Spark Plug: Testing and Inspection
ON-VEHICLE INSPECTION1. INSPECT SPARK PLUG
NOTE: Do not use a wire brush for cleaning.
a. Check the electrode.
1. Using a megohmmeter,measure the insulation resistance.
If the insulation resistance is the specified range, replace the spark plug.
NOTE: If a megohmmeter is not available, perform the given simple inspection instead.
b. 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.
c. Check the spark plug for any damage on its threads and insulator. If there is any damage,replace the spark plug.
HINT:
Maximum electrode gap for a used spark plug: 1.3 mm (0.0511 in.)
If the gap is greater than the maximum, replace the spark plug.
Electrode gap for a new spark plug: 1.0 to 1.1 mm (0.0394 to 0.0433 in.)
NOTE: Do not adjust the electrode gap of any spark plug,as the ground electrode tip will be damaged.
d. If the electrode has traces of wet carbon,allow it to dry and then clean with a spark plug cleaner.
Standard air pressure: 588 kPa (6.0 kgf/sq.cm, 85 psi)
Standard duration: 20 seconds or less
HINT: Only use the spark plug cleaner when the electrode is free of oil. If the electrode has traces of oil,use gasoline to clean off the oil before using the spark plug cleaner.