Running lean
Thread Starter
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Member
Joined: Oct 2002
Posts: 12
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From: Ohio
Running lean
'97 f150 sc 4x4 w/ ORP 183,500+ miles 4.6l
running lean on both banks.
what could be the culprit?
changed the fuel filter and cleaned the MAF
when coming to a stop the rpm's drop low... and on two occasions has caused the engine to stall.
What should I look at next? oxygen sensors? fuel pump?
running lean on both banks.
what could be the culprit?
changed the fuel filter and cleaned the MAF
when coming to a stop the rpm's drop low... and on two occasions has caused the engine to stall.
What should I look at next? oxygen sensors? fuel pump?
Senior Member
Joined: Feb 2004
Posts: 659
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From: Wisconsin
You more than likely have a EGR LEak. Check the passenger side engine and rear of intake vacuum tubing for cracks, and melts, and holes. Listen too! You'll probably hear a sucking sound... That'll point it out.
or pull the valve and put your thumb over it.. you should feel a STRONG(at least vacuum cleaner strong or better) suction, if its weak or mild, you found your problem.
or pull the valve and put your thumb over it.. you should feel a STRONG(at least vacuum cleaner strong or better) suction, if its weak or mild, you found your problem.
Senior Member
Joined: Feb 2004
Posts: 10,390
Likes: 10
Hi.
Your o2's ( the front pair) are way overdue for changing., if you haven't already.
When was the last time your injectors were professionally cleaned?
Yes, check the fuel pressure. I think 35 psi is around the correct range ?
EGR system been cleaned?
DPFE checked/changed?
Post the actual codes for the experts ( not me) here to help further.
Do a Search on this condition here - been discussed many times...
Cheers & good luck.
Homo Habilis
Your o2's ( the front pair) are way overdue for changing., if you haven't already.
When was the last time your injectors were professionally cleaned?
Yes, check the fuel pressure. I think 35 psi is around the correct range ?
EGR system been cleaned?
DPFE checked/changed?
Post the actual codes for the experts ( not me) here to help further.
Do a Search on this condition here - been discussed many times...
Cheers & good luck.
Homo Habilis
Thread Starter
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Member
Joined: Oct 2002
Posts: 12
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From: Ohio
...
I will check in to the possible vacumm leak.
The engines doesn't surge unless you come to a stop and then it will ussually drop down then back up to normal.
mpg hasn't really been hurting either. been getting around 17.5 mpg the last few times I checked. (drive 35m. one way to work)
Nothing has been professionally cleaned
thanks for all the advice
The engines doesn't surge unless you come to a stop and then it will ussually drop down then back up to normal.
mpg hasn't really been hurting either. been getting around 17.5 mpg the last few times I checked. (drive 35m. one way to work)
Nothing has been professionally cleaned
thanks for all the advice
Senior Member
Joined: Sep 2005
Posts: 2,618
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From: Atlanta, GA
You have the same problem I have right now. But I just added a blower. You are more than likely running rich, but as stated, it could be a vacuum leak as well.
You can check for pending codes and old codes with a scanner as well as current codes.
You can check for pending codes and old codes with a scanner as well as current codes.
Senior Member
Joined: Oct 2002
Posts: 7,295
Likes: 125
From: St. Louis (Out in the woods)
Lean readings on both banks are neither O2 sensors or EGR problems.
You have a vacuum leak.
Most common location is the rubber elbow on the PCV hose. Extremely common failure. SEARCH keyword "PCV leak" or "P0171 P0174" for many threads with details.
Vacuum leak is also causing your surging and stalling, especially when coming to a stop. The IAC is unable to properly meter air past the closed throttle plate so it overshoots and looses control of the idle air management.
Steve
You have a vacuum leak.
Most common location is the rubber elbow on the PCV hose. Extremely common failure. SEARCH keyword "PCV leak" or "P0171 P0174" for many threads with details.
Vacuum leak is also causing your surging and stalling, especially when coming to a stop. The IAC is unable to properly meter air past the closed throttle plate so it overshoots and looses control of the idle air management.
Steve