This question (problem) may have already been answered.... sorry if it has. But my car needs to reinspected B/c it failed emissions, im throwing three lean codes. The codes are P0171, P0174, P1416, the SES lights on but it drives normal. i know they're lean codes but how can i fix this, what could have caused me to throw these codes? Thanks for any help or input. oh yea.....please help!!

 

Sounds like you have to get your LTFTs close to zero or slightly negative. You could rescale the IFR (injector fuel rate) table.

BTW, have you recently modded without tuning, like headers or intake? If not, you'd have to rule out mechanical problems like air leaks, or anything that might alter your A/F ratio.

 

No real mods besides a few bolt-ons. Intake mods - whisper lid with K&N filter, smooth bellow, Granatelli MAF, Fast Toys ram air kit. The odd thing is my car passed emissions last fall, and i havent done any performance mods since then?! well the only one i did this winter was just a March underdrive crank pulley, that wouldnt effect this? or would it?

 

I don't think the underdrive pulley would cause you to go lean.

Since you haven't done any mods, and the codes appeared, I would check to make sure everything is buttoned up, like exhaust, headers, intake, where the throttle body connects to the intake.

Maybe your car was borderline lean but not lean enough to throw codes, but something changed that put you over the threshold. Go through the car and make sure everything is tight, especially the intake and everything connected to it. Even if that puts you back to where you were (no codes), I would definitely scan the LTFTs and bring them as close to zero as possible. Your LTFTs would have to be over +25 to throw those lean codes.