Grand Cherokee 2WD V8-4.7L VIN N (2000)
Spark Plug: Description and Operation
This engine uses resistor type spark plugs. These engines are equipped with "fired in suppressor seal" type spark plugs using a copper core ground
electrode.
Because of the use of an aluminum cylinder head on this engine, spark plug torque is very critical.
To prevent possible pre-ignition and/or mechanical engine damage, the correct type/heat range/number spark plug must be used.
Plugs on both engines have resistance values ranging from 6,000 to 20,000 ohms (when checked with at least a 1000 volt spark plug tester). Do not use
an ohmmeter to check the resistance values of the spark plugs. Inaccurate readings Will result. Remove the spark plugs and examine them for burned
electrodes and fouled, cracked or broken porcelain insulators. Keep plugs arranged in the order in which they were removed from the engine. A single
plug displaying an abnormal condition indicates that a problem exists in the corresponding cylinder.
Spark plugs that have low mileage may be cleaned and reused if not otherwise defective, carbon or oil fouled. Also refer to Spark Plug Conditions.
CAUTION: Never use a motorized wire wheel brush to clean the spark plugs. Metallic deposits will remain on the spark plug insulator and will cause
plug misfire.
