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Discussion Starter · #1 ·
I've got a questing about the ignition coils. If I hook up -12V to the negative side of the coil and momentarily touch +12V to the positive side of the coil will it produce a spark
 

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I've got a questing about the ignition coils. If I hook up -12V to the negative side of the coil and momentarily touch +12V to the positive side of the coil will it produce a spark
No. Only when the negitive connection is broken will it discharge through the plug wire as high voltage to produce a spark. 12V+ is a constant on the coil with the key on and the CDI provides a ground for charging except when it wants it to fire..and that's when it breaks the 12V- or ground connection. The CDI or ECU bases this timing on input from the pulse coil or CPS. You should know two things, 1-left with power on them charged for long periods..and we mean seconds..is hard on coils. And two, if the high voltage discharge has nowhere to go..as in can't jump to ground, it can and will jump internally destroying the coil. So make sure the plug is attached and is laying against the engine case or somewhere it can jump to ground.
 

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Discussion Starter · #3 ·
OK.. What did I do wrong.. I removed one of the ignition coils and put on a bench. I have a car battery and jumper cables.. I hooked the positive side of the jumper cable to the + side of the coil. I put a small metal screwdriver into the spark plug boot and attached a jumper wire from the negative side of the jumper cable to another screwdriver and put the two screwdrivers close together. I then touched the negative jumper cable to the - side of the ignition coil several times to try and see a spark, All of a sudden an extremely loud POP and the ignition coil exploded.
 

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OK.. What did I do wrong.. I removed one of the ignition coils and put on a bench. I have a car battery and jumper cables.. I hooked the positive side of the jumper cable to the + side of the coil. I put a small metal screwdriver into the spark plug boot and attached a jumper wire from the negative side of the jumper cable to another screwdriver and put the two screwdrivers close together. I then touched the negative jumper cable to the - side of the ignition coil several times to try and see a spark, All of a sudden an extremely loud POP and the ignition coil exploded.
That's what happens when it needs to discharge...and can't through the high tension lead. It does it by shorting internally. Even after disconnected if it can't discharge, it will hold that charge like a capacitor...except the voltage is too high to retain for long. In the machine when you shut the key off it still has access to the plug for discharge and does so. Tough lesson to learn.
 
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