How to diagnose a bad coil?

[bhiland]

Originally Posted by ford3

here is my non scientific way of finding a bad coil, if you cant keep your hand on it after the engine dies because its to hot to handle, its bad

Agreed.

[BRENT in 10-uh-C]

Originally Posted by bhiland

Agreed.

The coil I showed in that link above that I was testing is a coil however it won't get warm at all (much less hot). It even throws a blue spark ...just not very far, -and not very well under an extreme load causing the engine to skip and not produce all the power it was capable of.

So, why doesn't the "hand test" pick up on this substandard coil? One other question, if the hand test is/was accurate, then why were so many coil testers sold??

What I learned is there are quite a few poor to "just OK" coils out there. Once you find a good one, they make a world of difference.

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