[SOLVED] Smoked coil packs

ajkulish

ajkulish

Greenie N00B Member
Greenie Member
So this one has me a little confused. Just got my speed6 out this year early this month, had been working on getting an aftermarket fan controller hooked up. Got that wrapped up and she had been good for a few days. Probably put 300 miles on the car, between a short weekend trip and a couple commutes to work. No problems at all, car ran as good as I recall in recent times.

Last week, I was pulling out of a driveway onto a main road, I gassed it a little bit through first and second, but not banging gears or anything like that. Just out for a little cruise. Half mile later, just rolling at 35mph, car starts sputtering as if it somehow blew a coupler or something. So I pulled off and took a look, no coupler blown, just smoking coil packs. I run back to shut it off but by the time I get to the key it turns itself off. Towed it a mile back home and getting into diagnosis today.

I have a wiring diagram and have been chasing this down with my dad all morning. Have fried 3 ignition fuses (interior) today just trying to diagnose. Car not cranked, it's like the ECU is sending signal to fire constantly. Fried the adjacent coil pack to the one I noticed initially. Fuse blows before I get a chance to melt 1 and 2. Cyl 3 and 4 coils nice and hot.

Im just trying to think about what could have changed, what one slight acceleration event could have set into play. But feeling a little baffled on this one. Is my ECU smoked too by chance?

Any thoughts appreciated.
 
When I was rebuilding my first 6, I very carefully checked the engine main wiring loom from frame rail (next to fuse block) that area gets a lot of flexing, battery acid, water. I do this on all first engine rebuild projects. PXL_20220814_191024614.jpg PXL_20220814_191054517.jpg PXL_20220814_190248868.jpg PXL_20220814_193210047.jpg PXL_20220814_190248868~2.jpg PXL_20220814_191058470.jpg PXL_20220814_190125711.jpg PXL_20220814_190629523.jpg PXL_20220814_193220350.jpg Found a few discolored wires and they easily bent at the spot if corrosion. A thankless job but when you have electrical issues the basics are easier to do first. The wiring loom in these are now old and exposure to the elements are harsh. Wiring faults can be nonspecific in results. So checking wiring first helps.
 
I bought a speed 6 about 2 years go with the same symptom u are describing - in my case it turned out to be a bad fuel pump resistor - I bypassed it and no more burning coil packs or blowing ignition fuses.
 
Some very interesting suggestions in here! I will start interrogating my harness some more. Luckily I was smart enough when tearing down the last car to keep some spare harnesses. Might just try swapping right off the bat and then work backwards.

The fuel pump resistor is fairly confusing as a solution, but certainly worth looking into!

From my own trouble shooting, I found that cylinders 1 and 2 did not smoke the coil packs, but that cylinders 3 and 4 did, when the vehicle was in the on position (not cranked) and the ignition fuse was in tact. Long enough exposure to this (5 or more seconds) would fry the ignition fuse. There should have been no signal to the coil packs to fire during this exercise. I replaced the ignition fuse, and moved the coils from cyl 1 and 2 to positions 3 and 4, removing the fried coils from 3 and 4 and setting aside. No coils in cyl 1 or 2. Key in on position, or even bumped to crank, these coils did not smoke the same way the previous 2 did. Hoping it is a simple coil issue, but expecting to fry 4 more.
 
Wiring diagram for coils is a simple circuit. Remember the coil output is controlled in one leg directly by PCM. A PCM outputs failure would mean replacement. So care testing. Not sure if safest attempt at trouble shooting is buy 4 new coils.PXL_20230725_235027530.jpg I would look for wiring faults by checking individual wiring in this area.
Wiring manual is in Metal Member area...
Priceless if you ask me.
 
Hey i’m having basically the same issue, 07 Speed 3, Was driving and the car started bogging like a coupler came off but then the coils 3 & 4 would smoke when you turn the ignition on and i’ve replaced the harness and all coils and still smokes when you turn the ignition on. Could anyone possibly lead me in the right direction
 
Dallasppp said:
Hey i’m having basically the same issue, 07 Speed 3, Was driving and the car started bogging like a coupler came off but then the coils 3 & 4 would smoke when you turn the ignition on and i’ve replaced the harness and all coils and still smokes when you turn the ignition on. Could anyone possibly lead me in the right direction
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This is how he fixed it:

ajkulish said:
Following up to this thread. I ended up getting 4 new coils and replacing my coil harness with a spare I took off my last donor motor. This solved my problem. I was able to identify a bare wire inside the harness that I believe was my culprit. Thanks to all for their help.
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