Hi, I'm new to this forum but hoping for some help with a problem in my daughters 2001 Jeep Grand Cherokee 4.0. She told me a few weeks ago she was having a problem where the jeep would stall or just shut down when she was driving. After reading forums it looked like a common crank position sensor problem. I picked up a new crank sensor at advance auto and installed it. After The install I went to crank the jeep over and it sounded like it was way out of timing. I went back to that sensor and loosened the bolt and pushed the sensor all the way in and tightened the bolt. It started. Aggravating who uses a slotted hole for a precision set on a sensor. A few days later she is driving it and gets a check engine light and it starts flashing. The flashing stopped but light remains on. It seems to be running smooth. You can make it start flashing and notice a major misfire if you jump on the throttle hard from a stop? I pulled the codes and getting a po300 pO305 and random other cylinder misfires. I've erased codes and it keeps occurring. I've changed plugs, coil rail, (not related but problems also battery and starter). Still having the same problem. Any insight where to go from here. Seems many people have changed additonal sensors and still doesn't fix the problem.

 

I have a similar issue with my wife's where it idles very rough and throws misfire codes, I have done a lot of research and have seen a lot about connections in the computer that break and will cause this issue. There are a few vids on YouTube on it where people have soldered the connections and replaced the camshaft position sensor and this has solved their issue. I myself have not tried it however I intend on trying it soon. Maybe if anything this is an idea for you to try.

 

Tonight I did a compression check on the cylinders and checked the resistance on the fuel injectors. Cylinders 1,2,4,5,6 had 170 PSI. Cylinder 3 was 162 PSI. All the fuel injectors measured around 12.5 ohms. Seems the cylinder head is not the problem in this case. Still major misfire going on.

 

When you changed the coil rail did you happen to replace the rubber boots that look like cow udders? The reason that I ask is that if you re-used them, they could be the cause of the problem. If these boots have carbon tracking on them, they cause a misfire condition. So, if you did re-use them, I would go out and buy new ones. I have seen this problem on a multitude of vehicles and replacing the boots cured the problem.

 

The new coil rail had new boots and springs as part of the rail. I'm gonna try and change the crank sensor I got from Advance auto to an OEM mopar part. Seen a few forum post saying the aftermarket sensors are junk. The jeep was running decent before I changed the crank sensor. It was stalling and shutting down randomly when my daughter was driving. I read post and everything pointed to the crank sensor being on it's way out. Thats what prompted me to change the crank sensor.

 

Yes, I'd use a Mopar part. The CPS is a Hall-effect switch and needs to be constructed of quality materials. Case in point; I bought a premium NAPA oil pressure sensor that was made in Mexico only to have it never read anything but 30 psi EVER! I spent $20 more for a Mopar part and it works like it should.

The CPS should come with a felt button on it that sets the spacing correctly, then tears off when you start the engine.

 

So I changed the crank sensor and cam sensor over to mopar parts. The jeep started right up and has been driven on and off for 3 days now with no check engine lights and running normal. I wish I saved the box to the piece of junk sensor I got for $50- at Advance auto. Highly recommend genuine mopar parts for these sensors. Thanks to all for the help.

 

There ya go! Thanks for posting your fix! It's bound to help others.