Ignition, Basic Function

Ignition, basic function







1 Idling speed ignition timing
When the idle speed control is active, the ignition timing is adjusted to stabilize idling speed. The value is sent to box 3.

2 Normal ignition timing
When the idle speed control is not active, the ignition timing is obtained from a load- and speed-dependent matrix. The matrix value is optimized for the lowest fuel consumption (best torque). The value is sent to box 3.

3 Selection of ignition timing
One of the ignition timing calculations is selected, depending on which function is active. The value is sent to box 6.







4 Compensation
The timing is corrected according to the coolant temperature and intake air temperature. The value is sent to box 6.

5 Knock control
If knocking occurs, the amount by which the ignition should be retarded is calculated. The value is sent to box 6.

6 Total
The compensation angle and knock retardation are totalled to give the current ignition timing. The value is sent to box 7.







7 Selection of ignition timing
Starting ignition is selected when the engine has not yet started. The value is sent to box 9.

8 Starting ignition timing
Starting ignition timing is calculated from the intake air temperature and the coolant temperature. The value is sent to box 9.

9 Activate relevant trigger
At the calculated crankshaft angle, the microprocessor controls the transistor for the trigger which is next in the firing order.