back into open loop turn the maf back off and recheck the entire VE. If the problem goes away with the maf off then you know its an issue with the maf scaling.

[stonemonk9]

no wideband, and yes stock injectors, we have yet to hook the wideband up, in sd mode it runs much better, and ill try that, however i still wonder if it can be something mechanical or something else...?

[Cantalope Kid]

Pm'ed you...interested in your solution for future reference. - So what were your findings?

[stonemonk9]

no luck yet, havent had time to look at his car recently..... ill update ya when i find something

[stonemonk9]

well, i know this was over a year ago, but just incase someone ran into a similar issue, it ended up being a dirty maf, we cleaned it and everything ran good