Just picked this Jeep up and the guy put the '93 motor in and it will not start. It is a 1990, no spark. I am think he didnt change the flex plate when he did the swap. Which is causing the cps to not read. That being said is this just a sensor swap? The mount and plug seem to be the same, or do I need to change out the flexplate? Any help would be great!

 

AFAIK the 90 is a "renix" motor and the 93 was a HO, do you know if he changed the CPU or anything else? ...Tj

 

If he still is has the Renix set up on it dan does not have the right flex plate on you have to replace the flex plate. If it his the right flex plate on it check all grounds even the grounds at yhe sensors. I had a broken grond at the knox sensor that made it not have spark.

 

He did not change out the cpu. I do know that it does have to renix cps on it still, but not sure how to tell if it has the renix flexplate or the HO style flexplate. Dont want to pull it all apart only to find that it has the correct one in it... I have verified the CPU to be good I pulled it out and tested it in my 88 comanche and it started it right up no problems. But on the Cherokee, it turns over great just no spark at all. Thanks for the help guys!

 

The Renix flexpleat hole all the way round the the flex pleat. the HO one longer spots that that do not have holes. I got both I will take pics of them and post them.

 

Did you check grounds?