Question about 2000 Jeep Cherokee
I have a 2000 Jeep Cherokee with the 4.0L, Auto Trans, 4X4, that needed a head gasket. I installed the head gasket, solved my cooling problems, but at the same time as the head problem was going on, I noticed a MIL on. Scanned codes with my Modis, found P0300, Random cylinder misfire. I figured it had something to do with getting coolant in the cylinders, or loss of compression due to the head problem, so I fixed the head. After the fix, I got a cylinder 6 misfire code. Then two more codes popped up, regarding a miscommunication between the PCM and TCM, thru the CCD Bus. I also noticed that I couldn't connect my Modis to the computer using the Chrysler specific setting, I had to go thru Global OBD II. Now, I've confirmed that the injector and harness are OK, replaced the plugs with genuine Mopar plugs (gapped correctly, of course), checked the coil strip and found it to be firing OK on all cylinders, and checked and confirmed that the CKP is okay, and the CMP is okay as well. Compression on all six cylinders is even and normal. No intake manifold leaks, and when I had the head off, I had it checked for leaks and cracks, and deck warpage, and found all to be OK. Also cleaned all the carbon off of the combustion chambers, took the valves out and cleaned them off as well, so I know that it is not a problem in the valvetrain. I cannot figure this problem out! I retrieved freeze frame data that stated when the code was registered, the vehicle was at 65 MPH, etc. but the engine speed data (RPMs) read 0. And the vehicle had never stalled on me. But the tach works fine. What exactly is going on here? I just wish I had some answer, everyone seems to want to offer easy fixes to me (change the plugs, etc.), but I have checked this vehicle out thoroughly and cannot detect a problem. I am very hesitant to declare a PCM bad, since all of its reference signals are OK, and it has good grounds to it. I am an ASE Master Certified technician, and very skilled at electronics, yet this problem escapes me. I'm more or less looking for someone else's opinion on what it could be. Please email me if you can, my address is MCAuto87@live.com
Since freeze frame data indicated 0rpm @ 65mph i could only assume the ckp or wiring to it has an intermitten open in the circuit. That or a bad PCM. I would try and solve the communication issues first and see if the misfire continues.
Posted on May 09, 2009
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Posted on Jan 02, 2017
SOURCE: OBD II Problem
the code refers to the crankshaft and camshaft sensors, the crank sensor has a higher failure rate, but usually the engine will not start or run when it does. the camshaft sensor can fail and the engine will still run. I would check the connections to each sensor for damage or corrosion, the system has lost signal from one of them, if you check them with an OHM meter they should not measure open
Posted on Apr 08, 2009
SOURCE: 96 dakota p1391 error
intermittent loss of ckp or cmp.problem is in the distributor.make sure rotor not loose or distributor hold down bolt loose.camsensor on the distributor.also check to see if crank sensor is loose and out of adjustment.
Posted on Jun 07, 2009
It means that intermittently you are losing the signal from your camshaft position sensor (CMP) And you are also losing the the crankshaft position signal sensor (CKP). these are magnetic or hall effect sensors that go out sometimes and are necessary or you could have a poorly running vehicle or it may not run at all. hope this helps you out!!!
Posted on Jul 09, 2009
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