Ignition coil issue
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Ignition coil issue
Hello, I am having the following issue. My number 3 ignition coil keeps getting hot and going out. I have rewired the pig but it keeps popping the coil repeatedly. I've tried different coils and it has even split the coil when it pops (overheats and literally makes a popping noise)It is only the number 3 coil that is doing this. I have an 02 expedition 5.4. Does anyone have an idea what may be causing this issue?
Thanks for any ideas that may help
Thanks for any ideas that may help
Postmaster
Joined: Jun 2014
Posts: 3,206
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From: Oakhust NJ Jersey Shore
Is the spark plug tight? Did you check the plug and make sure your gap is .52-.56? Something is causing the coil to produce lots of juice, never heard of it, maybe someone else can chime in. 
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It is only misfiring after the coil goes bad. I keep replacing the coil and it lasts just a matter of minutes. How do I check the ground on the control wire? I don't know much about wiring but can follow instructions good. I am looking for a wiring diagram, so any info would be greatly appreciated.
Thanks
Thanks
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Logistics Pro
Joined: Jan 2001
Posts: 3,740
Likes: 37
From: Central NYS
The control wire should only be pulled to ground when the PCM wants to energize the coil and when the PCM then releases the ground the coil should throw a spark. (Note: the common colored coil wire is battery power to the coils and the "non-common" colored wire at each coil is the coil's control wire.)
If the control wire has some how found a path to ground without using the PCM's ground, the coil will be continually energized and will get hot. (If that happens while the engine is running you should have a misfire on that cylinder.)
To see if the control wire has a path to ground, with the key off, unplug the harness containing the control wire from the PCM. Also unplug the coil from the harness. Then using your DVM set to ohms, probe the control wire at the coil harness connector with one DVM probe and probe the battery negative post with the other DVM probe. There should be no continuity. If there is continuity, the coil will be continually energized and will not throw a spark when the PCM release the coil's ground (because the coil has found its own ground).
If there is no continuity, then connect the harness to the PCM and run the test again. If there is now continuity, the coil driver within the PCM has shorted to ground.
If the control wire has some how found a path to ground without using the PCM's ground, the coil will be continually energized and will get hot. (If that happens while the engine is running you should have a misfire on that cylinder.)
To see if the control wire has a path to ground, with the key off, unplug the harness containing the control wire from the PCM. Also unplug the coil from the harness. Then using your DVM set to ohms, probe the control wire at the coil harness connector with one DVM probe and probe the battery negative post with the other DVM probe. There should be no continuity. If there is continuity, the coil will be continually energized and will not throw a spark when the PCM release the coil's ground (because the coil has found its own ground).
If there is no continuity, then connect the harness to the PCM and run the test again. If there is now continuity, the coil driver within the PCM has shorted to ground.
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Thanks so much for all your help. I tracked the wire back to the PCM and rewired it direct from pcm to coil pig. So far I have driven about 100 miles today testing it and it is working great. Once again your response really helped me ID and track down the problem!
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