Shadow Convertible L4-153 2.5L SOHC (1994)
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
COLD FOULING (CARBON FOULING)
Normal Operation And Cold(Carbon) Fouling
Cold fouling is sometimes referred to as carbon fouling because the deposits that cause cold fouling are basically carbon. A dry, black deposit on
one or two plugs in a set may be caused by sticking valves or misfire conditions. Cold (carbon) fouling of the entire set may be caused by a
