Code p1391? -
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post #1 of 5 Old 05-02-2013, 12:23 PM Thread Starter
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1996 ZJ 
Join Date: Apr 2013
Location: Clearwater
Posts: 14
Code p1391?

Just took my ZJ over to an auto shop to get the codes tested. It came up as P1391. I have heard many different things as to what this means. The man at the shop said that it could not be the cam shaft or crank shaft because if it was it would have pulled up more codes. Another thing i was told was that it could be something with the distributor cap. But i recently just replaced the distributor cap and the spark plugs. What else could this be? The jeep has been doing this weird thing where it is almost like hoping forward while you drive and when you press the gas hard it backfires and doesn't accelerate that much. Could this be related to the code?

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post #2 of 5 Old 05-02-2013, 01:17 PM
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1996 ZJ 
Join Date: Apr 2013
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P1391 - Intermittent loss of CMP or CKP

Don't rule out either of those sensors. You can feel around for the CPS wire and see if it's broken, a couple times mine got chewed on by mice, so I could repair the wire instead of getting a whole new CPS. I didn't get any other codes besides 1391 though.
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post #3 of 5 Old 05-02-2013, 11:09 PM Thread Starter
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1996 ZJ 
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What is a CPS and where can i find it?
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post #4 of 5 Old 05-03-2013, 12:03 AM
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1995 ZJ 
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CPS = CKP, crankshaft position sensor.

You will find this sensor on the top/RH side of the trans bell housing where it mounts to the engine. It is basically behind and below the back side of the passenger side valve cover. It kind of sucks to get back there and replace one but with a little patience its not too bad.

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post #5 of 5 Old 05-03-2013, 09:40 AM
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1997 ZJ 
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I thought cps was cam position sensor, also the halo sensor or distributor pickup, the round black sensor that sits under the rotor inside distributor?

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