Testing COP's
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Joined: Aug 2007
Posts: 66
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From: Brunswick, Ohio
Testing COP's
A repair manual i have has a section on testing COP's. It says primary resistance should be 0.55 ohms and secondary should be 5,500 ohms. Mine all test almost perfect in my '01 4.6 .Is that an accurate test on the condition of the coils?, or could the coils still be failing under a load even if they test fine on the bench?.
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Joined: Jul 2004
Posts: 6,200
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From: Easton, Pa.
It's not a reliable indication of absolute health.
If a coil has shorted turns, you can't detect it with normal meter checks.
Shorted turns result in lower output and not total failure but can cause stumble under certain conditions.
Been through all this and the conditions to find out that the coils all measure fine but some fail stress testing and was the problem causeing stumble without a CEL lamp or a code set.
If a coil has shorted turns, you can't detect it with normal meter checks.
Shorted turns result in lower output and not total failure but can cause stumble under certain conditions.
Been through all this and the conditions to find out that the coils all measure fine but some fail stress testing and was the problem causeing stumble without a CEL lamp or a code set.