Grand Cherokee 2WD L6-4.0L VIN S (1997)
Spark Plug: Testing and Inspection
Broken, Cracked or Chipped Insulator
ELECTRODE INSULATOR
Chipped Electrode Insulator
Electrode Insulator
A chipped electrode insulator usually results from bending the center electrode while adjusting the spark plug electrode gap. Under certain
conditions, severe detonation also can separate the insulator from the center electrode. A sudden rise in tip temperature or severe operating
conditions are also possible causes. Spark plugs with chipped electrode insulators must be replaced.
Brown to Gray/Tan Color - Normal Operating Condition
DESCRIPTION:
Brown to greyish-tan deposits and slight electrode wear.
POSSIBLE CAUSE
ACTION
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Normal wear
^ Clean, regap, and install, if wear is not excessive
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Dry, Fluffy Black Deposits - Cold or Carbon Fouling
Normal Operation And Carbon Fouling
Symptoms: Dry, black deposits on the electrodes.
Possible Causes:
-
On one or two plugs, may be caused by sticking valves or defective spark plug cables.
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On the entire set, may be caused by a clogged air cleaner.
