So I'm new to forums. But I'm having problems with my car. It's been in and out of shops for two months now. I keep get codes P0171 & P0174, saying it's running lean in bank 1 & bank 2. No one can figure anything out and I don't know what else to do.

 

Welcome to the site. Have you done (or had someone else do) any mods to your car? CAI? Anything? Or is she 100% stock?

 

fuel pressure regulator?? mass air flow sensor, but I would think that has been checked into.

 

Right - he didn't say what has been checked. Was anything done to the engine just prior to the codes or did they just show up one day driving?

I didn't look up the codes but assuming they are correct - both banks showing lean, then it is weakened fuel flow (or sensor related). How's that fuel filter? Fuel pump failing prematurely? Did they check voltage?

Or something pre-intake manifold (common to both banks) allowing too much air. (So probably isn't O2 sensor going bad or unhooked). MAF needs cleaning, leaking air inlet, new CAI w/o tune?

 

hOW MANY MILES ARE ON IT?

 

Yes I have mods. CAI, Magnaflow exhaust (no cats), bbk 62mm throttle body, and bama performance tunes. Had a shop run smoke through intake, fixed a couple vacuum leaks, fuel pressure was ok. Still nothing fixed

 

Also, I myself replaced downstream O2 sensors, fuel filter, plugs, and tps sensor, before taking it to shops to get looked at.

 

CAI and a tune, notorious for causing the car to throw a lean code. My guess is the 62 mm throttle body could be a contributing factor as well.

 

Sounds like time for a dyno tune.

 

cdynaco is right greenmachine. Let a shop put it on a dyno and adjust your fuel / air parameters while the car is running. You'll get the optimum tune and they can make sure it stays in a safe range across the RPM range.

 

I've been wanting to get it dyno tuned. But was gonna wait till I had out gears, cams, and headers on it so I could have everything done and wouldn't have to keep going back. Shop it's at keeps talking to a ford tech line and they think it is something with the throttle body. I'm thinking the actuator on it might be bad seeing how it's from the stock throttle body