The spark plug affects entire engine performance and therefore its inspection is very important.
Check electrode and insulator for presence of cracks, and replace if any.
Sooty Spark Plugs: Much deposit of carbon or oil on the electrode and insulator of spark plug reduces the engine performance. Possible causes:
Burning Electrodes: This fault is characterized by scorched or heavily oxidized electrode or blistered insulator nose. Possible causes:
Measuring Insulation Resistance:
Measure insulation resistance using a 500 volt megaohm meter.
Clean spark plugs with a spark plug cleaner, then adjust the gap:
Raise the ground electrode to an angle of 45 to 60 degrees. If electrode is wet, dry it before cleaning.
Removal & Installation
- Disconnect the negative battery cable.
- Remove the ignition coil(s), as outlined later in this section.
- Use a spark plug socket to remove the spark plugs.
- Inspect the spark plugs, as outlined earlier in this section.
- Install the spark plug and tighten to 13 ft. lbs. (18 Nm). Do NOT overtighten!
- Install the ignition coil(s).
- Connect the negative battery cable.