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 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 wires

2. Check the electrode gap.

Electrode Gap:

- Adjust the gap with a suitable gapping tool.




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

Spark Plugs

'97 - '98 models:
ZFR5F-11 (NGK)
KJ16CR-L11 (DENSO)

'99-00 models:
ZFR6F-11 (NGK)
KJ20CR-L1 1 (DENSO)

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 Nm (1.8 kg.m, 13 lb.ft).