Spark Plug: Testing and Inspection

INSPECT SPARK PLUGS

NOTE:
- Never use a wire brush for cleaning.
- Never attempt to adjust the electrode gap on used spark plug.
- Spark plug should be replaced every 100,000 (60,000 miles).

a. Remove the ignition coil with igniters.




b. Check the electrode.
Using a megger (insulation resistance meter), measure the insulation resistance.
Correct insulation resistance:
10 MOhm or more
If the resistance is less than specified, proceed to step (d).

HINT: If a megger is not available, the following simple method of inspection provides fairly accurate results.




Simple Method:
- Quickly race the engine to 4,000 rpm 5 times.
- Remove the spark plug. (See step (c))
- Visually check the spark plug. If the electrode is dry ... Okay.
If the electrode is wet... Proceed to step (d).
- Reinstall the spark plug. (See step (g))




c. Using a 16 mm plug wrench, remove the spark plugs.




d. Check the spark plug for thread damage and insulator damage.
If abnormal, replace the spark plug.




Recommended spark plug:




e. Check the spark plug electrode gap.
Maximum electrode gap for used spark plug:
1.2 mm (0.047 in.)
If the gap is greater than maximum, replace the spark plug.
Correct electrode gap for new spark plug:
1.1 mm (0.043 in.)

NOTE: If adjusting the gap of a new spark plug, bend only the base of the ground electrode. Do not touch the tip. Never attempt to adjust the gap on a used plug.




f. Clean the spark plugs.
If the electrode has traces of wet carbon, allow it to dry and to clean with a spark plug cleaner.
Air pressure:
Below 588 kPa (6 kg/sq.cm, 85 psi)
Duration:
20 seconds or less

HINT: If there are traces of oil, remove it with gasoline before using the spark plug cleaner.

g. Using a 16 mm plug wrench, install the spark plugs.
Torque: 17.5 Nm (180 kg.cm, 13 ft.lb)
h. Reinstall the ignition coil with igniters.