Lean code problems 01 f150 5.4 146000 mi
Lean code problems 01 f150 5.4 146000 mi
Hey all, I have been trying to diagnose this problem for quite some time now. I am getting the P0171 and P0174 codes all the time. At first I assumed it was the Mass air flow sensor so I changed It. Still the same problems exist. I have checked the fuel Pressure and I am getting about 31 psi so I think thats about right. I have checked all of the pcv lines for and holes in the elbows and I have found nothing wrong. I changed the pcv valve too since it was not ver expensive. I have sprayed starter fluid all on top of the motor trying to find a vaccuum leak and found nothing. I checked the egr valve with vaccuum and It moves on its own but Im not sure if its leaking. The only two things I can think of that it could be at this point would be either a vacuum leak on the lower intake manifold gasket or the egr valve is not fully closing but if the latter was the case, shouldnt I get a egr code? Any Ideas would be greatly appreciated at this point.
Senior Member
Joined: Jul 2007
Posts: 3,291
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From: Beaverton Or.
Do you have any exhaust leaks? With those miles, I would pull the throttle body and elbow to clean things up and replace all the gaskets including the egr. There are write ups around here with step by steps on how to do that. It will help in many ways and could point to a vacuum leak your not seeing.
yeah i cleaned everything down to the upper intake, it all cleaned up really well. as far as exhaust leaks, i dont believe i does because it has true dual exhuast on it. the pcv lines are all clean and clear, i cleaned the iac and soaked it but that didnt help anything either. im thinking if it does have a leak it will be where i cant reach it on the underside of the lower intake manifold gasket.
