jetmech52

My 2000 Jeep Cherokee 4.0 Liter (153,000 miles) started running rough and really cutting out above 55 MPH. No CEL. The next day it ran OK for about 10 miles and then started cutting out at high speed, again no CEL. It did the same again today and again no CEL. I put my code reader on it and got a P0204 and a P0304. Ideas?

tjwalker

Both of those codes indicate a problem with cylinder #4. P0204 is for the fuel injector and P0304 is a misfire. But both are for the same cylinder. So focus your efforts on this cylinder.

1. When did you last change spark plugs? What brand plugs are you running?

2. Are these the original fuel injectors?

3. Have you had to add coolant to your coolant reservoir lately? Not likely related, but I ask this question to anybody with an 00-01 that has problems with cylinders 3 or 4 because of the known cylinder head issue cracking between these cylinders.

Good luck and keep us updated!

BillyBoy

Is the oil foamy..? Cracks = foam. Have u kept up on the oil changes? Seaford might help. To the crankcase.

jetmech52

I found the problem with my 2000 XJ. The #4 injector coil was opening up when it got hot. When the engine was cold the injector had 12.5 ohms and when it got hot and the engine had started to misfire the injector read infinity ohms. Installed a new injector and it is running back to normal.

BlueRidgeMark

Good diagnosis work.

Thanks for the follow up!