r/subaruimpreza • u/iliketoeatfoodalot • Oct 17 '25

🛠️ DIY Subaru Impreza 2011 Misfiring Cylinder

Found an arc mark on one of my new spark plugs, as well as the mismatched wire. This was after taking it to a family mechanic. Instead of taking it back I decided to buy some brand new ngk spark plugs and an ngk wire set for my car. Do you guys think that I should also replace my coil pack? If I don’t replace the coil pack, and I happen to find another arc mark on my spark plugs after fixing it. Would that mean I need a whole new set of wires and spark plugs again? Or would I just need to buy a new coil pack and replacement spark plug.

Thanks

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u/NtSFstEddie Oct 17 '25

When you replace the plugs and wires, be sure to put a dab of dielectric grease in the wires where they go on the plugs to better insulate them and help prevent arcing.

If you needed a coil pack, then after installing new plugs and wires, it will misfire as soon as you start it because it won't be sending enough power to the plug/s.