Spark Plug: Testing and Inspection
ON-VEHICLE INSPECTIONNOTE: "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 100,000 km (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 MOhm 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.
Recommended Spark Plug:
d. Check the spark plug for thread damage and insulator damage.
If abnormal, replace the 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: 1.0 - 1.1 mm (0.039 - 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 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 coil with igniters.