- 1 - the normal maximum value of the breakdown voltage, the candle is working;
- 2 - low amplitude of the maximum value of the breakdown voltage, a small spark gap between the electrodes;
- 3 - high amplitude of the maximum value of the breakdown voltage, large spark gap between the electrodes.
Analysis of the spark duration curve at idle speed:
- normal spark duration (pic. 3.49,a), the spark plug is good.
- long spark duration (pic. 3.49b), small gap between spark plug electrodes.
- reduced spark duration (pic. 3.49, in), large gap between the electrodes of the spark plug.