Red150stx

Hey guys I recently bought my 05 Stx and now I'm getting the dreaded lean codes I replaced the maf and still ltft are at 29 and stft are at 21 at idle can't figure it out could the PCv valve be bad?

lewissa81

Have you checked for vacuum leaks

Red150stx

Yes no leaks that I can find

lewissa81

How old is the fuel filter? What kind of condition is the FPDM in?

Red150stx

Fuel filter is rusty as all hell

lewissa81

Change it. Put a motorcraft one in. If it's real old, it could be clogged and not allowing enough fuel pressure for the injectors to function properly. Even if it's not causing the lean condition, it's sure not helping. They should be replaced fairly regularly.

Red150stx

Thanks will do 👍

Red150stx

Does a slightly clogged filter make these codes cause my truck runs and drives awesome but when I first start it up in the morning I get a gas smell

screw05

I had only the p0171 code. My mechanic said the only thing he could find was a leak in the passenger exhaust gasket. He replaced it and cleared the code about 500-700 miles ago and hasn't came back on yet. Good luck. I heard this can be many different things.

Red150stx

Thanks from what I've been reading it's either the fuel filter or pump now