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

GF30.20-P-3012MIS ME-SFI Electronic Accelerator, Function
- ENGINES 272.9 in MODEL 221.0 /1 as of model year 2009 /YoM 08
- ENGINES 273.9 in MODEL 216.3, 221.0 /1 as of model year 2009 /YoM 08

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

Electronic accelerator, general points
The electronic accelerator function is integrated and controlled in the ME-SFI control unit (N3/10) depending on the driver input and the operating condition, the opening angle of the throttle valve.

The ME-SFI [ME] control unit regulates the throttle valve position according to the following sensors and signals:
- Accelerator pedal sensor (B37), accelerator pedal position
- Electric controller unit (VGS) (Y3/8), gear range over the engine compartment (CAN C)
- Electric controller unit (VGS), reverse travel signal via drive CAN
- ESP control unit (N47-5) or regenerative braking system (N30/6) (for hybrid), brake actuation via chassis CAN (CAN E)
- ESP control unit or regenerative braking system (for hybrid), cruise control request via chassis CAN
- Radar sensor control unit (SGR) (N62/1), DISTRONIC request via chassis CAN (for DISTRONIC PLUS)

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 [ME] control unit actuates the throttle valve actuator (M16/6) according to a performance map. To do this, the ME-SFI control unit operates the actuator motor (M16/6m1) in the throttle valve actuator with a pulse width modulated signal (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 [ME] 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), engine speed
- Coolant temperature sensor (B11/4)
- Throttle valve actuator, throttle valve position
- ESP control unit or regenerative braking system (for hybrid), vehicle speed via chassis CAN

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

Reverse travel function sequence
If the ETC electric controller unit sends the "reverse travel" CAN signal over the drive compartment CAN, the ME-SFI control unit opens the throttle valves 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
- DISTRONIC PLUS (for DISTRONIC PLUS)
- Engine torque request
- Emergency electronic accelerator pedal