Oscilloscope Patterns and Waveforms

MEASUREMENT METHOD
1. Clamp the spark plug cable (Number 1 or 3) with the secondary pickup.

NOTE: Because of the two-cylinder simultaneous ignition system, the waves for two cylinders in each group appear during wave observation. However, wave observation is carried out for the cylinder (Number 1 or 3) with the spark plug cable which has been clamped by the secondary pickup.

NOTE: Identification of which cylinder wave pattern is displayed can be difficult, but the wave pattern of the cylinder which is clamped by the secondary pickup will be stable, so this can be used as a reference.

2. Clamp the spark plug cable (Number 1 or 3) with the trigger pickup.

NOTE: Clamp the same spark plug cable as the one which has been clamped by the secondary pickup.

Standard Wavepattern (Part 1):

Standard Wavepattern (Part 2):

WAVEFORM OBSERVATION POINTS

NOTE: Abnormal waveform examples are shown subsequently




Point A:
The height, length and slope of the spark line (refer to abnormal waveform examples 1, 2, 3 and 4) show the following trends.




Point B:
Number of vibrations in reduction vibration section (Refer to Abnormal Waveform Example 5)




Point C:
Number of vibrations at beginning of dwell section (Refer to Abnormal Waveform Example 5)




Point D:
Ignition voltage height (distribution per each cylinder) shows the following trends.

ABNORMAL WAVEFORMS EXAMPLES




Example 1
- Wave characteristics
Spark line is high and short.
- Cause of problem
Spark plug gap is too large.




Example 2
- Wave characteristics
Spark line is low and long, and is sloping. Also, the second half of the spark line is distorted. This could be a result of misfiring.
- Cause of problem
Spark plug gap is too small.




Example 3
- Wave characteristics
Spark line is low and long, and is sloping. However, there is almost no spark line distortion.
- Cause of problem
Spark plug gap is fouled.




Example 4
- Wave characteristics
Spark line is high and short. Difficult to distinguish between this and abnormal wave pattern example 1.
- Cause of problem
Spark plug cable is not properly connected. (Causing a dual ignition)




Example 5
- Wave characteristics
No waves in wave damping section
- Cause of problem
Layer short in ignition coil.