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.

a. Remove the air cleaner assembly.
b. Remove the ignition coils.
c. 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 the specified value, 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 (d)).
- Visually check the spark plug.
If the electrode is dry ... OK.
If the electrode is wet... Proceed to step (g).
- Reinstall the spark plug (See step (h)).




d. Using a 16 mm plug wrench, remove the spark plugs.
e. Check the spark plug for thread damage and insulator damage.




If abnormal, replace the spark plug.

Recommended spark plug:




f. Check the spark plug electrode gap.

Maximum electrode gap for used spark plug: 1.3 mm (0.047 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: when 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.




g. Clean the spark plugs.
If the electrode has traces of wet carbon, make it dry and then clean it 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, wipe them off with gasoline before using the spark plug cleaner.

h. Using a 16 mm plug wrench, install the spark plugs.

Torque: 19 N.m (195 kg.cm, 15 ft.lb)

i. Reinstall the ignition coils.
j. Reinstall the air cleaner assembly.