GF07.61-P-4009MAS ME-SFI Synchronization of Fuel Injection and Firing Order, Function

GF07.61-P-4009MAS ME-SFI Synchronization Of Fuel Injection And Firing Order, Function
- as of model year 09


Function requirements synchronization of fuel injection and firing order, general points
^ Circuit 87M ON (engine control ON)
^ The engine turns

Synchronization of the fuel injection and firing order, general points
Synchronization of the injection and firing order is processed by the ME-SFI control unit in order to actuate the ignition coils (T1) and fuel injection valves (Y62)N3/10
Furthermore the synchronization is required for the knock control and the fuel shutoff on the individual cylinders.

The ME-SFI control unit synchronizes the injection and firing using the signals from the following sensors:
- Crankshaft Hall sensor (B70), engine speed and crankshaft position
- LH and RH intake camshaft Hall sensors (B6/4, B6/5), intake camshaft positions
- LH and RH exhaust camshaft Hall sensors (B6/6, B6/7), exhaust camshaft positions

Synchronization of the fuel injection and firing order, function sequence
When the engine is started, the injection sequence is determined according to the firing order, using the voltage signals from the crankshaft Hall sensor and the intake camshaft or exhaust camshaft Hall sensors. To do this, ignition TDC ( Top Dead Center) must be detected in cylinder 1.
The ME-SFI control unit detects TDC position of cylinders 1 and 6 on the 2nd negative signal edge following the gap in the signal from the crankshaft Hall sensor. If the signal from an intake camshaft Hall sensor is at 0 V (low) at this time, the ME-SFI control unit processes it in order to detect ignition TDC in cylinder 1.

If the voltage pulse is missing from a camshaft Hall sensor the voltage pulse will be used as a substitute in a certain sequence by another camshaft Hall sensor for recognition of the ignition TDC of cylinder 1.
If no voltage signal is available from any of the camshaft Hall sensors, ignition and injection take place after 360° CKA ( CranK Angle) in order to allow an emergency start.

When the engine is shut down, coasting detection takes place, which also evaluates turning back of the engine shortly before the engine is stationary. During a computer run on by the ME-SFI [ME] control unit, the found rest position of the crankshaft as a °crank angle is stored and used for the next engine start. If coasting detection does not produce a result, or the engine has been turned while shut down, injection and firing order are synchronized at engine start.

Component Identification: