James A. TenCate writes:
>What exactly goes bad in a coil?
Unfortunately, a coil can fail in enough ways to make it difficult to
troubleshoot easily without substitution of a new, working coil. I've seen
coils fail in 4 ways (with a brief description of each symptom): The primary
or secondary windings opening up (dead coil); overheating of the coil causing
many of the secondary windings to short together (weak spark); break down of
the high voltage secondary insulation (weak or no spark); and cracks or carbon
tracking of the phenolic "tower" where the secondary coil lead attaches
(arcing and mis-firing).
The first one can be measured with an ohm meter, the last one can usually be
caught visually, especially in the dark, but the middle two are very difficult
to measure.
Pat Vilbrandt John Fluke Mfg. Co., Inc. Everett, Washington USA
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