Running poorly
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Joined: Aug 2000
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Running poorly
Hey group,
My `91 Explorer with the 4.0L engine starting running very poorly all of a sudden. It comes and goes while you are driving and when it is running poorly it will stall at idle. At speed it bogs down and feels like the brakes have been put on. Revving up the motor in neutral causes it to put out some black smoke. My guess is a bad O2 sensor. Any other thoughts?
Mark
My `91 Explorer with the 4.0L engine starting running very poorly all of a sudden. It comes and goes while you are driving and when it is running poorly it will stall at idle. At speed it bogs down and feels like the brakes have been put on. Revving up the motor in neutral causes it to put out some black smoke. My guess is a bad O2 sensor. Any other thoughts?
Mark
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Joined: Apr 2000
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From: PNW
Running poorly
Since it sounds like it's running rich, the O2 sensor is a good thing to check. But I would also check the fuel pressure. You could have a bad fuel pressure regulator. And if you haven't been good with basic maintenance (plugs, wires, etc.), get caught up on that first before you try troubleshooting.
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Running poorly
Well I finally got the time to check the FPR and it reads 35 to 39 psi, which is right on spec. Also, the pressure increased when I pulled the vacuum line so it appears to be working just find. I put in a set of plugs and ignition wires too since I was not sure how long it had been since they had been replaced. Lastly, I disconnected the O2 sensor and that did not seem to have any impact on the running either.
So it is still running real rich and missing, stumbling, and stalling. Any suggestions as to my next course of action? Any help is greatly appreciated.
Mark Child
So it is still running real rich and missing, stumbling, and stalling. Any suggestions as to my next course of action? Any help is greatly appreciated.
Mark Child
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Joined: May 2000
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Running poorly
Could be MAF sensor seen plenty of them go bad would cause engine to load up and puff black smoke . Did you do an EEC test there should be a code. If no codes definitely check fuel psi . Possible regulator bad psi to high.
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Running poorly
Thanks for your comments and thought about the MAF. I have already checked the FPR and it read 35 to 39 psi. That seemed to be the logical problem but it is reading right on spec. I don't have a code scan tool. Does the method of tuuring the key on and off work so that you can easliy undersatnd what you are being told?
Thanks
Thanks
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Running poorly
Just a thought, after everything else fails, check the catalytic converter. When these things clog, vehicle loses power and won't idle. Don
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Posting Guru
Joined: Aug 2000
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Running poorly
>Just a thought, after everything else
>fails, check the catalytic converter.
>When these things clog, vehicle
>loses power and won't idle.
>Don
"Nothing lasts forever except natural stone and old Ford trucks." (Willie Nelson)
>fails, check the catalytic converter.
>When these things clog, vehicle
>loses power and won't idle.
>Don
"Nothing lasts forever except natural stone and old Ford trucks." (Willie Nelson)
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Joined: Jun 2000
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From: CANADA
Running poorly
Did you clean the MAF or replace it? I am asking because I have heard about cleaning it and am not sure what kind of cleaner to use on it. I don't want to spray it with anything and destroy it by using the wrong cleaner.
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Running poorly
Hoppy,
I tested the output signal by back probing the connection and found the output to be almost fixed at all RPMs at about 2.6 volts. As you may know, the output is supposed to be about 0.5 to 0.7 volts at idle and increasing as engine speed goes up. The output of 2.6 was telling the engine management system that the engine was running at a significant RPM (when in fact it was only idling) and thus it was being provided a bunch of gas.
I don’t think cleaning it would have helped. It would appear to me as thou there was a real problem with the unit’s ability to maintain the screen temp and probably an open circuit someplace. Additionally, the old unit did not look visibly dirty.
I paid $120 at the local auto parts store for a remanufactured unit.
I tested the output signal by back probing the connection and found the output to be almost fixed at all RPMs at about 2.6 volts. As you may know, the output is supposed to be about 0.5 to 0.7 volts at idle and increasing as engine speed goes up. The output of 2.6 was telling the engine management system that the engine was running at a significant RPM (when in fact it was only idling) and thus it was being provided a bunch of gas.
I don’t think cleaning it would have helped. It would appear to me as thou there was a real problem with the unit’s ability to maintain the screen temp and probably an open circuit someplace. Additionally, the old unit did not look visibly dirty.
I paid $120 at the local auto parts store for a remanufactured unit.
