finneys98xj

My jeep is being a *****! It back fires between 15-2000 RPMs and acts like it backfires and lose power for a moment. Things I know it aint are CPS, coil, Dizzy, plug wires, plugs, battery, and I'm getting good fuel pressure. I need help guys please!

91Laredo

Have you checked your Throttle Position Sensor? my TPS was causing all kinda of problems in mine, (mostly backfiring) and 50 dollars later and a trip to schucks was all it needed.

a1racer

that could be it or maybe o2 sensor if the reading is bad it could be running rich

That Jeep Guy XJMJ

it may be a far off long shot, but my other 95xj that i recently sold had a similar issue, but it also wasn't starting very often.... it ended up being a section of the harness that connects to the alt, starter, and coil pack.... $20 replacement from a local parts yard.. the wires had just become defect for some reason, no wears, bear spots, or strip/cuts either

4.3L XJ

Finney

If you are backfiring, that means you are getting fuel where it is supposed to be. Your spark is temporarily quitting. Then when it comes back, the unburned fuel burns in the exhaust system. Since you have already done all that other stuff, my first thoughts would be the distributer pick up. I don't know how to test them, but I have had them go bad on me before and it is really the pits because they are hard to diagnose.

finneys98xj

the hold dizzy has been swapped out and the harness for it has been checked.

4.3L XJ

Finney, you are just no fun at all. I'm running out of options with this. Must be a Gremlin. Seriously though the only thing left then is the ECM

jd4x426

did you get a new or remanufactured dizzy some times on the remanufactured ones the pick up doesnt get replaced if it passes a 5 second bench it good or say they think i would check into that if it is a remanufactured job

finneys98xj

We swap dizzys off of a perfectly good running driving XJ with the same result. the other runs great with mine.

jd4x426

are you sure that you have a good spark maybe a weak spark is the culprit it has to be something ignition related because if its backfiring its getting fuel just no spark start checking each and every connection double and tripple check everything till you find it

finneys98xj

TPS didnt fix.
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A mech. couldn't even figure it out. he checked the wiring for a week also swapped coils and everything be no go. I trust this guy with my cars more than I would my self changing the oil.