[CrimsonFkr]

Can’t figure out what’s going on with my engine. I’m getting spark and gas and I have compression. All the coil packs are brand new along with the spark plugs. I’ve changed out an O2 sensor because it was throwing a code. It started off with Cylinder 3 and 4 and then the Cylinder 4 misfire went away. Cylinder 3 has continued to misfire and now when I put the computer on it says Cylinder 6 misfire. Could it possibly be the EGR valve or the ECU?

 

[jeremyfagre1976]

Could possibly be bad fuel injectors I had the same problem with my 02 Pontiac grand prix

 

[Toxic OJ]

Can’t figure out what’s going on with my engine. I’m getting spark and gas and I have compression. All the coil packs are brand new along with the spark plugs. I’ve changed out an O2 sensor because it was throwing a code. It started off with Cylinder 3 and 4 and then the Cylinder 4 misfire went away. Cylinder 3 has continued to misfire and now when I put the computer on it says Cylinder 6 misfire. Could it possibly be the EGR valve or the ECU?

Resets the computer system. Do a cold restart. Unsure how to do it, check out the video for help.

 

[Nitroman11]

Can’t figure out what’s going on with my engine. I’m getting spark and gas and I have compression. All the coil packs are brand new along with the spark plugs. I’ve changed out an O2 sensor because it was throwing a code. It started off with Cylinder 3 and 4 and then the Cylinder 4 misfire went away. Cylinder 3 has continued to misfire and now when I put the computer on it says Cylinder 6 misfire. Could it possibly be the EGR valve or the ECU?

You note you have compression. Have you checked each cylinder with compression test? Are the readings consistant?
I had a 4.0 with readings over 200lbs except Cyl. 1 was 194. Turned out after doing everything you have done plus injectors and rocker assemblies I had a bad cylinder. Was told by dealer it was common on 3.7l but nothing showed on the 4.0l. Loved the truck, 101000mi crimson red and $4000 plus of add ons. Broke my heart to trade in but $4500 for new engine wasn't worth it. Hopefully your issue is not that. Good luck.

 

[Nitroman11]

You note you have compression. Have you checked each cylinder with compression test? Are the readings consistant?
I had a 4.0 with readings over 200lbs except Cyl. 1 was 194. Turned out after doing everything you have done plus injectors and rocker assemblies I had a bad cylinder. Was told by dealer it was common on 3.7l but nothing showed on the 4.0l. Loved the truck, 101000mi crimson red and $4000 plus of add ons. Broke my heart to trade in but $4500 for new engine wasn't worth it. Hopefully your issue is not that. Good luck.

Also...my miss cleared after 500 rpm's in beginning, to a year later 2500 rpm.s before it cleared. which means at 65mph, it would miss, clear and miss again.

 

[DaveM]

It could be your Crankshaft position sensor is going bad.