Cop Question

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Feb 24, 2012 | 07:00 PM

mudder1_2000

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Cop Question

So my 99 Navi decided to start running rough today. Definatly a miss. I believe I have narrowed it down to the #3 cop. I swapped it with the #1 cop and there was no change when I disconnected the connector to the problem cop in either position The wierd thing is when I take the cop off the plug and groung it to the engine there is a spark. (white in color). Should the cop spark at all if it has failed?

Feb 24, 2012 | 07:14 PM

pdqford

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From: Central NYS

Quote:

Originally Posted by mudder1_2000

The wierd thing is when I take the cop off the plug and groung it to the engine there is a spark.

It takes a good amount of voltage to fire a sparkplug when it is in the combustion chamber and under 120+ psi of compression pressure. Out in the free air at atmospheric pressure the voltage to create a spar is much less.

Quote:

Originally Posted by mudder1_2000

Should the cop spark at all if it has failed?

That's gonna depend on how it failed. If it has melted the windings to the point there is no continuity through the primary side, it ain't gonna spark. If its just weak, it may spark when not stressed.

But I look for a nice blue spark and a pretty loud "snap"! Be sure you have full battery voltage at the coil's harness side connector.