Spark Plug Inspection

Remove the ignition coils and the spark plugs (see IGNITION COIL AND SPARK PLUG REMOVAL/INSTALLATION ).
Inspect the electrodes and the ceramic insulator.
- Burned or worn electrodes may be caused by these conditions:
  - Advanced ignition timing
  - Loose spark plug
  - Plug heat range too hot
  - Insufficient cooling
- Fouled plugs may be caused by these conditions:
- 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
Fig 1: Identifying Incorrect Spark Plug Gap
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Replace the plug at the specified interval, or if the center electrode is rounded (A), or if the spark plug gap (B) is out of specification, or if the spark plug electrode is dirty or contaminated. Use only the spark plugs listed.
NOTE:
- Do not adjust the gap of iridium tip plugs.
- Do not use a plug cleaner.
Fig 2: Identifying Spark Plug Gap
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Install the spark plugs and the ignition coils (see IGNITION COIL AND SPARK PLUG REMOVAL/INSTALLATION ).