Starting ignition timing
Starting ignition timing |
Ignition timing is normally 10° BTDC but is retarded when the intake air temperature exceeds 4°C. When the intake air temperature reaches 100°C, the ignition advance is 3° BTDC. The reason for the ignition being retarded when the air temperature increases is that then the combustion velocity also increases.
When starting, the control module triggers the respective cylinder with 200 Hz for 60 crankshaft degrees, whereby a so-called multispark occurs. When the engine speed exceeds 450 rpm, the frequency will be increased to 330 Hz. The function is interrupted when the engine speed exceeds 650 rpm and is reactivated once the engine speed drops below 450 rpm.
This is to ensure ignition in unfavourable starting conditions and to prevent the engine from stalling directly after start.