P0171 lean
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1st Gear
Joined: Jun 2024
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P0171 lean
Hello all. I'm new to the forum, so what's up.
my sons 05 f150 stx 4.2 is running a lean code on bank 1 and engine shutters and runs like crap. What I've done, injector on bank 1,plugs, wires, ignition coil,maf, egr valve, fuel pump, fuel regulator, fuel filter,. Did a smoke test, sprayed starter fluid and tried water, both while watching rpms. No cracks in plenum. Checked compression on cylinder 1, compression good. Also the long term fuel trim is super high 29.7 and all the others are highish also 02 sensor seems good, Checked it on scanner and its acting just as 02 sensor2 upstream, all voltage is similar. I'm lost and have zero clues at this point. Thanks.
my sons 05 f150 stx 4.2 is running a lean code on bank 1 and engine shutters and runs like crap. What I've done, injector on bank 1,plugs, wires, ignition coil,maf, egr valve, fuel pump, fuel regulator, fuel filter,. Did a smoke test, sprayed starter fluid and tried water, both while watching rpms. No cracks in plenum. Checked compression on cylinder 1, compression good. Also the long term fuel trim is super high 29.7 and all the others are highish also 02 sensor seems good, Checked it on scanner and its acting just as 02 sensor2 upstream, all voltage is similar. I'm lost and have zero clues at this point. Thanks.
Last edited by Jesus=king; Jun 5, 2024 at 07:44 PM.
Hotshot
Joined: Jul 2005
Posts: 11,931
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all the little 1/4 inch vacuum hoses are 20 years old.. If one is cracked it can suck air... Pull them off one at a time and check for flexibility.. I had two by the exhaust manifold that got HARD and CRACKED on a 5.4 at a bout 15 years old.
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