Hey guys, ran into a major issue with my wife's 2002 Dodge Grand Caravan eL (3.3l). Last night when we were coming home it developed a severe miss when pulling into the driveway. It drove home without issue but as soon as we pulled into the driveway it started shaking and running rough. Not just at idle, either. With moderate rev the miss did not resolve. I shut the vehicle down as it was late and planned on further troubleshooting today, thinking it was probably a bad or displaced spark plug wire, bad plug, injector issue, etc.
This morning my wife started the vehicle to warm it up and it was still missing. I didn't expect it to resolve after cooling down, but it was still missing. Then it stalled.
I managed to restart it once, it was a hard start and required a little throttle to keep it running once it hit. It did not run more than a few seconds and then stalled again.
I attempted to restart it a few more times, no hit.
I'm now hearing an intermittent buzzing sound from under the hood. I could only localize it to an area to the rear (driver's side) of the motor, near perhaps the ABS pump, the top of the transaxle, etc.
Then it stopped cranking with the key, well before the battery should have been exhausted. A faint click from under the hood is all that I could get with the ignition switch.
The buzzing persists off and on. Usually comes back for a few seconds after an attempt at starting from the ignition. Wiggling various wiring harnesses and banging on the top of the power distribution block *may* interrupt the buzzing, but it is intermittent enough that I cannot say for certain.
I attached jumper cables to another car, battery to battery, no change, still no turn over from key.
With jumper cables attached, battery to battery, I then tried jumping the starter relay. The starter spins the engine over with little to no unusual effort - turn over normal, no start (not expected).
I moved the negative jumper cable to the only nearby engine ground (and I know it's not a good one, gaskets, etc.) at the thermostat housing. No change. No crank from key, turns over (slightly easier/faster) by jumping the starter relay, no start.
I did a brief visual/feel inspection of the wiring harness behind/below the ignition coil. It's crispy. I squeezed the connectors back together but did not do a full disconnect and re-seat on anything (it's really cold and my fingers are about numb at this point). No change, except at some point the buzzing sound coming from the area behind the battery seems to have become less common.
I attempted the key-dance to display fault codes on the odometer. I've done this before for other issues. I was unable to get fault codes to display using this method, however.
I googled a bit and found a few things. Some people mention a recurring issue with this generation of van in that the injector harness may be melted/damaged, and/or the harness going to the coil pack, and one video indicates that the ECM may be faulty as well. I even saw someone had taken a picture of oil leaking out of the ECM which had evidently been pumped up the harness through a leaky pressure sending unit. I believe I have a leaky pressure sending unit, lots of oil on the harness and below, and I get an oil light at idle. The engine is not low on oil, in fact, it's slightly above full. I have had an issue with a fuel smell from the engine for some time now that I believe I have localized to a leaky fuel pressure regulator on the fuel rail. I understand the entire fuel rail must be replaced to fix this, though, so I have put up with it for a while. I'm somewhat concerned that a small fire may have cooked my ignition/injector harness and this may have potentially caused issues in other areas due to short circuits developing in the burned harness.
Here's some of what I've run across in searching for issues which seem to match the symptoms I'm getting: