Ignition Secondary Volt. Wave Pattern Check Using Oscilloscope
MEASUREMENT METHOD1. Clamp the spark plug cable of the number 1 cylinder with the secondary pickup and check the wave patterns for each cylinder.
2. Connect the secondary pickup to the other cylinder in turn and check the wave patterns for each cylinder.
Standard Wave Pattern:
WAVE FORM OBSERVATION POINTS
NOTE: Abnormal wave form examples are shown subsequently
Point A:
The height, length and slope of the spark line (refer to abnormal wave form examples 1, 2, 3 and 4) show the following trends.
Point B:
Number of vibrations in reduction vibration section (Refer to Abnormal Wave form 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 WAVE FORMS 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.