Spark Plug: Testing and 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 plugs 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. D16Y5, D16Y7, D16Y8 engine:
- Adjust the gap with a suitable gapping tool, and replace the plug if the center electrode is rounded as shown.




3. B16A2 engine:
- Do not adjust the gap of a platinum tip plug: replace the spark plug if the center electrode is rounded or if the gap is not within the specifications.






NOTE: Use only the spark plugs listed.

4. Apply a small quantity of anti-seize compound to the plug threads, and screw the plugs into the cylinder head finger-tight. Then torque them to 18 N.m (1.8 kg.m, 13 lb.ft).