Objective:
Determining ignition faults by analysing the ignition voltage plot for each of the cylinders.
Measurement:
Plot of the ignition voltage of one cylinder when the engine is idling (single display).
Preparation:
Caution - high voltage! Observe safety advice!
Engine at operating temperature.
Connections:
| INPUT A | COM/TRIGGER | INPUT B |
|---|---|---|
| Clamp secondary measurement sensor across the ignition lead of the cylinder under test. Connect ground connection to ground. |
Procedure Tech 31:
- 1. Download the Reference curve.
- 2. Start the engine and allow it to idle.
Reference Curve:
Positive and negative ignition voltages occur on DIS ignition coils systems. This can be easily recognised, as the ignition voltage spike for the negative polarity cylinders points downwards.
If this occurs, pressing the invert key turns the ignition voltage graph.
The evaluation mainly considers the ignition voltage spike and the combustion voltage plot. To get a better view the horizontal scaling factor can be changed to 500 micro seconds / Div.
