Spark Plug: Testing and Inspection

ON-VEHICLE INSPECTION

CHECK SPARK PLUG

NOTE:
- Never use a wire brush for cleaning.
- Never attempt to adjust the electrode gap on a used spark plug.
- The spark plug should be replaced every 200,000 km (120,000 miles).

a. Remove the engine cover.
b. Remove the air cleaner.
c. Remove the ignition coil.
d. Remove the spark plug.
e. Check the electrode.




1. Using an ohmmeter, measure the insulation resistance.

Correct insulation resistance: 10 MOhms or more

If the resistance is below the specified range, remove the spark plug.

HINT: If an ohmmeter is not available, perform the following simple inspection.




f. Alternative inspection method:
1. Quickly accelerate the engine to 4,000 rpm 5 times.
2. Remove the spark plug.
3. Visually check the spark plug.
If the electrode is dry, the spark plug is functioning properly. If the electrode is damp, proceed to the next step.




g. Check the spark plug for any damage on its threads and insulator.
If there is damage, replace the spark plug. If not, reinstall the spark plug.




h. Check the spark plug electrode gap.

Standard electrode gap: 1.0 to 1.1 mm (0.039 to 0.043 in.)

If the electrode gap is larger than the standard, replace the spark plug.