Spark Plug: Testing and Inspection

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(60,000 miles).

(a) Remove the ignition coil with igniters.
(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 dry ... Okay.
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/cm sq., 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 coil with igniters.