Spark Plug: Testing and Inspection

INSPECT SPARK PLUG

NOTE:
- Do not use a wire brush for cleaning.
- Do not attempt to adjust the electrode gap of a used spark plug.




a. Check the electrode.
Using a megaohmmeter, measure the insulation resistance.

Correct insulation resistance: 10 M Ohms or higher If the resistance is less than the specified value, proceed to step (e).

HINT: If a megaohmmeter is not available, perform the following simple inspection instead.




b. Alternative inspection method:
1. Quickly accelerate the engine to 4,000 rpm 5 times.
2. Remove the spark plugs.
3. Visually check the spark Plugs.

- If the electrode is dry, the spark plug is functioning.
Reinstall the spark plug.
- If the electrode is damp, proceed to steps (c), (d) and (e).




c. Check the spark plug for any damage to its thread and insulator.

If there is damage, replace the spark plug. If not, reinstall the spark plug.

CAUTION: Please use long-reach plug.




d. Clean the spark plugs.
If the electrode has traces of wet carbon, clean the electrode with a spark plug cleaner and then dry it.

Air pressure: 588 kPa (6 kgf.sq.cm, 85 psi)
Duration: 20 seconds or less

HINT: Only use the spark plug cleaner when the electrode is free of oil. If the electrode has traces of oil, use gasoline to clean off the oil before using the spark plug cleaner.




e. Check the spark plug electrode gap.

Electrode gap: 1.0 to 1.1 mm (0.039 to 0.043 in.)
Maximum electrode gap: 1.4 mm (0.055 in.)

If the gap is greater than the maximum, replace the spark plug.