Formulaone02

02 firebird formula, LS1.... No problems until I added a K&N cold air aftermarket MAF housing, a superchips cortex tune, SLP exhaust, and bypassed the TB coolant..... Now I'm getting lean codes on both banks... Any help would be much appreciated, I've cleaned the MAF sensor from extra oil from the filter and checked for vacuum leaks none found /:

Darkman

iTrader: (2)

Is the tune reversalible?

Formulaone02

Yes and I've tried that, code came back

Darkman

iTrader: (2)

Have you tried reversing what you did on the MAF?

Formulaone02

I just replaced the housing and the stock is long gone

Darkman

iTrader: (2)

Okay. I don't see anything on the list of things you changed that would trigger lean codes other than the tune and something wrong with MAF setup. If you think those have been eliminated, that leaves the traditonal causes of lean codes - check the fuel level, the fuel pressure, and/or change the fuel filter.

cruisin'73

iTrader: (8)

Darkman, thank you for posting that awesome diagnostic procedure, where did you find it? I have been intermittently getting those code in my Yukon. So when I was scrolling through recent posts and saw this one I thought I would check it out, and I am glad that I did. Thanks!

Formulaone02

Fuel level is good, I change the fuel filter every other oil change the only thing I'll have to check is fuel pressure, I've even done a fuel treatment and I'm still getting the codes

Darkman

iTrader: (2)

Post the code numbers.

Formulaone02

P0171 and P0174