GF30.20-P-3012MIK ME-SFI Electronic Accelerator, Function

GF30.20-P-3012MIK ME-SFI Electronic Accelerator, Function
- ENGINE 272.942 in MODEL 171.454 as of Model Year 09 / AEJ 08 model refinement package
- ENGINE 272.969 in MODEL 171.458 as of Model Year 09 / AEJ 08 model refinement package

Function requirements for the electronic accelerator, general points
- Circuit 87M ON (engine control ON)
- Engine running

Electronic accelerator, general points
The electronic accelerator function (EFP) is integrated in the ME-SFI control unit (N3/10), and controls the opening angle of the throttle valve according to driver requests and operating conditions.

The ME-SFI control unit regulates the throttle valve position according to the following sensors and signals:
- Accelerator pedal sensor (B37), accelerator pedal position
- Clutch pedal switch (S40/3), clutch operation (for manual transmission)
- Front SAM control unit with fuse and relay module (N10/1), reverse travel signal over the engine compartment CAN (CAN C) (for manual transmission)
- Electric controller unit (VGS) (Y3/8), gear range over the engine compartment CAN (for automatic transmission)
- Electric controller unit (VGS), reverse travel over the engine compartment CAN (for automatic transmission)
- ESP and BAS control unit (N47-5), brake actuation over the engine compartment CAN
- ESP control unit, cruise control request over the engine compartment CAN (for cruise control)

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

Electronic accelerator function sequence
The function sequence is described in the following steps:
- Throttle valve actuation function sequence
- Throttle valve damping function sequence
- Reverse travel function sequence
- Adaptive accelerator pedal function sequence

Throttle valve actuation function sequence
Depending on the accelerator pedal sensor, the ME-SFI control unit actuates the throttle valve actuator (M16/6) according to a performance map. To do this, it actuates the actuator motor (M16/6m1) in the throttle valve actuator with a PWM signal.
Provided there are no limiting functions active (for example, cruise control request), the opening angle of the throttle valve is determined by the accelerator pedal position alone.
The actual value potentiometers 1 and 2 (M16/6r1, M16/6r2) report the current throttle valve position to the ME-SFI [ME] control unit.

Throttle valve damping function sequence
The ME-SFI control unit controls the throttle valve damping according to the following sensors and signals:
- Accelerator pedal sensor, accelerator pedal actuation (fast, slow)
- Crankshaft Hall sensor (B70), motor speed
- Coolant temperature sensor (B11/4)
- Throttle valve actuator, throttle valve position
- ESP control unit, vehicle speed via engine compartment CAN

The purpose of throttle valve damping is to delay the closing of the throttle valve down to idle speed range if the accelerator pedal is suddenly released. In this way, the engine torque goes down slowly and the vehicle does not slow down with jerks.

Reverse travel function sequence
If the electric controller unit (VGS) or front SAM control unit sends the reverse travel CAN signal, the ME-SFI control unit opens the throttle valve more slowly and limits the maximum opening angle to about 50 %. This optimizes ride comfort and driving safety when reversing.

Adaptive accelerator pedal function sequence
The ME-SFI [ME] control unit recognizes how the accelerator pedal is being actuated and switches between characteristic curves. After a 50% pedal travel, about 80% of the engine load is released for a sporty driver and 40% of the engine load is released for a quiet driver. There is no further difference felt above a pedal travel of about 90%.

If the calm driver characteristic is active (for example, after a long journey on the freeway), the accelerator pedal at first has to be pressed unusually far in order to obtain high acceleration.

Further functions which support the electronic accelerator and which are described in other documents are:
- Idle speed control
- Cruise control (if cruise control installed)
- Engine torque request
- Emergency electronic accelerator pedal