[aficio]

2006 Dodge Grand Caravan 151K. A few years ago I lost the coil, only the number one was not putting out anything.
so I changed the coil. A couple of years later the same thing happened, only number one. So I Changed the coil again. Six months later the same thing. So I changed it again two weeks later the same thing. So I start thinking it just did not burn in well. So I replaced another, two day's latter it is gone. So I study a little and get a new ECM with a new coil. Two days later same problem.
So off to the mechanic, it goes. My normal guy call's me a say's up front, to take it to an auto electric repair. We take it there, and I had asked while they were working on it to put in a new set of plugs and wires. Once they got to it. They tell me it is fixed and it was the plug wire that was the problem and that they changed the plugs and wires and put in the new coil and it should be fine.
Two days later, you guessed it, it is starting to act up like before. I have not lost the number one yet, but once the engine has been in operation for 20 or 30 minutes that same sublet miss seems to be coming back.
I have no clue at this moment as to what could be causing it.

I know years ago I had a car that would just basically start running so rough you would need to pull to the side of the road and let it cool down. I eventually walked down a wiring harness to find two wire partially melted together.
so when it got hot, they would crosstalk. Once I pulled them apart and moved the harness, I never had a problem again. But with my van, I am lost.

So ECM has been replaced with new coil, plugs, and wires. The same and only coil output is going bad again.

Has anyone seen this?

 

[marvinstockman]

Bad engine ground?

 

[Carbuff2]

X2 on checking the ground (right side engine mount...that clipped-on braided cable).


Make sure the spark plug wire in question cannot not arc to any metal. (At least a half-inch air gap)

I remember seeing a picture here of a plug wire arcing to the dipstick. 04AnniversaryEdition I think...

 

[atoman]

If it's not abrasion on the plug wires from that coil, it's likely heat..

Not entirely sure what you're calling #1 coil, but how hot does it get near the coil?
Is the exhaust pipe heat shield still there and intact?
Have you checked to verify both radiator fans are working?

 

[LEVY]

I don't know what you meant by plug wire. The problem can be the coil connector. If haven't been replaced, replace it.

They tell me it is fixed and it was the plug wire that was the problem and that they changed the plugs and wires and put in the new coil and it should be fine.

 

[aficio]

The vehicle has always been an AZ desert vehicle. So build up of any kind does not really happen to contacts around here. Since the coil works using switching and the same inputs control the other side. Do you have a thought as the what is electrically happening to the number one side to kill it every time but still allow its counterpart to perform as it relates to possible bad contacts?
Thank you

 

[atoman]

Assuming we're talking about 6-cyl 3.3/3.8 (since not stated explicitly), the coil pack contains just 3 coils. The output for #1 cyl. is on the same waste spark circuit as #4 cyl. If #1 output fails while #4 continues to operate normally, the only way this can occur is if #1 output is shorted to ground (bypassing the plug).

Why #1? - it is the closest output to the coil input connector so the distance a spark has to jump to get to ground is probably the least of the 6 outputs. The coil for #1/#4 is also in the middle of the pack and has less surface area to cool down.

Why does the coil fail, repeatedly and in the same manner? Either all of these coils come from the same 'bad' batch (with similar / identical defects) or an external condition is causing the coil packs to fail...

 

[FabricGATOR]

Is it possible that an injector is the problem? It is odd that the #4 cylinder is firing off of that "bad" coil but #1 is not.

They days of me rebuilding the ole QuadraJunk carburetors is soon becoming a past time.
At last count I have over fifty top feed fuel injectors that may be subject to operational faults and / or performance deterioration.
I just installed a set that I had sent out for service and I couldn't be happier.

 

[Carbuff2]

Is it possible that an injector is the problem? It is odd that the #4 cylinder is firing off of that "bad" coil but #1 is not.

Good point...yes perhaps a marginal injector will only cause an issue when the ignition system is weak.

The OP can swap injectors cylinder-to-cylinder to see if the symptom 'moves'.

 

[BillGrissom]

When I had a miss in my 2002 3.8L, I clamped an old-style timing-lamp over each spark plug wire and found the front coil was bad (#1 & #4? cylinders) since "no flashing". I could even hear clicking inside the coil-pack. Thought that was clever, then recently saw that trick on TV (MotorWeek?). I figured it failed because that coil is closest to the engine, thus gets hotter. If a spark wire grounds, that wouldn't hurt the coil-pack, indeed it would like that since easier than jumping the spark gap. A broken spark wire could hurt the coil-pack, since the magnetic energy will find a path to spark to ground, if even thru the primary circuit (could also damage PCM). The 2.4L coil-pack mounts on the valve cover and has a honeycomb aluminum insulator to block heat, which suggests too much heat could damage it. The 3.3./3.8L coil-pack mounts on a steel tray hanging in the air. With normal air-flow, that presumably gave sufficient cooling. Perhaps one of your radiator fans is not turning on when it should, to build excessive under-hood temperatures.

 

[FabricGATOR]

Along the lines that BillGrissom stated above, I heard something neat that I had not considered...

I read somewhere, and most likely on here, around that time I acquired mom's van from her estate. I changed the spark plugs trying to smooth out the idle and stumble. I found the front three plugs were fine but the rear three were gapped a nickle. (you could use a nickle to measure the worn sparkplug air gap).

It was commented that when the sparkplugs are worn out that much, that it is extra work for the coil and noise suppresion ignition wires to carry that arc, that the ignition wires had likely (if only corona) been passing some energy through the insulation, and that it was prudent to change those ignition wires just based on the condition of the spark plugs.

I get it, I believe it now, and in all my years, I had not had that thought ever proposed in such a way.
In fact, it was such a brilliant concept, that I doubt I heard it here...:lol:

 

[atoman]

Are there any secret facilities or aliens in AZ..?

I once saw a car, in which the coil would "fail" every few weeks - it was also mounted over the engine and rodents liked the warmth of the engine to munch on their food and do their business (directly on the connector)... In that case, the connector had to be disassembled and cleaned, the coil itself was fine.