Ignition, basic function
- Idling speed ignition timing
With idle speed control active, the timing is adjusted to stabilize the idling speed. The value is sent to box 3.
- Normal ignition timing
When idle speed control is inactive, the ignition timing is read from a load and engine speed dependent matrix. The value from the matrix is optimized for the lowest fuel consumption (best engine torque). The value is sent to box 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.
- Catalytic converter heating timing
In order to heat up the catalytic converter as fast as possible after start, the ignition will be retarded. This is a compensation matrix that is added to the value in box 3. The matrix is dependent on load and engine speed.
- Engagement of catalytic converter preheating timing
The function is active when the coolant temperature is above -10°C but below +64°C.
- Total
The value from box 5 is added to the value from box 3.
- Compensation
The ignition timing is corrected depending on the engine coolant temperature and intake air temperature. The value is sent to box 6.
- Knock control
If knocking occurs, a timing retardation will be calculated. The value is sent to box 6.
- Total
The compensation angle and knock retardation are totalled to give the current ignition timing. The value is sent to box 7.
- Selection of ignition timing
Starting ignition timing is selected when the engine has not yet been started. The value is sent to box 9.
- Starting ignition timing
Initial ignition timing is calculated depending on intake air temperature and engine coolant temperature. The value is sent to box 9 via box 7.
- Activate relevant trigger
At the calculated crankshaft angle, the microprocessor controls the transistor for the trigger that is next in the firing order.