melted COP

[TXEnginerd]

I keyed the ignition on today for the first time since upgrading my fuel system for E85. I was checking my fuel pressure at the regulator when I noticed a burning smell. I knew it had to be electrical since the motor wasn't running. Soon enough I saw white smoke coming out from under the driver's side COP cover. This is what I found underneath (cylinder #8):

I did change my spark plugs since the last time it was turned on but I don't know how that could have led to this. Is this how COPs typically fail or do I need to look for some wiring issue elsewhere?

And does anyone have the motorcraft part number for the dohc cobra OEM replacement? I do not want an aftermarket one.

 

[P Weave]

That's unfortunate :shrug:

The OEM Motorcraft P/N is: 4L7Z12029AB

The only thing I can come up with is that maybe you got water or some other liquid on the top of the spark plug so when you put the coil on top of it that made it short out... or maybe it was simply that coils time and it internally shorted out and fried itself.

It shouldn't matter what fuel or plugs you're running (especially just key on) because the COP doesn't know the difference. If you didn't make any modifications to the coil harnesses everything should work as advertised. I'd pick up an new coil, ebay for around $45, and make sure none of the harness wiring is cut/shorting, the top of the plugs are dry, and try it again!

Good luck!

 

[TXEnginerd]

Well, I took the multimeter to the COP harness wires and found that #8 was hot - 12V and too much current for my meter to read. I went and checked where the main harness connects to the ECU since I had it disconnected to remove my J&S since I'm going E85. I found that COP #8's pin on the ECU (pin #79) was bent! I think it was shorted with pin 80 which is for the FPDM which explains the 12V.

I tried to take the ECU apart to get at the pin from the underside but ran into some epoxied bolts preventing me from taking it completely apart. So I just straightened it out from the outside. I plugged it back in and the #8 COP connector is no longer hot with ignition on. I need a new COP before I can see if it actually runs though. I'm worried I may have disconnected the pin from the circuit board completely and #8 won't get the fire signal from the ECU.

And I found a couple used COPs on ebay for $15 each with free shipping.

 

[TXEnginerd]

I took the ECU back out and apart again. I checked resistance between the harness pin and the soldered joint on the pcb and got 0 ohms . So I think I am good once I get the replacement COP. I was just worried that the pin in the harness was one solid piece that connected to the pcb. So pulling on it would have messed it up but that does not seem to be the case.

Pic for reference:

 

[MalcolmV8]

Man that could have been a real tricky problem to find. Glad you figured that one out.

 

[Swervedriver]

OUCH! But nice work tracking it down so quickly.

 

[P Weave]

I took the ECU back out and apart again. I checked resistance between the harness pin and the soldered joint on the pcb and got 0 ohms . So I think I am good once I get the replacement COP. I was just worried that the pin in the harness was one solid piece that connected to the pcb. So pulling on it would have messed it up but that does not seem to be the case.

Pic for reference:

Thats some good information for future reference. Thanks for sharing and glad you got it figured out! :beer:

 

[jblood37]

Thats some good information for future reference. Thanks for sharing and glad you got it figured out! :beer:

Yep. Subscribed just in case

 

[tuscani66]

If you need a replacement coil, I have my OEM coils still, I can mail you 1 or all of them.

Only replaced them because I got free set (GT500, same though) when buddy upgraded his GT500 and they sent him the wrong coils than said to him that he could keep it. So changed my plugs and put new coils in cause "what the hell" haha. My OE has about 20k on them.

 

[TXEnginerd]

If you need a replacement coil, I have my OEM coils still, I can mail you 1 or all of them.

Only replaced them because I got free set (GT500, same though) when buddy upgraded his GT500 and they sent him the wrong coils than said to him that he could keep it. So changed my plugs and put new coils in cause "what the hell" haha. My OE has about 20k on them.

That's the most annoying part to me - my COPs only have 40k on them and I already killed one. So thank you for the offer. Let me see what kind of shape the used ones I bought on eBay show up in. If they are bad, then I will take you up on it.