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Misfire at idle, skip or miss while accelerating, cps failure

Cmank788*

NAXJA Forum User
Location
CO
Not sure what to do next trying to fix a bad idle issue. Having all the symptoms of a failing crank sensor like engine vibration, poor idle wont die but almost does when warmed up, under load at higher rpms it will skip or miss for a split second and continue accelerating, speedometer and mileage have stopped working entirely, engine is deffently holding back all together much like its misfiring but when cold started engine sounds good cannot hear or feel a miss until it has warmed up. The issue is constant it will skip or miss every time when warmed up. So here is what I've done so far with no luck have not fixed the problem.

93 XJ H.O. 4.0 AX-15 manual trans
New crankshaft position sensor
Champ copper spark plugs gapped 0.35
Spark plug wires
Distributor cap and rotor
New upstream 02 sensor
Check and repaired all the grounds I could find.
Cleaned all electrical plug connections
Checked fuel pump
New fuel filter
New fuel pressure regulator
Pulled fuel rail cleaned injectors and set with new O rings
Ran seafoam through the throttle and gas tank.

This problem started soon after I had changed my clutch, when reinstalling the cps I had forgotten to place the rubber shroud in the hole where the cps goes into the bell housing. Drove excellent for a week no issues then we had a very harsh freeze that happened very quickly, next morning the jeep would not start at all, cranked all day but no spark. I pulled the cps cleaned it and reinstalled with rubber shroud in place. At this point the jeep started right up but now had all the issues. So first thing got a new cps sensor and went from there with the rest of this goose chase. It's hard to decipher whether it's an electrical issue, grounding out, fuel delivery so I've tried to address all possibilities. Starting to think the PCM might be the problem because I've seen no improvement from the new sensors when the old ones were toast. Unfortunately I am about stumped and dont want to spend anymore money until I know I'm fixing the problem. Any ideas would be greatly appreciated thank you.
 
CPS failure typically results in random stalling, or a no-start condition. Bucking, skipping or missing might make one suspect fuel pressure/fuel delivery issues, or faulty OBD engine sensors.

You should never randomly replace parts. You should always have proper diagnostics and testing that shows a specific weakness or failure. Is or was the Check Engine Light ON ?

Have you tested all of the engine sensors, the coil, and the fuel pressure ? Have you inspected the O2 sensor wire harness and CPS wire harness for damage that may have occurred during the clutch replacement ?

What brand of O2 sensors were installed ? What brand of OBD engine sensors were installed ? Most auto parts stores sell cheap crappy Chinese made parts, some that even come with a "Lifetime Warranty". These parts are poorly manufactured and/or made from inferior materials. They are often out of specification, or even failed, right out of the box. The ones that are not faulty many times will have a short service life before they fail. Always buy top quality replacement parts and genuine Jeep engine sensors. Numerous threads detail long and frustrating searches for a "problem" that ended up being cured simply with genuine Jeep repair parts. Cheap parts are cheap for a reason.
 
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