Misfire CEL with no symptoms

JLutes559

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May 8, 2025
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California
I have misfire codes, P0300, P0305, P0306 on my 2001 Sahara with no modes and A/T. Happens regularly at about 3500-4000 rpms. Vehicle runs great except for it going into limp mode with the CEL light initially comes on. But once decreasing rpm’s, limp mode stops but cel remains. Again vehicle runs great except, no noticeable change with how it runs. Have replaced numerous things to include coil pack, crankshaft sensor, plugs, cam sensor, TPS, have had the head checked and compression checked, all fine. Mechanic, to include the dealership are all at a lose. Have even had wrangler fix check PCM, it’s good. Any help would be greatly appreciated.
 
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I have misfire codes, P0300, P0305, P0306 on my 2001 Sahara with no modes and A/T. Happens regularly at about 3500-4000 rpms. Vehicle runs great except for it going into limp mode with the CEL light initially comes on. But once decreasing rpm’s, limp mode stops but cel remains. Again vehicle runs great except, no noticeable change with how it runs. Have replaced numerous things to include coil pack, crankshaft sensor, plugs, cam sensor, TPS, have had the head checked and compression checked, all fine. Mechanic, to include the dealership are all at a lose. Have even had wrangler fix check PCM, it’s good. Any help would be greatly appreciated.

I'm almost willing to bet it's a short in the wiring harness somewhere.

Replace the entire wiring harness or spend week tearing it apart and going through every single wire. I'll bet you'll find your culprit there.
 
I'm almost willing to bet it's a short in the wiring harness somewhere.

Replace the entire wiring harness or spend week tearing it apart and going through every single wire. I'll bet you'll find your culprit there.

That has been a thought. Is there anyplace that sells wiring harness.
 
Not brand new. @Wranglerfix often times has some. I’d check with him first and see. Another person who may or may not have some spare wiring harnesses is @mrblaine.

Thank you. I will definitely check with them. The crankshaft sensor isn’t OEM but I have replaced it twice, with no change in the outcome. Finding an OEM has been challenging.
 
Thank you. I will definitely check with them. The crankshaft sensor isn’t OEM but I have replaced it twice, with no change in the outcome. Finding an OEM has been challenging.

Yep it’s getting to be near impossible these days. Best bet is to go with a high quality aftermarket brand.
 
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I have misfire codes, P0300, P0305, P0306 on my 2001 Sahara with no modes and A/T. Happens regularly at about 3500-4000 rpms. Vehicle runs great except for it going into limp mode with the CEL light initially comes on. But once decreasing rpm’s, limp mode stops but cel remains. Again vehicle runs great except, no noticeable change with how it runs. Have replaced numerous things to include coil pack, crankshaft sensor, plugs, cam sensor, TPS, have had the head checked and compression checked, all fine. Mechanic, to include the dealership are all at a lose. Have even had wrangler fix check PCM, it’s good. Any help would be greatly appreciated.

First thing I would do is get the rig on a scanner that can adjust the cam crank timing and set that to zero. Keep an eye on when this happens, I suspect that it is more prevalent going either up or down hills.
 
This might help finding a scanner...


-Mac
 
First thing I would do is get the rig on a scanner that can adjust the cam crank timing and set that to zero. Keep an eye on when this happens, I suspect that it is more prevalent going either up or down hills.

Hey, love all you do, but curious, where would someone find a place that can do this? Is this a Jeep shop? A random dealer? For what it's worth, I'm in the Charlotte NC area. Any tuning ideas on this coast?

Absolutely reaching out to you for brakes soon, particularly each time I actually have to stop on mine w/ 35's. Your website is a bit overwhelming for some of us though, any tips for what best for an '05 Rubi TJ on 35's?

Apologies to https://wranglertjforum.com/members/jlutes559.48437/