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

ENGINE 273.961 in MODEL 216, 221 up to Model Year 8 

Shown on ENGINE 272 

Fig 1: ME-SFI Synchronization Of Fuel Injection And Firing Order Function Diagram
G07634040Courtesy of MERCEDES-BENZ USA

When the engine is started, the injection sequence is defined on the basis of the firing order signals supplied by the crankshaft Hall sensor and the camshaft Hall sensors To do this, ignition TDC must be detected by cylinder 1.

The synchronization of the injection and firing order is further processed by the ME control unit for actuating the ignition coils and the fuel injection valves. In addition, it is required for the anti-knock control and for the fuel cutoff at individual cylinders.

IMPORTANT If the camshaft Hall sensors are defective, a switchover to the next sensor will take place in a particular sequence. If there is no signal available then ignition occurs after a 360° crank angle and injection occurs 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. When the computer powers down, the position found is saved as ° crankshaft angle and used the next time the engine is started. If coasting detection does not provide a result, or the shutdown engine has been moved, synchronization takes place.

Shown on ENGINE 272 

Fig 2: ME-SFI Synchronization Of Fuel Injection And Firing Order Voltage Signals Chart (Engine 272)
G07008094Courtesy of MERCEDES-BENZ USA

Shown on ENGINE 273 

Fig 3: ME-SFI Synchronization Of Fuel Injection And Firing Order Voltage Signals Chart (Engine 273)
G07634042Courtesy of MERCEDES-BENZ USA
Component description for the ME-SFI [ME] control unit GF07.61-P-6000V 
Component description for the crankshaft Hall sensor GF07.04-P-6220V 
Component description for the camshaft Hall sensor GF07.04-P-6020V