Spark Plug Condition; Spark Plug Condition - Electrode Gap Bridging; Spark Plug Condition - Scavenger Deposits - Jeep 1987 Wrangler Workshop Manual

EMEIMES
JP1
ENGINE TUNE-UP PROCEDURES
Always use a torque wrench when .installing the
spark plugs. Distortion from overtightening will
change the plug electrode gap. For all engines,
tighten the plugs with 9.5 - 20 N«m ( 7 - 1 5 ft-lbs)
torque.
Spark Plug Condition
Compare the spark plug condition with the
illustrated e x a m p l e s and the following
descriptions.
Spark Plug
Condition - Electrode
Gap Bridging
Electrode gap bridging can result from loose
deposits in the combustion chamber.
LOW MILEAGE PLUGS WITH THIS
CONDITION MAY BE CLEANED.
60770A
Fluffy deposits may accumulate on the plug
electrodes during stop-and-go driving.
When the engine is suddenly operated with a
high torque load, this material can liquefy and
bridge the gap (i.e., short circuit the electrodes).
Spark Plug Condition - Scavenger Deposits
Fuel scavenger deposits may be white or yellow.
LOW MILEAGE PLUGS WITH j k ^ J
THIS CONDITION MAY BE CLEANED.
S E E
I.S.
N
O
T
E
S
60770B
They may appear to be harmful, but this is a
normal a p p e a r a n c e c a u s e d by chemical
additives in certain fuels.
Such additives are designed to change the
chemical nature of deposits and decrease spark
plug misfire tendencies.
Notice that the accumulation of deposits on the
ground (side) electrode and shell area may be
heavy, but the material is easily removed.
Spark plugs with this type of deposit can be
considered normal in condition and can be
cleaned using standard procedures.
B-23