1991 jeep Cherokee replaced plugs,cap,rotor,wires,distributor,CPS checked out okay,getting spark from coil to distributor ,only cylinders 3-4 have spark from cap,???

 

Did it run before you did this work?

 

Hello, new to forum. Need help. I recently had 93 xj 4.0 hard crank and then run poor then lost spark. Cam sensor changed at mechanic. Ran fine to the house the Did same thing again, no spark just turned over. Intermittently would crank fine. I mean like no start then 10 min later crank fine. Anyone know of any obvious wiring issues that may cause this?? I’m lost. Have owned the Jeep for two yrs and this is new symptom. If this is in the wrong spot I apologize, will learn the ropes.

 

How are the rotor and cap? Ensure that all of the plugs' wires have good contact.

 

Yeah those are all good. Replaced distributor with cam sensor swap. When it loses spark, diagnostics shows a crank sensor response but no cam response. That’s when the mechanic changed cam sensor and it worked. But next same day same symptom intermittently. I shook wires while it was running trying to get it to miss or stall but nothing. Could a bad ground somewhere cause this? Maybe I’ll redo the grounds. Faulty ecm?

 

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We found out why it didn't want to run. It was the coil pack(s). We started to blindly replace parts like the spark plugs and it ended up being one of our 3 coil packs. She runs and we are going to do the brakes on it.