Backfiring in closed loop Jeep Registry
Previous Jeep WJ Grand Cherokee

Backfiring in closed loop

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So I’ve got a 2002 wj 4.0l. Runs good I. Open loop when cold but when it goes into closed loop and warms up it backfires and stutters and sometimes dies. Usually only backfires and stutters when I’m heavy on the throttle so if I drive it carefully I can keep it running. Replaced almost everything in the book. Fuel injectors, battery, alternator, pcm, coil pack, passenger side wiring harness, NTK O2 sensors, fuel regulator/filter, spark plugs, coolant temp sensor, thermostat, fuel pump relay. It’s not throwing any codes. It does have an over heating issue that I haven’t got to yet. The temp gauge will read 210 degrees but my scanner will read 223. The guy who had the Jeep before me didn’t seem to be the smartest (lots of loose bolts everywhere) so I’m thinking he could have put an aftermarket fuel pump in that could be causing problems. Let me know what you guys think, thanks


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