Spark Plug Faults

Spark Plug Voltage Peak Evaluation





1 Normal ignition voltage peak. Spark plug is okay.
2 Low ignition voltage peak. Small electrode gap.
3 High ignition voltage peak. Large electrode gap.

Evaluation of Sparking Period at Idling Speed





Normal sparking period. Spark plug is okay.





Long sparking period.
Small Electrode gap.





Short sparking period.
Large electrode gap.