Superclyde

Definition: CMP or CKP signal intermittent condition.
Explanation: The ECM detected the actual CMP position disagreed with the expected CMP level.
Probable Cause: Timing belt or chain stretched or jumped, or defective CMP sensor.

This is the code my 99 cherokee is giving when the engine light comes on. It is misfiring intermittently to frequently. I have replaced the timing chain, crank gear and cam gear along with the crank sensor. After installing these, it gave the same code again, almost immediately.

SIDE NOTE: The cap, rotor, wires, plugs and injectors have also been replaced trying to eliminate this misfire. I have also checked and cleaned all grounds that I know of. Fuel pressure is good.

Any ideas? Pretty much going broke chasing this problem, but love my ride. I was thinking maybe a worn distributor gear or a worn bushing in the distributor, causing the timing to misfire?

Thanks to all who read this and reply, I find this site a wonderful source of information. Thanks again.

freegdr

possible dist it selhttp://https://www.cherokeeforum.com...e-p1391-19355/

Gee oh Dee

Could be crank sensor.

tjwalker

P1391 can be caused by EITHER a bad crankshaft position sensor OR a bad camshaft position sensor (or their circuits).

I'd spend some time working on the camshaft sensor, testing or replacing it.

Where did you get your replacement crank sensor from? The reason I ask is that there is no lack of people having issues with some (not all) aftermarket crank sensors. It is one of the things that I purchase ONLY from the Jeep dealership.

SeriousOffroad

Every P1391 I've dealt with has been the result of an incorrectly indexed distributor.

Superclyde

Sorry I haven't replied sooner but you know how that goes.

To answer a few replies, I got the crank sensor at Autozone.
As stated earlier, it has been installed but did not fix the problem.

I am going to replace the entire distributor today, I really think that this is the problem. I will keep you posted.

thanks.

Countryboy 73

I'm getting the same code with my 96 Cherokee. I've replaced the cam shaft sensor once and the crankshaft sensor twice. Now it's backfiring through the intake at low rpms while accelerating. I was thinking about checking the timing chain and gears but I've never messed with that before so this part is all new to me. Any helpful advice is greatly appreciated. Thanks in advance.