We bought the car 2 weeks ago and the other day the SES light came one. Originally I just assumed the last time I got gas the cap wasnt put back on tightly but when I pulled the codes it came up with Fuel Trim System Lean Bank 1 & 2. Anyone seen this before and have any idea what could be causing these codes. Other then exhaust work and a gutted air box w/ K&n filter theres nothing else done to the car that I can see but of course I havent had alot of time to really investigate the car.
Thanks

 

my guess would be the K&N got too much oil on the maf sensor.

Ryan

 

I stay away from K&N filters because of the oil and how it affects the MAF; especially on a "side feeder" vehicle where the MAF is very close to the filter itself. Clean it to make sure. A couple of years ago, GM also issued a notice about the same exact problem.

In your case I would say it's the gutted air box allowing more air in and it needs to be tuned. I removed the air silencer in the air box on my TB SS and the fuel trims went very lean (+12-20%), so I added fuel and now they're back to normal. Is the MAF screen still in place?

 

Yea the MAF is still in place, I'll clean the MAF and see what happens, Ive seen it before when the filter is over oiled that it messes with a MAF. Is rubbing alcohol safe for these maf sensors? I just want to pinpoint the problem so I can correct it now so I do not run into a major problem on the road one day.