Some days it's runs like a plugwire is off,,,

[Wake Bandits]

2007 MP 340 HP.
Anyone experience the same issue?
Some days runs smooth, some days rough.
Any takes?

[mtnsmith]

I remember someone else had a similar problem and found a hairline crack in one of the sparkplugs, I'd pull them all and check.

[chpthril]

If you have a 12v test light, here is an easy way to find a bad plug/wire.

Ground the test light, start engine, now take the tip of the test light and drag it up and down each plug wire, all around the boots at the cap and plugs. If you find a crack in a plug, or a weak spot or cut in a wire, the spark will run to ground through the test light and the engine will skip/miss.

Also a spray bottle of water will help create a path to ground and help locate cracked plugs or bad wires.

[Wake Bandits]

Thanks for the tips.