Intermittent P1391

[TurqouiseJeep]

I wanted to share my experience with a p1391 just in case it helps someone else. My jeep has been experiencing intermittent loss of power/bucking in several phases of driving - on started up, driving on the highway, and idling at stoplights. It was always super random and would only last for 1-5 seconds. I never had a CEL and it felt like a misfire, but scanning never revealed any codes. As it got hotter out the problem escalated a bit to where it would happen on most start ups and a couple of times per drive, where before it was only once every couple drives. I finally caught a pending code after one of the more severe episodes which showed p1391. I’m assuming because it was so infrequent this pending code was never confirmed and would eventually clear on its own.

Before going out and swapping the cam and crankshaft position sensors, I figured I’d give the connectors a once over to make sure they mated solidly, there wasn’t any gunk, or any damaged wires. Glad I did that, because here’s what I found:

I purchased a new connector on Amazon with pre installed pigtails for ~$10.
https://www.amazon.com/dp/B0DP31JZMG?tag=wranglerorg-20

I’ve only been able to start and idle after replacing and hooking everything back up because I’m still working on a few other things, but so far every start is consistent and I’m not getting an intermittent slow start like I would before. The true test will be taking it for a drive on a hot day since that exasperated the issue before, so I’ll report back if this didn't end up being the fix.

 

[Chris]

Thanks for sharing this. It will certainly help someone in the future, but even moreover it highlights what myself and others are always pointing out. That is that when you get a vehicle of this age with electrical / sensor issues, more often than not it ends up being a short somewhere in the wiring harness or a bad connection / connector.

Often times people spend countless amounts of money buying new sensors only to find that that didn't solve their issue. Rarely do people decided to take apart the wiring harness and inspect things.

I look forward to hearing back with an update!