Overview: '97 Cherokee with the 4 litre AW4 tranny, 160k miles, NP231 transfer case.

My Jeep hasn't been in proper running condition for a long time now. It started when I was driving it home one day and going around a corner it just stalled out and died for no reason. After waiting several minutes I was able to start it and drive it home, before this there were no real problems I was ever having. A couple days later when I got back in to drive it, my Jeep died thirty seconds after starting it so I brought it back home.

I checked the codes, and ended up changing the coolant temperature sensor, and that got it to the point where it ran again, but now it started doing this thing where it would bog down and kick really hard if you tried to hold a steady speed on the highway. I've changed the upstream 02 sensor, Crank position sensor (Mopar brand replacement), Cam sensor, throttle position sensor, and lastly the distributor. After changing the distributor it is giving me a rough start, but will idle near perfectly. When I rev the engine it doesn't want to go over 2k and starts missing horribly! Through this whole process I've had the P1391 code (loss of crank or cam position.)

A friend of mine seems to think it's timing chain, but I don't think that it would degrade so suddenly like that. I believe the distributor timing is correct, because it was acting like it was 180 out when I first put it in, and wouldn't start so I rotated it.

Any ideas or help, hell if anyone can tell me what they think it is NOT would help! I'm just about to the point of wanting to take it into the Chrysler dealer.. I have only taken a vehicle in once and would really love to be able to fix this myself!

Thanks for any help

 

I used to have the same problem you had with misfiring horribly above 2K RPM for me it was my fuel pump went out it wouldnt build pressure. I would start with checking your fuel pressure it should be at around 49 PSI

 

You really need to focus on the circuit the code is tripping for. While codes are sometimes difficult to interpret, the OBD system is VERY good and believable at pointing you to the correct circuit that is faulty.

Remember that these codes are not just for the sensors. They are for the entire "circuit", and that means connectors, wiring, etc.

I would try getting a can of electrical contact cleaner (even Walmart carries this), and thoroughly flushing the 3 connectors. The cam sensor connector, the crank sensor connector under the hood near the firewall / #6 injector and the connector on the crank sensor itself. Then add a dab of dielectric grease to the connectors before reconnecting.

If that doesn't help, you could have a wiring issue involved with one of those sensor circuits.

And in the event that you may have more than one thing going on here (don't laugh, and don't get tunnel vision here), I agree with 99 Purple XJ and would put a fuel pressure gauge on the schrader valve on the fuel rail to verify proper fuel delivery. For a 97, you should have 49 psi, plus or minus 5 psi. The fact that it really acts up at 2k could mean that it isn't supplying enough fuel at that point.

 

Forgot to mention, checked the fuel pressure and that came out good. I will have to give the contact cleaner a try. The wiring seems alright, but you guys do believe it should be something relating to that code though, correct?

 

I definitely do. It is rare (with the computer itself being an outside exception) where after we resolved a problem with an OBDII system, that it wasn't related to the particular circuit that it was setting the code for. Of course, things always make sense AFTER you find the root cause!

Good luck!

 

You are right brother! haha thanks for the reassurement! I'll try taking a look at the wiring for both systems tomorrow

 

Did you make any progress with your problem? I'm having a very similar problem, stuttering under medium acceleration, and I have the same P1391 code. I also have a P1398 code, which is so frustrating because I have replaced both crank and cam position sensors. Hope you solved your headache.