p0171 Lean on Bank one
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Registered User
Joined: Oct 2003
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From: Charleston, SC
p0171 Lean on Bank one
4.6 Expedition. Having the same prob. Ruff at idle fairly smooth after it warms up. Did notice the instrument cluster dials tach, fuel... ping all the way to max then back to zero and then settle at normal. Seems like a power loss at start up?? Added fuel injector cleaner, replaced the fuel filter, removed the K&N air filter replaced with paper filter, replace both Fwd O2 sensors. Work fine for about a week, cleared the code & then it returned. Have read alot of tips on this subject. Will use my F-150 5.4 parts for trouble shooting purposes if required.
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Joined: Jan 2002
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olliera,
Do a search on the code or the word "lean". You'll come up with much info.
Lean means too much air compared to fuel. The first thing to do is clean the MAF sensor. If it is dirty it will let more air through than the ECM will "see".
Next look for vacuum leaks...bhah, blah, blah.
Do the search you'll see.
Good Luck,
Bill
Do a search on the code or the word "lean". You'll come up with much info.
Lean means too much air compared to fuel. The first thing to do is clean the MAF sensor. If it is dirty it will let more air through than the ECM will "see".
Next look for vacuum leaks...bhah, blah, blah.
Do the search you'll see.
Good Luck,
Bill
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Registered User
Joined: Oct 2003
Posts: 9
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From: Charleston, SC
Lean on bank one
THANK FOR THE INFO. Did a voltage ck on the MAP sensor & cleaned it Seems to work OK till the temp dropped yesterday, still won't idle @ 1200 RPM, IT'S Idling @ 800 when cold. This one also is driving me nuts, TURN THE IGNITION TO ON W/Out STARTING, THE WHOLE INSTRUMENT CLLUSTER/DIALS PING TO THE RIGHT/HIGH SIDE THEN SETTLE BACK TO NORMAL. Some sort of pwr. fluctuation??
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Joined: May 2001
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From: Maryland
it sounds like you have a resistance problem or a poor connection at the battery or a faulty ground somewhere.
when the needles ping all the way up like that it is a sign that the pcm was reset. this could also be your idling problem the pcm never learns the proper idle because it is always being reset.
the lean on one side is almost always one of two things. first off you can basically rule out any sensor that affects the entire engine function. IE: MAF, Air temp, coolant temp, egr, dpfe, etc.
the mostlikely culprit is an 02 sensor (jsut because they are new doesn't mean they are good) the second is the 02 sensors wire. trace it back to its conector and clean it out really well.
oh and the truck should idle at 600-800 rpm regardless of outside temp. (once engine is at full operating temp of course)
when the needles ping all the way up like that it is a sign that the pcm was reset. this could also be your idling problem the pcm never learns the proper idle because it is always being reset.
the lean on one side is almost always one of two things. first off you can basically rule out any sensor that affects the entire engine function. IE: MAF, Air temp, coolant temp, egr, dpfe, etc.
the mostlikely culprit is an 02 sensor (jsut because they are new doesn't mean they are good) the second is the 02 sensors wire. trace it back to its conector and clean it out really well.
oh and the truck should idle at 600-800 rpm regardless of outside temp. (once engine is at full operating temp of course)
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Joined: May 2004
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From: Georgia on my mind...
Follow the PCV tube to the back of the throttle body, check for leaks.
The guage sweep is normal, the instrument cluster proves itself out whenever the key is turned on.
The guage sweep is normal, the instrument cluster proves itself out whenever the key is turned on.