I have a 1991 Cherokee 4.0 that has been giving me a really hard time to diagnose. It cranks over fine but occasionally will have no spark. I have changed the CPS-Crank Position Sensor three times, Pick up coil twice, Coil twice, Distributor Cap and Rotor once, the entire Distributor once, Plug wires, Battery and terminals, cleaned all the ground wires body and motor, cleaned and made sure all connections are making good contact. I have run all the ohm tests on the CPS, Coil and Pickup Coil and always within specs. What am I missing??

 

You're in the wrong section, 93 was the first year for a Grand Chrokee. But it sounds like you may have a PCM problem.

 

When you have no spark, is that verified? From there have you checked to see if there is power at the coil? Maybe you are losing the power circuit to the ignition. check the fuse box (corrosion maybe), fuses (loose/corroded) and ASD relay for proper operation. Sounds like you have eliminated about everything but the power source, wiring and ECU/PCM

 

Thanks for the help!! I will double check the connections at the fuse box. Next time it wont start I will try swapping out the ASD relay. Thanks!