Spark Plug: Testing and Inspection

INSPECT SPARK PLUGS

NOTICE:
^ 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 km (60,000 miles).

(a) Remove the ignition coils (with igniter).

(b) Check the electrode.
^ Using a megger (insulation resistance meter), measure the insulation resistance.

Correct insulation resistance: 10 M Ohms 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 ..... OK.
If the electrode is wet... Proceed to step (d).
^ Reinstall the spark plug. (See step (g))

(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.)

NOTICE: 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: 17.5 N.m (180 kgf.cm, 13 ft. lbf)

(h) Reinstall the ignition coils (with igniter).