JoopPoop

Hey guys. I have the horrible misfire that I cannot figure out for the life of me. I bought a 99 Jeep Grand Cherokee w/4.0 from auction. Has a misfire on CYL #6. Idle is high (around 1200-2000RPM)

I started with replacing the coilpack rail and spark plugs, reset the CEL and misfire was still there. I then realized that the injector was not working on #6 so I swapped out the injector and reset the CEL, injector works but stops working when the CEL comes on.

I then tested the voltage of the injector plug and it was the same as the rest so I proceeded to ohm the ground wire from the injector plug to the battery and it was fine. I checked the grounds around the engine and sprayed around the intake and hoses to see if the idle changed, nothing.

I swapped the throttle body along with the IACV and TPS to just see if i could get the idle down. It helped a lot and stopped revving randomly to 2000rpm but still stays around 1200RPM. Got a new TB gasket (dont worry).

Last thing I did was dry compression test hoping that it would be low on CYL #6 due to a burnt valve but its the highest CYL PSI out of all 6.

#1: 100 PSI

#2: 105 PSI

#3: 120 PSI

#4: 115 PSI

#5: 125 PSI

#6: 130 PSI

Any advice would be great! I am trying to get this car running good as a present to my mother as she always loved Jeeps and always wanted one. Thanks!