Spark Plug: Testing and Inspection
ON-VEHICLE INSPECTION1. CHECK SPARK PLUG
a. Remove the ignition coil.
b. Remove the spark plug.
c. Check the electrode.
1. Using a megohmmeter, measure the insulation resistance.
Correct insulation resistance: 10 mohms or higher
HINT: If a megohmmeter is not available, perform the given simple inspection.
d. Alternative inspection method:
1. Quickly accelerate the engine to 4000 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.
e. 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.
f. Clean the spark plugs.
g. Check the spark plug electrode gap.
Maximum electrode gap for used spark plug: 1.3 mm (0.0512 in.)
If the gap is greater than the maximum, replace the spark plug.
Electrode gap for new spark plug: 1.0 to 1.1 mm (0.0394 to 0.0433 in.)