Mustang Cobra V8-281 4.6L DOHC VIN V MFI (1997)
Spark Plug: Testing and Inspection
1. Oil Fouled
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Identified by wet black deposits on the insulator shell bore electrodes.
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Caused by excessive oil entering combustion chamber through worn rings and pistons, excessive clearance between valve guides and stems, or
worn or loose bearings. Correct oil problem. Replace the spark plug.
2. Gap Bridged
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Identified by deposit build-up closing gap between electrodes.
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Caused by oil or carbon fouling. Clean the spark plug.
3. Pre-Ignition
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Identified by melted electrodes and possibly blistered insulator. Metallic deposits on insulator indicate engine damage.
