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ME-SFI synchronization of fuel injection and firing order, function - GF07.61-P-4009MOS

ENGINE 275.953 in MODEL 216.376, 221.176 as of Model Year 09 /AEJ 08 

ENGINE 275.982 in MODEL 216.379, 221.179 as of Model Year 09 /AEJ 08 

Function requirements synchronization of fuel injection and firing order, general points 

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 (N3/10) in order to actuate the ECI ignition modules of the RH and LH cylinder banks (N92/1, N92/2) and the fuel injection valves (Y62).

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:

Synchronization of the fuel injection and firing order, function sequence 

When the engine is stared, the injection sequence is determined according to the firing order in the voltage signals from the crankshaft position sensor and camshaft Hall sensor. To do this, ignition TDC (Top Dead Center) must be detected in cylinder 1.

The ME-SFI control unit detects TDC position in cylinders 1 and 6 on the 2nd. negative signal edge after the gap in the signal from the crankshaft position sensor. If the signal from the Hall sensor camshaft is at 0 V (low) at this time, the ME-SFI control unit processes it in order to detect ignition TDC in cylinder 1.

IMPORTANT If the voltage signal from the Hall sensor camshaft fails, ignition and injection take place after 360° CKA (CranK Angle), in order to allow an emergency start.

Signal assignment 

Fig 1: Identifying Signal Assignment For ME-SFI Synchronization Of Fuel Injection And Firing Order
G07537682Courtesy of MERCEDES-BENZ USA
REFER TO SYSTEM WIRING DIAGRAMS Electrical function schematic, synchronization of the injection and firing order ME Model 216 PE07.61-P-2771-97CAA
Model 221 PE07.61-P-2771-97SAA
  ME-SFI [ME] control unit, component description N3/10 GF07.61-P-6000MOS