I have a 2000 jeep cherokee classic 4.0 4wd auto, and I’m having an issue where It will crank but not turn over when hot. But starts runs and idles fine when cold. Also when it gets hot it completely dies when driving, like your turning the key off, doesn’t sputter or anything.
Does this sound like a bad Crankshaft position sensor??

 

Sounds almost exactly what my '00 did. Turned out to be the CPS.
You can read about my experience with it here:

https://www.cherokeeforum.com/f2/cut...riving-241745/

 

It sure could be. The #1 component susceptible to "heat related failure" on your XJ is the crankshaft position sensor. Testing may not be of any value unless you test it when it is in the NO START condition.

If you do end up replacing it, do yourself a big favor and buy a genuine Mopar unit from Jeep. Aftermarket crank sensor quality is very "hit and miss" with a whole lot of miss...

 

I just installed a new duralast crank sensor and I think it fixed my problem. However at idle my rpms Jump up a little bit, almost like your tapping the throttle, but I am not doing that.
Any thoughts?

 

It also has trouble keeping a good idle when I go from neutral to drive and start to drive on it. But once it gets to around 10mph all is fine and normal.

 

I was driving it some more and my CEL came on with the code p1391

 

"I was driving it some more and my CEL came on with the code p1391"

I think the Duralast Crank sensor is at fault.

I would focus in on the Camshaft Position Sensor (CPS) and Crankshaft Position Sensor (CkPS) circuits. Looking over all of the associated wiring visually and testing where appropriate with a multimeter. Clean all of the connections real quick. And then put a quality CkPS (Crankshaft) sensor in there instead of the Duralast one if all of the other checks out okay.

 

It's all spelled out right there. You ignored good advice from one of the most experienced Jeepers on the planet, and it isn't making you happy.

 

I already had purchased a new sensor before “one of the most experienced Jeepers on the planet” told me not to get anything but oem. I’m sorry, my XJ is my first vehicle and I’m just trying to work on it and learn. I’m glad there’s sights like this forum to help me. Now if anyone else had the same problem as me and they see this thread, they will know NOT TO GET ANYTHING BUT OEM.

 

Those less expensive aftermarket CkPS sensors sound like they are more bad than good a lot of the times.. right out of the box. The ones that are good when new may only remain good for a short while before they wind up causing similar issues to reoccur again... And for many people, this is when they end up replacing a lot of parts afterwards, as they believe the new CkPS could not be the reason since it had already been replaced. It cost them a lot of time and money when something like this happens to them. This is sometimes the point at which they show up on this forum when they are at their witts end with having already spent soo much of their time and money on attempting to fix the problem.

Hopefully, the Duralst sensor is the reason? It definitely sounds like it to me.

Would you mind reporting back here about it? If it was the brand new aftermarket Duralst Crankshaft Position Sensor, after all?

 

As the Mopar units run out and become more scarce there will be a need for an aftermarket unit that performs as well. I am working on this task currently. I have used the...
napa echlin: dead out of the box
Advanced auto encore: misfires
BWD: misfires randomly at operating temp
Multiple China specials: one ran great for about 5 years a few dead on arrival, the quality control is nonexistent.

The one that ive been working on has been looking very promising and is the only one with a 3 year warranty.

 

Which is why when I replaced my CPS a few years back said screw it and bought another Mopar on for "stock".
Be curious to see what you come up with.
Going to be for older Jeeps or '97 and up too?

 

91 to 01 covering 4 different connector types.

 

I ordered the same part off summit racing, and after a week of driving all seems good and normal. Thanks for the help.