Spark Plug: Testing and Inspection

Spark Plug Inspection:

1. Inspect the electrodes and ceramic insulator for:

Burned or worn electrodes may be caused by:
^ Advanced ignition timing
^ Loose spark plug
^ Plug heat range too low
^ Insufficient cooling

Fouled plug may be caused by:
^ Retarded ignition timing
^ Oil in combustion chamber
^ Incorrect spark plug gap
^ Plug heat range too high
^ Excessive idling/low speed running
^ Clogged air cleaner element
^ Deteriorated ignition coil or ignition wires





2. Adjust the gap with a suitable gapping tool.





3. Replace the plug if the center electrode is rounded as shown above.

NOTE: Do not use spark plugs other than recommended types. These plugs are a new type (ISO standard).

4. Screw the plugs into the cylinder head finger tight, then torque them to 18 N-m (1.8 kg-m, 13 lb-ft).

NOTE: Apply a small quantity of anti-seize compound to the plug threads before installing.