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.