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Q: Plug wire attached to the distributor cap are arcing from the wire to the distributor cap.

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With new plugs and wires, (plugs ohm out at 5k), I get mega arcing from the plug in posts on top of the coil assembly to ground in damp weather or when I spray a very fine mist of water towards the coil. Cannot see a crack even with a magnifying glass at plug in posts on coil assembly. The arcs are about 1/2" long from bottom of wire boots to ground. With just a normal small gap in the plugs, why does the coil top still arc. What happened to the "path of least resistance"? Why doesn't the plug fire instead, or is 5k ohms on a plug enough to make coil charge seek a easier path. The codes came up Po300, 02, and 04 all at once. # 2 and 4 plug in posts are the ones arcing. Just want to make sure I'm not missing something before I get a new coil assembly. Thanks for any input.

My car has 125000 miles.
My car has an automatic transmission.

Hi there. The spark plug wire is arcing for there is a least path of resistance on the distributor cap. There could be a crack in the cap, but most of the time the spark occurs due to lack of connection. Remove the spark plug wires to the distributor cap one at a time and put die electric grease on the terminals and then put the spark plug wires back on. Allow the one hour for the die electric grease to seal up tight. This will prevent the wires from shorting to the distributor cap. Also, remove the distributor cap and check the terminals on the cap and on the rotor. Use sand paper to clean up the corrosion that is present on the parts. Put the distributor cap back on and recheck for any sparking. If the sparking continues, then either the cap has a crack on it or the terminals have too much corrosion causing an arc. If you need further assistance with your distributor cap arcing, then seek out a professional, such as one from Your Mechanic, to help you.

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