"Running Lean"

[white3800firebird]

OK, I've been trying to figure out why the car still has lean codes even though the check engine light is on. Haven't checked it recently but when the light was on LTFT read about 15%. Again light is not on but the smog techs monitor scanner still picks up P0171 and 0174...the other thing is that after 3 months the monitors for the EGR and Cat wont go off. The car has already been to my friends at the dealer to check for leaks or anything that would cause the lean condition. They found a little bit of water but nothing to be concerned about, the EGR is new along with the fuel sending unit. The engine has the following mods: Whisper lid, SLP intake, P&P intakes, milled heads, Taylor 10.4mm wires, MSD coils, Iridium plugs and headers. Non of these mods are recent enough to suggest one of the parts caused it. The car runs on 91 Chevron. What am I missing?

[2.8 Bird]

Re: "Running Lean"

Have you changed your fuel filter and got your injectors service? I would probably look into those.

Also, you can spray clean your MAF that might help too.

[thebeewantsboost]

Re: "Running Lean"

not sure what the computer actually uses to report a lean condition... it seems obvious that it would be oxygen sensors... however.... 15% ltft's isn't that far out of wack.... i know its capable of compensating atleast a little higher than that. i mean the oxygen sensors are doing their thing and the motor is compensating for probably ethanol in your gas. i know i'm not much help, just brainstorming with ya

[dmw319]

Re: "Running Lean"

i would look at your 02 sensors

[ssms5411]

Re: "Running Lean"

i would look at your 02 sensors

X2 on checking the O2's.

[bigbrian442]

Re: "Running Lean"

15% rich or lean is what sets those codes. Try cleaning the MAF and resetting all codes and fuel trims. If that doesn't help try tuning the MAF.