Jeep jerking like a misfire, code P1391
#1
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Year: 2000
Model: Cherokee
Engine: 4.0L
Jeep jerking like a misfire, code P1391
Hi all,
2000 XJ, 210k miles (~170k on the engine), auto trans 4x4
A few weeks ago I was towing my jetski down the shore, about 75 miles one way, when I felt a few random jerks while driving. Pretty much like a dead miss but just one and then nothing for a while. Only happened maybe 5 times total on the whole trip.
Just took it to the store however, maybe a 15 miles round trip, and it was doing it alot more. It definitely feels like a misfire, it idles fine but under load it jerks and rpms bounce. The CEL came on on my way home, only code is P1391. I know for sure the CKP and CMP can cause misfires, but any way to tell which one it is? or just replace both?
2000 XJ, 210k miles (~170k on the engine), auto trans 4x4
A few weeks ago I was towing my jetski down the shore, about 75 miles one way, when I felt a few random jerks while driving. Pretty much like a dead miss but just one and then nothing for a while. Only happened maybe 5 times total on the whole trip.
Just took it to the store however, maybe a 15 miles round trip, and it was doing it alot more. It definitely feels like a misfire, it idles fine but under load it jerks and rpms bounce. The CEL came on on my way home, only code is P1391. I know for sure the CKP and CMP can cause misfires, but any way to tell which one it is? or just replace both?
#3
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Join Date: Aug 2015
Location: New Jersey
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Year: 2000
Model: Cherokee
Engine: 4.0L
Hey, yea it turned out to be the crank position sensor even though it wasn't that old. I replaced the parts store one with a Standard Motor Products one from rockauto. It's been in since last November with no problems, so I guess I'll see how long it lasts. If you have the cash they have actual Mopar sensors for $85.
#4
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Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
There are three sensors on the Jeep where you should not even THINK about using any aftermarket sensors:
Better yet, just still with the good stuff for all sensors.
- Crankshaft position sensor
- Camshaft position sensor
- O2 sensor
Better yet, just still with the good stuff for all sensors.