Catastrophic Coil Issue
02-02-2015, 04:43 PM
#1
Non-Savant Idiot
Thread Starter
Catastrophic Coil Issue
2007 MT RX-8
78,000 mi
Coils, plugs, and wires replaced @ ~60k
So recently I was driving my 8 when the engine started continuously misfiring. I'm fairly familiar with this as that is what began to happen when I last replaced my coils and plugs. I immediately drove to an Autozone to have them check the CEL to confirm my suspicion and maybe point to any other problems that could be going on. Once I arrived I noticed that one of my spark plug wires (leading front) had come loose. I immediately reconnected it and tried to start the car, but at that point the engine had flooded. They read the code and it indicated a cylinder 1 misfire, so I called my dad to come boost me while I deflooded the engine. After we got it running there was still a continuous misfire, so I limped it a few miles back to my house.
Today, while ripping out all of my wires and coils I noticed that the connection to my trailing front coil was completely melted out. I assume this was causing my misfire after reconnecting the loose wire. So my question is: would the loose leading wire have caused an overcurrent flow into the trailing coil that caused the connection to melt or is there some other electrical issue that's been slowly melting it that I need to look into?
I've pulled all the coils, plugs, and wires. The plugs and wires all seem to have normal resistance through them, but the one coil is definitely f***ed.
Pics:
http://i1303.photobucket.com/albums/...psuye7jtus.jpg
http://i1303.photobucket.com/albums/...psnehx7q9r.jpg
78,000 mi
Coils, plugs, and wires replaced @ ~60k
So recently I was driving my 8 when the engine started continuously misfiring. I'm fairly familiar with this as that is what began to happen when I last replaced my coils and plugs. I immediately drove to an Autozone to have them check the CEL to confirm my suspicion and maybe point to any other problems that could be going on. Once I arrived I noticed that one of my spark plug wires (leading front) had come loose. I immediately reconnected it and tried to start the car, but at that point the engine had flooded. They read the code and it indicated a cylinder 1 misfire, so I called my dad to come boost me while I deflooded the engine. After we got it running there was still a continuous misfire, so I limped it a few miles back to my house.
Today, while ripping out all of my wires and coils I noticed that the connection to my trailing front coil was completely melted out. I assume this was causing my misfire after reconnecting the loose wire. So my question is: would the loose leading wire have caused an overcurrent flow into the trailing coil that caused the connection to melt or is there some other electrical issue that's been slowly melting it that I need to look into?
I've pulled all the coils, plugs, and wires. The plugs and wires all seem to have normal resistance through them, but the one coil is definitely f***ed.
Pics:
http://i1303.photobucket.com/albums/...psuye7jtus.jpg
http://i1303.photobucket.com/albums/...psnehx7q9r.jpg
02-03-2015, 08:59 AM
#2
Non-Savant Idiot
Thread Starter
Update: I've been in contact with Charles from BHR. He told me that while it was common for the plug wires to sometimes fall off, he had never seen a melted connector like that. Anyone have any idea what could have caused this?
02-03-2015, 09:11 AM
#3
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It doesn't seem too surprising to me.
When a coil charges up, it builds internal heat. If the coil can't release the charge, that heat can't really disapate.
Charging a coil 300 to 3,000 times per minute but not letting it ever release it's charge is going to be building a lot of heat. A coil plugged into the harness but not into a plug is going to fail rapidly. The fact that the internal heat was enough to melt something isn't really something seems unreasonable or needing of an alternate explanation, especially when they are bolted to an engine that is already putting off enough heat to heat soak most engine bay components to around 250F.
When a coil charges up, it builds internal heat. If the coil can't release the charge, that heat can't really disapate.
Charging a coil 300 to 3,000 times per minute but not letting it ever release it's charge is going to be building a lot of heat. A coil plugged into the harness but not into a plug is going to fail rapidly. The fact that the internal heat was enough to melt something isn't really something seems unreasonable or needing of an alternate explanation, especially when they are bolted to an engine that is already putting off enough heat to heat soak most engine bay components to around 250F.
02-03-2015, 07:58 PM
#4
your coil has failed(usually igniter), created a short, so it melt ur plug
seen it couple of times, usually because coils are seriously due (I still see A coils, hell I even seen the original coils once, Not even A, and it's 2015 now), but in rare cases (B), it just gave up for no reason (less than 10K miles) and burnt itself.
replace the plug, move on. (it's a bitch *** job)
seen it couple of times, usually because coils are seriously due (I still see A coils, hell I even seen the original coils once, Not even A, and it's 2015 now), but in rare cases (B), it just gave up for no reason (less than 10K miles) and burnt itself.
replace the plug, move on. (it's a bitch *** job)
Last edited by nycgps; 02-03-2015 at 08:02 PM.
02-03-2015, 09:59 PM
#5
Non-Savant Idiot
Thread Starter
nycgps: I just replaced the coils a year and a half ago. They don't even have 25k on them yet.
It must have been the loose wire. I did drive it several miles with the wire off the plug. The problem I'm having now is locating a new connector. Or at least a wiring harness cheap enough that I can pull the connector off.
It must have been the loose wire. I did drive it several miles with the wire off the plug. The problem I'm having now is locating a new connector. Or at least a wiring harness cheap enough that I can pull the connector off.
02-04-2015, 08:25 AM
#7
Non-Savant Idiot
Thread Starter
Holy Christ...thank you so much. I've been looking around the web for days trying to find that. You are quite possibly my new favorite person haha
02-09-2015, 11:48 AM
#8
Today, while ripping out all of my wires and coils I noticed that the connection to my trailing front coil was completely melted out. I assume this was causing my misfire after reconnecting the loose wire. So my question is: would the loose leading wire have caused an overcurrent flow into the trailing coil that caused the connection to melt or is there some other electrical issue that's been slowly melting it that I need to look into?
if everything is normal, then the energy required, is fairly small, but if you have a larger gap to jump (a problem), the energy required goes way up.
so if a wire falls off (common with the Rx8), the coil does have to work harder to fire the plug. it does seem to have enough power to do it, but since these coils aren't very robust in the first place, having it do extra work probably means the coil life goes way down.
as for the melting plug, i've seen/heard about a few coils that have a little casting flash, so the plug doesn't seat right = melted coil plugs
02-09-2015, 12:19 PM
#9
Non-Savant Idiot
Thread Starter
way back when i was in school, we put cars on an oscilloscope, and it would show the energy the coil needs to fire the spark plug.
if everything is normal, then the energy required, is fairly small, but if you have a larger gap to jump (a problem), the energy required goes way up.
so if a wire falls off (common with the Rx8), the coil does have to work harder to fire the plug. it does seem to have enough power to do it, but since these coils aren't very robust in the first place, having it do extra work probably means the coil life goes way down.
as for the melting plug, i've seen/heard about a few coils that have a little casting flash, so the plug doesn't seat right = melted coil plugs
if everything is normal, then the energy required, is fairly small, but if you have a larger gap to jump (a problem), the energy required goes way up.
so if a wire falls off (common with the Rx8), the coil does have to work harder to fire the plug. it does seem to have enough power to do it, but since these coils aren't very robust in the first place, having it do extra work probably means the coil life goes way down.
as for the melting plug, i've seen/heard about a few coils that have a little casting flash, so the plug doesn't seat right = melted coil plugs
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