Coil on plugs keep burning out

I have an 03 mustang gt and yesterday while I was driving I smelt something burning and my car started running bad. When I got home I checked the codes and it said my #3 COP was bad so I got a new set and I changed all the spark plugs. This morning I went for a drive and seconds after i started up the car it started idling bad and I smelt something burning again. Checked the codes and this time #3 and #7 were bad. I’ve had this car for about a month and it’s been driving fine I took a road trip to see my family and that’s when this started to happen. My leave ends this Sunday and I need to find out the problem and fix it ASAP so I can make the drive back. The car also has been tuned with an SCT X4 tuner so maybe theres something in the tune that’s causing the problem. Anything will help.

Not exactly clear… did you replace all the coils and all the plugs? What brand parts? Generally burning up a coil takes high resistance at the spark plug. The spark then burns its way out.

Is this a 4.6 2 valve motor? Did you clean the spark plug wells and check the coil connections for dirt and corrosion?

Pull plugs and coils off, buy 2 new coils from Ford, 2 new plugs and make sure they are tightened properly and clean when installed. Make sure the connectors are clean, too.

The SCT X4 should not matter (that is what I use) It doesn’t make thre spark more intense.

So I did change all the coils and plugs. The coils are accel coil on plugs and the spark plugs are dense iridium power. It is the 2v motor and when I was changing them I did check the spark plug wells and they looked clean and the connectors are also clean and had no corrosion.

Didn’t we already discuss this exact issue with the same OP, in another thread?

Why, yes, we did!

I’d suggest he remove those Accel coils and throw them in the nearest trash can and replace them with Motorcraft parts. They are, excuse the coarse language, crap!

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Yea we discussed this already but I’m still having trouble with them. Luckily I have a friend at autozone and he’s got me a deal on the motocraft coils. After I installed them with the new spark plugs the #3 coil still burnt out. I checked the gap and even looked at most of the wiring for the coil connector for any kind of shorts and havent found anything I dont have a clue on what to do at this point.

At this point, I’d take it to a mechanic that has an ignition scope and ask him to take a look at the secondary waveforms.


If the driver in the PCM for that ignition coil is shorted or if the ground triggering wire to that coil is shorted to ground the coil will be energized continuously and overheat in about 30 seconds. Did the top of the coil rupture?

You need to do some circuit testing and figure out if the wiring is shorted or the PCM.


It’s the bottom of the coil on plug that keeps rupturing. The car will be on only for a few seconds before the car starts to misfire and then I get the burning smell. After I pull the coil theres always a little hole with a bunch of this black stuff that comes out and hardens.

I think the advice that @Nevada_545 gave is right on the money. There is something wrong within the PCM that is really causing the trouble. Comparing the internal resistance readings between that coils trigger line and a normal one may show there is a problem internally.

I used “ECM repair & return” service before, don’t remember the exact shop, but found it on ebay and they were like in 100 miles from me: shipped ECM to them, they called in 2 days and informed on the test status, I did not need repairs as apparently the failure was in another components, but that $60 or so bought me an assurance ECM is not at fault.
Looks for something like:

The only problem I have is that I’m on leave right now and have to report back to my base on the 9th so im super crunched on time