Attach the spark plug to a spark plug tester, then connect the tester to the ignition wire. Start the engine and observe the ...

How to test a spark plug Although this is something you can certainly leave up to the professionals, it’s also simple enough to do at home.

It’s more likely that your spark plugs just haven’t been replaced since 1996, and the ceramic insulation on one of them cracked.

Testing the new Brisk premium spark plug line in a 2003 Cobra, brought to you by 5.0 Mustang & Super Fords Magazine.