Im getting the codes P0171, P0174. Ive had a computer scanned my truck and the oxygen sensors are fine, no sensor seemed to be faulting. Ive looked at the vacuum lines and none seem to be frayed or open. Any other suggestions what to look for or anything else to try. Thanks for any input. Also had the plugs, coils, injectors replaced a year ago.

 

Fuel filter?

 

Forgot to add that. Changed that 4 days ago.

 

I'd change o2's just for peace of mind

 

Those things just aren't cheap though. I wouldn't mind it if i knew for a fact it was that. Just don't have the money to just try things that expensive.

 

The o2's are doing their job, I would suspicion a vacuum leak somewhere. Possibly the PCV elbow on the back of the intake, since both banks are lean. Other possibility of course is the fuel pump is actually getting weak. What is the fuel pressure?

 

I replaced the PCV about a year ago when i did my tune up. I looked back there but i will check again. No clue on the fuel pressure. My mechanic tested my truck using one of those Snap On computers. Would that show fuel pressure?

 

Any leak in the intake tract down stream of the mass air flow sensor will cause a lean condition. First thing I would check is your intake couplers.

 

Well i cleaned the Mass Air Flow a few days ago. Since then not a single trouble code. Fingers crossed it was that being dirty.

 

Code started back up. Cleaning the mass air flow seemed to help a tiny bit. Could a EGR valve cause a lean code?