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Old 01-13-2019, 03:22 PM
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Cool How to test my coil to see if it's any good?

Testing for spark from the coil, I pull the coil wire off the dist cap and turn the car over. Sometimes there is a spark and sometimes not. Does the coil wire terminal need to be close to another piece of metal to see the spark jump or can you see it just by looking into the boot?

I'm thinking my coil may be toast. It's an original '89 Ford piece. How do you test the coil for proper operation?? I have a DVOM.

The coil in question...……………..


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Old 01-13-2019, 05:10 PM
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the coil wire needs to be about 1/4 to 1/2 inch from a ground like the block

the ignition module likely also needs a good ground through the bolts loading it down, but verify with your wiring schematic
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Old 01-13-2019, 05:29 PM
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Unless you're just testing a no start or misfire condition - you should just replace the coil and be done with it.
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Old 01-13-2019, 07:04 PM
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Quote:
Originally Posted by lmsport View Post
the coil wire needs to be about 1/4 to 1/2 inch from a ground like the block

the ignition module likely also needs a good ground through the bolts loading it down, but verify with your wiring schematic
The terminal is sunk a full 1" inside the terminal boot. Ign module is grounded through a factory heat sink.

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Originally Posted by chasracer View Post
Unless you're just testing a no start or misfire condition - you should just replace the coil and be done with it.
I have a strange 'no start' condition. After sitting for 8 hours, the car starts right up and runs fine. Once I shut it off, it won't start again. No spark at the plug wires (terminal 1/2" from plug tip). All plug wires ohmed out good. Replaced rotor and cap. Coil wire ohmed out good. Next would be the coil.
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Old 01-13-2019, 07:30 PM
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Sounds like an overheating situation where the winding in the coil is expanding, breaking connection - no start. After a period of cooling down time, the connection is good again and it starts.
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Old 01-13-2019, 10:20 PM
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Quote:
Originally Posted by chasracer View Post
Sounds like an overheating situation where the winding in the coil is expanding, breaking connection - no start. After a period of cooling down time, the connection is good again and it starts.
Sounds feasible. Is there any way to test it with a multimeter?
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