1. K20Z2 engine Inspect the electrodes and ceramic insulator. Burned or worn electrodes may be caused by:
   - | Advanced ignition timing
   - | Loose spark plug
   - | Plug heat range too hot
   - | Insufficient cooling
   Fouled plug may be caused by:
   - | Retarded ignition timing
   - | Oil in combustion chamber
   - | Incorrect spark plug gap
   - | Plug heat range too cold
   - | Excessive idling/low speed running
   - | Clogged air cleaner element
   - | Deteriorated ignition coils