Injection Regulation, Function - GF07.10-P-1004MRS

Engine 264.9 in Model 205, 253 

Function requirements, general 

• Engine runs

The ME-SFI [ME] control unit (N3/10) detects the Engine running via the evaluation of the crankshaft Hall sensor signals (B70). The ME-SFI [ME] control unit directly reads in the signals of the crankshaft Hall sensor.

Injection control 

The injection control distributes the required fuel quantity to each cylinder in a demand-based way. The fuel quantity results from the injection duration and the injection pressure when doing this.

The ME-SFI [ME] control unit calculates the injection duration and injection pressure based on the following signals:

• Fuel pressure and temperature

  Fuel pressure and temperature sensor (B4/25)

• Intake camshaft position

  Intake camshaft Hall sensor (B6/15)

• Exhaust camshaft position

  Exhaust camshaft Hall sensor (B6/16)

• Coolant temperature

  Coolant temperature sensor (B11/4)

• Engine load

  Pressure and temperature sensor downstream of throttle valve (B28/27)

• Engine loading request

  The powertrain control unit (N127) reads in the accelerator pedal sensor (B37) signals directly, and transmits the accelerator pedal position via the drive CAN (CAN C1) to the ME-SFI [ME] control unit.

• Engine speed

  Crankshaft Hall sensor

• Nitrogen oxide and oxygen concentration in exhaust gas

  Oxygen sensor downstream of catalytic converter (G3/1)

  • Oxygen sensor sensor element downstream of catalytic converter (G3/1b1)

    Oxygen sensor upstream of catalytic converter (G3/2)

  • Oxygen sensor sensor element upstream of catalytic converter (G3/2b1)
• Atmospheric pressure for altitude adaptation

  The atmospheric pressure sensor is integrated in the ME-SFI [ME] control unit.

The requirements of the torque coordination function are also taken into account.

The ME-SFI [ME] control unit actuates the following components for the injection control:

• Cylinder 1 fuel injector (Y76/1)
• Cylinder 2 fuel injector (Y76/2)
• Cylinder 3 fuel injector (Y76/3)
• Cylinder 4 fuel injector (Y76/4)

The ME-SFI [ME] control unit makes a distinction between the following operating conditions when doing this:

• Engine start 
• Idle speed 
• Partial load, full load 
• Accelerate 

The Engine start and idle operating conditions are described in separate documents.

Partial load, full load 

The ME-SFI [ME] control unit calculates the actuation time of the fuel injectors depending on lambda control, the fuel pressure in the rail, and the requested Engine torque.

At the accelerator pedal sensor, the approx. 10 to 90 % slewing range is defined as partial load while the more than approx. 90 % slewing range is defined as full load.

Multiple injection 

With multiple injection, the fuel injectors are actuated multiple times in succession. The injection quantity is distributed to multiple single fuel injections.

Multiple injections can occur with the following actions:

• Start
• Heat up CAT
• Combustion stabilization at high loads and Engine speeds above 2000 RPM
• Keep the CAT in idle for long idling phases for a run Engine

Accelerate 

When there is rapid change in the accelerator pedal position, the throttle valve also opens and closes rapidly. This causes the mixture to briefly become leaner or too rich. To prevent this, the ME-SFI [ME] control unit adjusts the fuel/air mixture by increasing or shortening the actuation time of the fuel injectors in a characteristics map-dependent manner. This prevents Engine jolting.