Ignition System: Description and Operation

GF15.12-P-0001V ME-SFI Ignition System, Function











Cylinder arrangement and ignition firing order

The ME-SFI control unit essentially analyzes the following signals for determining the ignition angle:
- Air mass
- Position and rpm of crankshaft
- Positions of intake camshafts
- Positions of exhaust camshafts
- Coolant temperature
- Intake air temperature
- Knock sensor signals
- Intake manifold air pressure
- Engine torque requests

The ME-SFI [ME] control unit interrupts the respective ignition coil at the moment of the ignition timing of the primary circuit to "terminal 1".

Ignition angle adaptation
For the following partial functions an ignition angle adjustment in the direction "retarded" or "advanced" can take place:
- Catalytic converter heating-up
- Idle speed control
- Overheating / knock protection
- Deceleration fuel shutoff
- Transmission overload protection (with automatic transmission 722.9)
- Anti-knock control [AKC]
- Engine torque requests

The ignition angle can only be checked using the DAS.