How common is a dead spark plug?

[rrichar]

I have been chasing an engine miss. This weekend I found out I had a dead sparks plug. It was not firing at all. Found out because I put my timing light on each wire to see if I had broken a wire connector while putting on my new tall manifolds. There was no physical evidence of anything being wrong. No massive build up, no broken insulator. Put in a new plug and presto, it runs on all cylinders and timing light flashes as it should.

How common is this? I have never heard of it, fouled yes, not working at all never.

[Grady Clay]

Rob,

That isn’t a common issue but I understand exactly what you describe.

This is the reason that everyone chasing some misfire gremlin should start with a new set of sparkplugs. Racers typically have a run-in and tested set as a diagnostic tool.

Good that you found the problem.

Best,
Grady

[James Brown]

it happens, check the resistance from the electrode to the case if it's infinity, there is a open in the plug, if there is a high (greater than 15k), it's too much for the spark to to jump. I do this every time I clean or replace plugs. sometimes, you get a bad one from the factory-it just happens.

[GH85Carrera]

I have to say I have never heard of a plug that just did not work. The good news is that is was a easy & cheap fix. That does not happen often.

[scottb]

I recently had a problem with what felt like low power in the helicopter. The old spark plugs all looked fine, but we replaced them anyway with a new set. The difference was like night and day!

Grady's advice is good -- using a new set of spark plugs provides a baseline, and eliminates the plugs as a potential source of the problem.

[dshepp806]

and not a wallet-breaking event, either.