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Synchronize Fuel Injection And Firing Order Function - GF07.10-P-1006MNA

Engine 177.9 in model 205, 253 

Engine 177.9 in model 213 

up to model year 2021 

Function requirements, general 

IMPORTANT The ME-SFI [ME] control unit (N3/10) detects the engine running by evaluating the signals of the crankshaft Hall sensor (B70). The ME-SFI [ME] control unit directly reads in the signals of the crankshaft Hall sensor.

Synchronization of injection and firing order 

Synchronization of the injection and firing order is carried out by the ME-SFI [ME] control unit.

In order to control the synchronization of the injection and firing order, the ME-SFI [ME] control unit evaluates the signals of the following sensors:

The ME-SFI [ME] control unit evaluates the input signals and actuates the following components:

Synchronization 

When starting the engine, the injection sequence is specified to match the firing order. To do this the ignition TDC (Top Dead Center) of cylinder 1 must be recognized.

By the 2nd negative signal edge following the gap in the signal from the crankshaft Hall sensor, the ME-SFI [ME] control unit detects the TDC position of cylinders 1 and 6. If the signal from an intake camshaft Hall sensor is at 0 V (low) at this time, ignition TDC of cylinder 1 is regarded as detected.

IMPORTANT If the voltage signal from an intake camshaft Hall sensor or exhaust camshaft Hall sensor is missing, the voltage signal from another intake camshaft Hall sensor or exhaust camshaft Hall sensor is taken in a certain sequence and used as a substitute to detect the ignition TDC of cylinder 1. If no voltage signal whatsoever is available from an intake camshaft Hall sensor or an exhaust camshaft Hall sensor, injection and ignition take place after a crank angle of 360° in order to make an emergency engine start possible.

Coasting detection 

When the engine is stopped, coasting detection starts, which also detects turning back of the engine just before standstill. During a computer run-on of the ME-SFI [ME] control unit, the determined rest position of the crankshaft is stored in ° crank angle and used for the next engine start. If the coasting detection does not produce a result, or the stopped engine has been turned, the injection and firing order is synchronized when the engine is started.

IMPORTANTEngine speed signal 

The engine speed is derived from the signal of the crankshaft Hall sensor. When the crankshaft is turning, a voltage signal (AC voltage) is generated in the crankshaft Hall sensor by the teeth on the sensor rotor. Here, each tooth generates a voltage pulse. No voltage is generated at the gap where there are 2 missing teeth. The engine speed signal is a square wave signal with a constant duty cycle of 6 pulses (60° crank angle) per engine rotation and a maximum current of approx. 20 mA.

If the voltage signal from the crankshaft Hall sensor fails, the voltage signals from the intake camshaft Hall sensors or the exhaust camshaft Hall sensors are used as a substitute (for limp-home mode).

G13770155Courtesy of MERCEDES-BENZ USA

Diagram of signal assignment and recognition of ignition TDC of cylinder 1 

  Electrical function schematic, synchronization of the injection and firing order Engine 177.9 in model 205, 253 PE07.10-P-2706-97FBD
    Engine 177.9 in model 213 up to model year 2021 PE07.10-P-2706-97DBG
  Overview of system components for gasoline injection and ignition system with direct injection Engine 177.9 in model 205, 253 GF07.70-P-9998MNA
    Engine 177.9 in model 213 up to model year 2021 GF07.70-P-9998MNE
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