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 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. Check the electrode gap.
- Adjust the gap with a suitable gapping tool.




Electrode Gap

- Replace the plug if the center electrode is rounded as shown below:

Spark Plugs
BKR5E-N11 (NGK)
K16PR-L11 (Nippondenso)

3. 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 kgf.m, 13 lbf.ft).