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 Totalling
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
The ignition timing at start is calculated based on the intake air temperature and coolant temperature. If the engine is running the value is sent via box 7 to box 9.

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