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

GF07.10-P-1004MMI Injection Regulation, Function
ENGINES 152.9 in MODEL 172.4

Function requirements for injection regulation, general points
^ Circuit 87M (engine timing ON)
^ Engine running

Injection regulation, general points
The engine receives the fuel quantity required in each case from the ME-SFI [ME] control unit (N3/10).

Using the performance map, the ME-SFI [ME] control unit calculates the injection time and pressure on the basis of the following sensors and signals:

- Fuel pressure and temperature sensor (B4/25)
- LH and RH intake camshaft Hall sensors (B6/4, B6/5), intake camshaft positions
- LH and RH exhaust camshaft Hall sensors (B6/6, B6/7), exhaust camshaft positions
- Coolant temperature sensor (B11/4)
- Intake air temperature sensor (B17)
- 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 speed
- LH and RH oxygen sensor sensor elements upstream of catalytic converter (G3/3b1, G3/4b1)
- Altitude 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 time in 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 actuation time of the fuel injectors (Y76) is calculated in the ME-SFI [ME] control unit depending on the lambda control, the rail pressure 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 full load.

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 less than 2000 rpm
- Keeping catalytic converters warm when engine idles for long period

Function sequence for acceleration
When there is rapid variation of the accelerator pedal position, the throttle valve also opens and closes rapidly. This causes the mixture to become briefly leaner or more rich.
To prevent this, the ME-SFI [ME] control unit adapts the fuel-air mixture, by shortening or lengthening the actuation time of the fuel injectors according to a performance map. This prevents jerking of the engine.