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

Engine 274.9 in model 205 (except 205.047/053/054/147/247/253) 

Engine 274.9 in model 253 (except 253.354/954) 

Function requirements for injection regulation, general points 

• Circuit 87M (Engine management ON)
• Engine runs

Injection regulation, general points 

The ME-SFI [ME] control unit (N3/10) assigns the required fuel quantity to the engine.

Using the characteristic map, the ME-SFI [ME] control unit calculates the injection period and pressure based on the following signals:

• Fuel pressure and temperature sensor (B4/25)
• intake camshaft Hall sensor (B6/15), intake camshaft setting
• Exhaust camshaft Hall sensor (B6/16), exhaust camshaft setting
• Coolant temperature sensor (B11/4)
• Charge air temperature sensor upstream of throttle valve (B17/7)
• Charge air temperature sensor downstream of throttle valve (B17/9)
• Pressure sensor downstream of throttle valve (B28/7), engine load
• Accelerator pedal sensor (B37), driver engine load request
• Accelerator pedal sensor, accelerator pedal operation fast or slow (when accelerating)
• Crankshaft Hall sensor (B70), engine RPM
• Sensor element for oxygen sensor downstream of catalytic converter and sensor element for oxygen sensor upstream of catalytic converter (G3/1b1, G3/2b1)
• Atmospheric pressure sensor in ME-SFI [ME] control unit, atmospheric pressure for altitude adaptation
• Correction programming using XENTRY diagnostics

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

Function sequence for injection regulation 

The ME-SFI [ME] control unit controls the injection period under the following operating conditions:

• Function sequence for partial load and wide open throttle operation 
• Function sequence for acceleration 

Function sequence for partial load and wide open throttle operation 

The ME-SFI [ME] control unit calculates the actuation time of the cylinder 1 injection nozzle to cylinder 4 injection nozzle (Y76/1 to Y76/4) dependent on the lambda control, the fuel pressure in the rail and the requested engine torque.

At the accelerator pedal sensor, about 10 to 90% slewing range is defined as partial load and more than about 90% slewing range is defined as wide open throttle.

Multiple injection

Partitioning the injection quantity into a number of single fuel injections, whereby the last can be selected to be close to ignition.

Areas of application of multiple injections:

• Start
• Heat up catalytic converters
• Combustion stabilization at high loads and speeds <2000 RPM
• Keeping catalytic converters warm when engine idles for long period

Function sequence for acceleration 

When there is rapid change in the accelerator pedal position, the throttle valve also opens and closes rapidly. This causes the mixture to become briefly leaner or too rich.

To prevent this, the ME-SFI [ME] control unit adapts the fuel/air mixture by lengthening or shortening the actuation time of the fuel injectors according to a characteristics map. This prevents jerking of the engine.

	Electrical function schematic for injection control		PE07.10-P-2704-97FBA
	Overview of system components for gasoline injection and ignition system with direct injection		GF07.70-P-9998MRA