Injection regulation, function

Function requirements for injection regulation, general points

 Circuit 87M (engine control ON)

 Engine running

Injection regulation, general points

The ME-SFI [ME] control unit (N3/10) calculates the individual injection signals (valve opening time and valve opening duration), dependent on the characteristic map, for each injection nozzle (Y76) or for each gas injection valves gas (Y106). The ME-SFI [ME] control unit directly actuates the injection valves and transmits the injection signals of the gas injection valves gas via the CNG control unit (N118/2).

Calculation of the injection signals based on the following sensors and signals:

- Fuel pressure and temperature sensor (B4/25)

- 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)

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- intake camshaft Hall sensor (B6/15), intake camshaft setting

- exhaust camshaft Hall sensor (B6/16), exhaust camshaft setting

- 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) (with direction of rotation recognition), motor rpm

- sensor element for oxygen sensor upstream of catalytic converter (G3/2b1)

- Altitude pressure sensor in ME-SFI [ME] control unit, atmospheric pressure for altitude adaptation

- correction programming with the Xentry diagnostics (during acceleration)

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

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Function sequence for injection regulation

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

 Function sequence for partial load operation

 Function sequence for wide open throttle operation

 Function sequence for acceleration

Function sequence for partial load operation

In partial load operation when the engine is warm, the ME-SFI [ME] control unit calculates the actuation time of the fuel injectors or the gas injection valves gas dependent on the lambda control, the rail pressure and the requested engine torque.

Function sequence for wide open throttle operation

During wide open throttle operation the ME-SFI [ME] control unit extends the actuation time of the fuel injectors or the gas injection valves gas for a fully opened throttle valve and increases the injection pressure in order to ensure maximum engine torque.

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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.

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 richer.

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 or the gas injection valves gas according to a performance map. This prevents jerking of the engine.