Working on a 2002 Dodge Caravan with a 3.3 engine. Has 196K one owner miles. Mobil 1 since new. At about 170K I replaced all plugs and wires with factory parts as oart of maintenance. Had eye surgery so could not work on anything tedious for last few months. Recently had the owner take it to a dealer with a misfire code. Replaced #6 spark plug. About a week later, the code came back. Dealer replaced all 6 plugs and wires and number 6 injector. A month passes and codes read multiple cylinder misfire and bad coil pack. Replaced coil pack.

Eye better now and I can work to follow up but van still has cylinder misfire on #6 and I'm trying to play detective. Did a compression check. Cylinders 2 and 4 have 150-5 psi warm, 175 hot. Cylinder 6 is 130 warm, 150 hot so there is a 25 psi difference but a leakdown at 100 psi on 6 has 95% with normal hissing from crankcase. Did a lift test on each rocker arm. All 3 intakes show .380 lift so cam wear does not appear to be a problem. Spark appears to be a bit weaker on #6 but the car runs pretty well at highway speeds just misses at idle when warm not as noticeable cold start. I suspect a worn valve but I hate to just tear it apart but I'm about to be stumped. I am going to check the harness for wear or damage but I don't suspect that is the problem - maybe for the misfire but not the compresson. I also am going to pull the top of the intake off to see if there is buildup inside but that doesn't point to lower compression. Any ideas?

 

Welcome to DF

I would say you are the right track. I would also say you have a burnt intake valve.

 

Thanks. Been a Dodge guy forever. Like your Viper motor. Hope mine stays in the car not on the stand. Going to get the van back in the shop next week. We'll see what the folks want to do. Lots of miles and not a cheap repair.