I am a new dodge owner (new to me). 2003 ram van 2500 with a 3.9l v6. I have learned a lot from different sights about this motor, but I have not learned enough. I recently experienced a misfire #2 code. I have changed the plugs and wires, cap, and rotor. Went with the autolite plugs, borg warner wires. I have followed the tsb routing proceedures for the wires and rerouting of the coil wire. I just completed the intake manifold and pan gasket proceedures for the oil ingestion issue although I had never noticed any usage (not owned very long) The plenum pan had some oil residue on it but did not look as bad as some I have seen. I changed it due to a vacuum pressure test failing. Fuel pressure was at 45psi, spark seems good. I swapped around injectors just for the hell of it. It seemed to run well for about 15 miles after the pan gasket / manifold gasket replacement. I also flushed and refilled the coolant system at this time, and changed the thermostat. I have not changed the cam position sensor or the coil. It is my understanding that the coil would effect more than one cylinder? When I first purchased it I had a fault code for emissions, but took it to ammco to check it and they found a bad hose somewhere? Sorry, not sure what it was, seemed harmless enough at the time, info dumped. I also cleaned the fuel system by pouring sea foam in the throttle body, about 1/2 pint and let sit, ran the smoke out and repeated a little later. I do see some clear oily residue in the plenum pan through the butterfly, but assume its residue from the sea foam. It is clear. I went ahead and did a pretty solid shake down of the wiring harness to see if maybe it was a short somewhere but it did not seem to change the way it was running. In the short period it did run better after the manifold and plenum pan gasket change it seemed to have much more power. Also, is it normal to have some vacuum pressure on the breather tube whan removed from the air cleaner assy? Any help would be much appreciated, Sorry, the compession was checked on that cylinder by aamco and it was said to be good, I believe 160. Sorry if I have confused anyone other than myself with all this. John

 

Is it a solid misfire or an intermittent one? Does it happen at idle, around town, highway, acceleration, steady cruising?

Did you change the cap and rotor with the brass or gold plates ones, or just the cheap aluminum contact ones?

Pull the engine cover off and run the engine at night. In the dark it is a lot easier to see if there is any spark leakage or jumping to ground anywhere.

 

It seems to me to be a solid misfire. No spark leakage noted running in the dark, and the cap has the aluminum contacts. The previous one did as well and the issue is fairly new. Have you had trouble with the aluminum ones? Thanks, John

 

I don't really notice the miss at speed exactly, but powerloss is noticeable

 

Yes I have and many others here will tell you the same thing. The aluminum ones corrode and weaken the spark.

Did you have the skipping before you changed all the parts you listed or after?

 

yes, this is the reason for the work performed so far, at least most of it.

 

Never, never, never use the cheap-o cap-n-rotor aluminum set. You are only asking for trouble. Spend the extra $5 and get the copper/brass type. The aluminum goes soft under friction and heat conditions. Corrosion is another bad element for this material under the hood.

You might get a P0300 or P030X number OBD code using the aluminum cap-n-rotor set. Those OBD codes tell you what cylinder is mis-firing.

 

Then I suspect you're looking at either a cracked head, or a problem with the flex-plate/flywheel assembly.