Engine code p0171 and p0174
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Engine code p0171 and p0174
I have a 01 f150 with v6 4.2l 125000 miles on it. just bought the thing. it had 9 engine codes on it ranging from egr to o2 sensor, missfire and etc. They had a exhaust on it with no cats or o2 sensors. So for I am down to two codes. I fixed every thing else except the p0171 and p0174. I replace egr and sensor check for vacum leaks line by line with a vacum pump. replace cam sensor, o2 sensor down stream, fuel filter new exhaust (oem) and clean mass air flow also replace pcv valve. replace dpfe sensor also. I removed the upper intake manifold and clean out a lot of junk in there also. egr ports and all with carb spray. I didn't replace the rubber isolators or replace the gaskets in the intake manifold though. they seems fine. What can the problem be. can some help me please. 
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Joined: Aug 2004
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From: Greenvile, SC
I have a 01 f150 with v6 4.2l 125000 miles on it. just bought the thing. it had 9 engine codes on it ranging from egr to o2 sensor, missfire and etc. They had a exhaust on it with no cats or o2 sensors. So for I am down to two codes. I fixed every thing else except the p0171 and p0174. I replace egr and sensor check for vacum leaks line by line with a vacum pump. replace cam sensor, o2 sensor down stream, fuel filter new exhaust (oem) and clean mass air flow also replace pcv valve. replace dpfe sensor also. I removed the upper intake manifold and clean out a lot of junk in there also. egr ports and all with carb spray. I didn't replace the rubber isolators or replace the gaskets in the intake manifold though. they seems fine. What can the problem be. can some help me please.
Welcome to FTE!
Also for posterity.. the 171 and 174 are banks 1 & 2; "System Too Lean"
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Joined: Oct 2010
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Yes it is common for these bolts to be bad
I replaced mine after doing everything else that you have. They will look fine but they're not. Changed them and now no more codes and truck passed inspection 4.2liter with 150,000 miles. The funny thing is your truck will seem to run ok with this problem
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