P0171 cel

[ericsbestshot]

well i got this CEL code the day after i got my car up and running after a timing belt change. The only differance with the car that i can tell is that the RPMs drop when idling (never happened before and may be linked to the timing belt install). Autozone said it was for my #1 is running to lean or the o2 sensor is bad. I used some fuel injector cleaner and has not helped yet. Anyone ever had to deal with this Code before?

[ben91]

system too lean, bank 1.

has nothing specific to do with cyl 1. the "1" means bank 1. since this is a 4 cyl motor with only a single primary o2 sensor, bank 1 is the only bank.

busted o2 sensor should result in system too rich. problem is most likely a maf problem, possibly pcv valve or vac leak (though vac leak should idle up)

[Doppelgänger]

Well, when I was taking a look at Matt's car, it had a large vacuum leak and it idled low.

Double check all the couplers between the filter and the throttle body...spray some carb cleaner around them to see if the idle changes. Same with any other suspect vacuum lines. It's a start.

[matredd]

I'm getting this code right now actually. I think it's because of an exhaust leak before the first o2 sensor. I managed to break one of the studs that the egr pipe attaches to on the intake manifold. It's only being held on by one nut. Now I need to figure out if I can get the stud out without taking off the intake manifold (which i've never done before).

[MoD_Scotty]

I just had this code, and fixed it. Same dipping idle issue, too. It was a vacuum leak. I found the leak by (with the engine running), spraying some brake cleaner, one spot at a time, around the intake mani. Turns out I had destroyed an injector insulator the last time I messed with the injectors. You'll find the leak when the engine revs up immediately after you spray the trouble spot.

I bet you forgot a vacuum line somewhere in the whole timing belt process.

[Reverend Greg]

i WOULD VENTURE THAT IT IS THE SENSOR IN YOUR AIR INTAKE THYE ONE WITH THE SCRAP OF HOSE HOLDING IT IN

[RotorNutFD3S]

Holy caps lock batman! :lol:

[Reverend Greg]

Yeah sorry about that,The wife locks it

[matredd]

Yeah i think you can clean the inside of it with some electronics cleaner

[Reverend Greg]

Acquire a new piece of material for a grommet to re seal that thing I think it is the IAT sensor

[MoD_Scotty]

I kinda doubt it's before the throttle body, but I guess it's possible.

[Doppelgänger]

Unmetered air is unmetered air if there is a leak after the MAS. Since the IAC is still letting some air through, if there is a leak, the MAS and the O2 will be showing different results to the ECU which will throw a CEL.

[simontibbett]

ALL THESE PEOPLE ARE WRONG.

Your intake manifold is falling off, and will cause the floor board to fall out. Turn NOS off under the seat cushion.

[MoD_Scotty]

Unmetered air is unmetered air if there is a leak after the MAS. Since the IAC is still letting some air through, if there is a leak, the MAS and the O2 will be showing different results to the ECU which will throw a CEL.

I agree, and I totally grasp that concept. Me and MAFs are tight.

One of the hoses could have torn while pulling them off the car...it may not be obvious unless you inspect them closely.

[ericsbestshot]

ok i'll check the small gromet thing but i think that its on good and not letting in air.
No leaks around the Intake manifold. Did the brake cleaner thing on all the hoses leading to and from the manifold.
Could it just be that the o2 sensor is bad?