Spark Plug: Testing and Inspection

ON-VEHICLE INSPECTION

NOTE: "Cold" and "Hot" in these sentences express the temperature of the coils themselves. "Cold" is from -10 °C (14 °F) to 50 °C (122 °F) and "Hot" is from 50 °C (122 °F) to 100 °C (212 °F).

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 200,000 km (120,000 miles).

a. Remove the ignition coils.







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 ... OK.
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.

Recommended Spark Plug:

If abnormal, replace the spark plug.




e. Check the spark plug electrode gap.

Maximum electrode gap for used spark plug: 1.3 mm (0.051 in.)

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

Correct electrode gap for new spark plug: 1.0 - 1.1 mm (0.039 - 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 then clean with a spark plug cleaner.

Air pressure: Below 588 kPa (6 kgf/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: 19 N.m (194 kgf.cm, 14 ft.lbf)

h. Reinstall the ignition coils.