Spark Plug: Testing and 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 144,000 km (90,000 miles).

a. Remove the ignition coils.

b. Check the electrode.




Using a megger (insulation resistance meter), measure the insulation resistance.

Correct insulation resistance:
10 MOhms 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:
DENSO made SK20R11
NGK made IFR6A11




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 then 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 coils.