Ignition, Basic Function

Ignition, Basic Function

1. 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.







2. 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.

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. Catalytic converter heating ignition
In order to heat the catalytic converter as quickly as possible after starting, the ignition will be retarded. This is a compensation matrix that is added to the value from box 3. The matrix is dependent on load and engine speed.

5. Engaging catalytic converter heating ignition
The function is active when the coolant temperature is above -10 degree C but below +64 degree C.

6. Total
The value from box 5 is added to the value from box 3.

7. Compensation
The ignition timing is corrected depending on the engine coolant temperature and intake air temperature. The value is sent to box 6.







8. Knock control
If knocking occurs, a timing retardation will be calculated. The value is sent to box 6.

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

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







11. Starting ignition timing
The starting ignition timing is calculated depending on the intake air temperature and the coolant temperature. The value is sent to box 9 via box 7.

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