Spark Plug: Testing and Inspection
ON-VEHICLE INSPECTIONINSPECT 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.
- Visually check the spark plug.
If the electrode is dry... Okay.
If the electrode is wet... Proceed to step (d).
- Reinstall the spark plug.
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
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 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.