Howdy guys. I have a 2003 Town and Country Limited, with a 3.8 Liter. A couple of days ago I replaced the back valve cover gasket, because it was leaking oil. To do this, the upper intake manifold had to be taken off - no big deal. With everything torn off, I thought it was a great time to change out spark plugs, since I just turned 113k miles. Again, obviously no biggee. With the gasket and spark plug swap complete, I reassembled the motor. All wiring pigtails and vacuum lines are correctly fastened. Here is the problem. The engine has a miss when it is idling, and if you accelerate any more than 1/4 throttle, it will backfire to high heaven, and gain no speed or rpm's (generally happens around the 2k-3k RPM mark). Only when actively backfiring would the check engine light flash. So I thought, "Huh...", and I changed plug wires. The van seemed to be fixed, so i thought. But driving it home from the garage at my work(where I did the repair), it started backfiring again, but the CEL stayed on! So I thought "YES!", I'll have this sucker read and then I can properly diagnose this! It read Cylinder 6 misfire (P0306 I think). So I pulled the plug on 6 (front right cylinder, easiest one to get to luckily), and the plug looked brand new! Probably because it is brand new...lol. Then, with the engine running, I pulled the wire boot off of cylinder #6. It had a very weak spark - I pretty much had to touch the boot to the exhaust header to get a spark. I pulled the other two front cylinders, and observed hellacious sparks - it was a neat lightning show. So I put the O.E. wire back on the coil and with the engine running, I observed the same, insignifficant spark. So I thought it must be the coil pack! So I replaced the coil pack and ..... same iddy biddy spark... "Eff!"... This is my transportation for the kiddos, and my pregnant wife. It is tremendously important to get this rig back up and running. I can't be the first person to see or experience this, and I'm begging for a helping hand. Please, take the floor!

 

Welcome to DF
Did you have this problem before you replace the valve cover gaskets? There has been a problem with the wire harness on the rear head. I would open up the harness and inspect the wires.

 

No, sir. I did not have the problem before the gasket/plug swap. What confuses me, is how in the heck does one cylinder get 1/5th the spark to it through a new coil and new plug wire? What would tell a new coil pack to drive an extremely weak spark to one cylinder? It is clear as day, when the engine is running. Pull the boot off of the plug on cylinder 6 and the spark is very weak. Pull the boot off of the other two front cylinders - the spark is very strong. If I were to have damaged the wiring, I would imagine that spark would go away all together, and not just decrease. I called a mopar dealership and they stated that they thought the pcm would need re-flashed. Ever heard of that? Im just not comprehending what would make a coil pack deliver an inadequate spark to one cylinder... The old coil pack was doing that - that is what made me think it was bad. And I've put the OE plug wire on the coil pack and I observe the same, tiny spark. . . . . . ?!?

 

Trace back to what you did, But i think the problem maybe with wire harness going to the coil pack. You may have just moved something and then you now have this problem. Also check for any pinched wires too.

 

xdm , i have same problem with my 02' dodge caravan xcept cylinder #2, replaced coil pack ,got strong spark but still rough idle, did not replace plugs/wires yet? did you resolve your issue? removed plugs 2,4,6 they are black and carboned , did not do back ones yet, spark plug wires are 9.7k, 1 ? had new pcm installed about 6 mos ago.

 

How can you determine you're getting 1/5th the spark? Have you actually measured kV?

 

Maybe map sensor,TPS, O2 sensors or the wire harness on the rear cylinder head. Remove all the plugs and do a compression test. Also do you have any store codes in the PCM.

 

i have, p1684 batt, p0302#2 cyl and evap code p0445,replaced o2 sensor before pcm change?

 

ok, replaced plugs and wires, plugs were really bad, still rough idle but smoothes out when you hit higher rpm, ??? any suggestions ?

 

Is the van still misfiring and giving you a P0302 code?