Misfire at idle, no check engine light
11-24-2013, 06:04 PM
#1
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Misfire at idle, no check engine light
I drive a 94 cherokee with the 4.0 and it started misfiring at low RPMs the other day. I've read a lot of different threads on this issue but have not found anyone who actually had success with this and i don't want to waste money playing guessing games. I'm not sure if this could have anything to do with the problem, but I replaced the valve cover gasket the other day to get rid of a leak, and the leak is now gone but the following day when I started it up it was idling really rough, but once I begin driving it feels fine. Its been doing this for three days now with no check engine light on. This morning though, the CEL was on when I started it till I arrived at work but when i went to start it up some hours later, the light was no longer on. So far all Ive done to try to fix the problem is I replaced the spark plugs, but this didnt change anything. Anyone who has had this problem know any solutions? Thank you in advance, this is my first time posting on this forum
11-24-2013, 06:14 PM
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Year: 1998 Sport
Model: Cherokee
Engine: 4.0
If it didn't start until you changed out the valve cover I would suspect that you may have bumped something. Check all the plugs and vacuum line and see if any of them came loose also check the vacuum hoses for cracks. It is very easy to cause other problems when working on these older vehicles just by bumping something.
11-24-2013, 06:25 PM
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I took a look already and didnt notice anything seeming to be out of wack but I will check again in the morning and look a little closer. When you say vacuum lines are you referring to the ccv's? sorry im a beginner so I dont know all that much yet
11-24-2013, 06:39 PM
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Year: 1999
Model: Cherokee
Engine: 4.0
Yup, you have had a check engine light so you DO have a stored code. That code must be pulled for clues and guidance. Use the technology provided to you by your Jeep; anything else is guesswork.
Retrieving codes on your 94 is very easy. Here is the procedure. Report back what stored codes you have for advice.
------------------------------------------------------------
Retrieving OBD codes on the Jeep Cherokee (XJ) OBD1 Models: 1991-1995
1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost.
NOTE: A "5-5" will always occur to signal the end of the sequence. Some will flash the "1-2" code indicating a recent battery disconnect even if you haven't done it. Ignore these two codes, and mark down all others.
Retrieving codes on your 94 is very easy. Here is the procedure. Report back what stored codes you have for advice.
------------------------------------------------------------
Retrieving OBD codes on the Jeep Cherokee (XJ) OBD1 Models: 1991-1995
1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost.
NOTE: A "5-5" will always occur to signal the end of the sequence. Some will flash the "1-2" code indicating a recent battery disconnect even if you haven't done it. Ignore these two codes, and mark down all others.
11-24-2013, 06:41 PM
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I'm not sure what codes, I was going to go get it read at my local shop after work but it was no longer on. will it still spit a code if the light is no longer on?
11-24-2013, 06:45 PM
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Year: 1999
Model: Cherokee
Engine: 4.0
Absolutely YES. These are called "stored codes". Retrieve the codes using the technique I just posted; you do not need your local shop. Will take you all of 10 minutes.
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11-24-2013, 07:07 PM
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34: speed control servo solenoid
41: Alternator field control circuit open or shorted
Where do I head from here?
11-24-2013, 07:33 PM
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Year: 1999
Model: Cherokee
Engine: 4.0
Do you have a voltage gauge on your dash? If so, what does it read at idle? You should have about 13.5 to 14.4 volts on either the dash gauge or tested with a meter at the battery.
I'd start with the alternator. Low available voltage can create fits for the engine management system and that can mean many driveability symptoms.
11-24-2013, 07:48 PM
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The code 41 is a failing alternator. It is one of the codes that is almost always accurate.
Do you have a voltage gauge on your dash? If so, what does it read at idle? You should have about 13.5 to 14.4 volts on either the dash gauge or tested with a meter at the battery.
I'd start with the alternator. Low available voltage can create fits for the engine management system and that can mean many driveability symptoms.
Do you have a voltage gauge on your dash? If so, what does it read at idle? You should have about 13.5 to 14.4 volts on either the dash gauge or tested with a meter at the battery.
I'd start with the alternator. Low available voltage can create fits for the engine management system and that can mean many driveability symptoms.
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