[Jman]

I've been getting leans codes off and on for the past 9 months. I changed the O2 sensors about 8 months ago, the fuel filter and pump 9 months ago, and more recently the MAF sensor, PCV valve and hoses, the thermostat and coolant temperature sensor, and the EGR Valve. Everything except the MAF sensor and EGR valve I knew had to be replaced.

After clearing the codes each time, they come back on within a week, generally with high fuel trim ratios. Again today, just a couple days after replacing my EGR valve, the check engine light came on. But this time the fuel trim ratios seem fine (STFT 1 is -3.1, LTFT 1 is 5.5., STFT 2 is -1.6, and LTFT 2 is 7.0). I'm at a loss as to what to do next.

I have a 2001 Ford Explorer XLS with a 4L, V6 engine.

 

[WhatsUpDOHC]

I've been getting leans codes off and on for the past 9 months. I changed the O2 sensors about 8 months ago, the fuel filter and pump 9 months ago, and more recently the MAF sensor, PCV valve and hoses, the thermostat and coolant temperature sensor, and the EGR Valve. Everything except the MAF sensor and EGR valve I knew had to be replaced.

After clearing the codes each time, they come back on within a week, generally with high fuel trim ratios. Again today, just a couple days after replacing my EGR valve, the check engine light came on. But this time the fuel trim ratios seem fine (STFT 1 is -3.1, LTFT 1 is 5.5., STFT 2 is -1.6, and LTFT 2 is 7.0). I'm at a loss as to what to do next.

I have a 2001 Ford Explorer XLS with a 4L, V6 engine.

Do you have a plastic intake? Maybe a crack in the intake.

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[Jman]

Do you have a plastic intake? Maybe a crack in the intake.

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I've checked that but probably should take a closer look since I've replaced all of the hoses that had cracks.

 

[DAVID L]

P0171,P0172 LEAN BANK 1or 2. The silicone gaskets at the base of the intake to head lose elasticity an sealing.
Google the codes and look at Youtube. It is a simple job but a pain in the A-- to get to.

 

[JAREDM]

hey Jman, let us know what develops. i've been dealing w same issue in my '00 XLT for months. haven't done much about it because yeah, was informed it could be so many various different things. ...i'm not getting used to that check engine light :-/

 

[DAVID L]

hey Jman, let us know what develops. i've been dealing w same issue in my '00 XLT for months. haven't done much about it because yeah, was informed it could be so many various different things. ...i'm not getting used to that check engine light :-/

I replaced the lower intake and gaskets 4 years ago. Runs fine now. Replace the PVC hose under the intake while you have access to the valley. Vids on Utube. David