Starting ignition timing
Starting ignition timing |
The ignition timing is normally set at 10° BTDC, but is retarded when intake air temperature exceeds 4°C. When the temperature of the intake air reaches 100°C, the ignition advance is 3° BTDC. The reason for retarding the ignition when the air temperature rises is because the speed of combustion also increases.
In connection with starting, the control module triggers the relevant cylinder with a 200 Hz signal for 60 crankshaft degrees, whereupon "multisparking" occurs. When engine speed exceeds 450 rpm, the frequency of the signal is increased to 330 Hz. The function is stopped when engine speed exceeds 650 rpm. If engine speed drops below 450 rpm again, he function is re-activated.
The aim is to ensure ignition under unfavourable starting conditions and to prevent the engine dying after starting.