01 grand cherokee P1391 - JeepForum.com
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post #1 of 50 Old 09-07-2019, 04:40 PM Thread Starter
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Wj 01 grand cherokee P1391

Hello, new to the forum! Let me begin by saying i purchased this jeep yesterday. It has 213k on the body, with the 4.7 being rebuilt with only 63k on it. The previous owner stated he had 4 different mechanics tell him it was in fact the PCM causing the issues. I am having issues, While driving, the jeep is stuttering and completly stalling with red lights/stop signs. Will also shut off with a surge like motion when trying to stop. The jeep always starts right back up with no hesitation. I keep getting code P1391 on the obd2 scanner. Ive been researching the horror stories on this issue. None of the electronics seem to be acting up in the cab. Whats the chance these issues are coming from the PCM? Trying to find a reason other than the pcm before i purchase one to replace the one in the jeep. I have taken the one in the jeep out and it is corroded pretty badly on the back side. The connectors seem to be secure and fitting well. Wiggling them make no difference with the jeep idling. I did find some wires with the insulation scraped/burnt off on the left side of the engine block just in front of the starter. It was a black/orage wire, with another black wire looked like. From my research it seems to be the dimmer light wire. Another thing in the scanner, it shows the ignition advance jumping around. And everytime its about to die that drops. Then jumps back up. The jeep seems to run well, other than this "Miss"/hesitation. I will be replacing the Camshaft position sensor tomarrow. Does anyone have any ideas as to what i could be dealing with? thanks!

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post #2 of 50 Old 09-07-2019, 04:54 PM Thread Starter
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this is the wiring i was talking about, these wires are grounded to the left side block; just in front of the starter. i will also upload a video of the rpms dropping and when they drop is when i get the missfire/hesitation, going down the road its a constant jerking feeling.
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post #3 of 50 Old 09-07-2019, 04:56 PM
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P1391-INTERMITTENT LOSS OF CMP OR CKP

Ideally looking at live data might want to check cmp ckp sync
Stacking and observing the wave forms from CMP and CKP would help spot a missing signal.

WAG seeing the ignition timing jump - might want to concentrate on CKP - try A new jeep CKP sensor,

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #4 of 50 Old 09-07-2019, 05:24 PM
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confusion -- starter is located on RIGHT (passenger) side of eng.

Is that an o2 sensor ?
and can you see all wires and colors?
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When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #5 of 50 Old 09-07-2019, 06:42 PM Thread Starter
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Jtec, Thanks for the response. I have no equipment to check the wave signals i did see it done on youtube. And you are correct on the starter being on the passenger side. There is infact an o2 sensor very close by those wires. But not directly involved with those wires? if thats the right word to use? Sorry im not very intellectual when it comes to these things. I will deffinatly look into the CKP sensor. The wires that are either burnt or scraped; the best i could tell is its the black/orage stripe wire, with a plain black wire. There is another set of wires in a completely different bundle, (these wires looked fine) but they are connected with the same bolt as the burnt wires. I traced those back up to the harness thats got the battery wires included in the bundle. I apologize for my terminology. I tried to upload a video of the jeep running, but for some reason it would not let me post it.
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post #6 of 50 Old 09-07-2019, 09:55 PM Thread Starter
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Am i checking the resistance of the Crankshaft position sensor correctly?
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post #7 of 50 Old 09-08-2019, 04:39 AM
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Burnt and damaged wires are a major red flag and probably the first thing you should look at before doing too much or spending too much money.
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post #8 of 50 Old 09-08-2019, 07:26 AM Thread Starter
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Burnt and damaged wires are a major red flag and probably the first thing you should look at before doing too much or spending too much money.
JGCJ, Those specific wires are spliced together at the connector correct? so they wouldnt make any difference ift hey were touching right? I still plan on taping them up just for good measure. Please correct me if im wrong.
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post #9 of 50 Old 09-08-2019, 08:11 AM
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are there any other codes?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #10 of 50 Old 09-08-2019, 08:21 AM Thread Starter
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No the p1391 is the only code im getting
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post #11 of 50 Old 09-08-2019, 08:43 AM
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Quote:
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Quote:
Originally Posted by JGCJeep View Post
Burnt and damaged wires are a major red flag and probably the first thing you should look at before doing too much or spending too much money.
JGCJ, Those specific wires are spliced together at the connector correct? so they wouldnt make any difference ift hey were touching right? I still plan on taping them up just for good measure. Please correct me if im wrong.
I’m not sure exactly what wires they are or what they’re doing. It would be wise to verify and check before moving forward. Most wires are not spliced inside a connector.
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post #12 of 50 Old 09-08-2019, 09:01 AM
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they are ground wires which are spliced into the same ring connector on the block. with it looking damaged, I would repair the wire first and see if it clears the fault code.
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post #13 of 50 Old 09-08-2019, 09:19 AM Thread Starter
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From my research the wires that are messed up one site said they were ignition wires inside the ignition harness, and one site said they were dimmer light wires. If i could see them better and clean them off it would really helo to identify the colors better. My arms are too big to reach in there, having to go between the tie rod to get too it, its at ground 103 or something like that according to the charts ive seen
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post #14 of 50 Old 09-08-2019, 02:15 PM Thread Starter
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So after replacing The Crankshaft and Camshaft position sensors still no change. Still getting code p1391. Ignition advance is still jumping around everytime it stutters. The pictures below show the Ignition Advance jumping around, each photo shows the next number the scanner gave me. Does this model jeep have the ignition control module?
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post #15 of 50 Old 09-08-2019, 03:07 PM
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Just my opinion, but I would verify what those damaged wires do or just fix them. That is a red flag of an issue. It’s something that is damaged. Alldatadiy has decent prints and is not expensive.
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