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

GF30.20-P-3012MAS ME-SFI Electronic Accelerator, Function
- ENGINE 156.984 in MODEL 216.377, 221.077 /177 as of Model Year 09 /AEJ 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 (EFP) (N3/10) integrated in the ME-SFI control unit and controls the opening angles of the throttle valves according to driver requirements and operating conditions.

The ME-SFI control unit controls the throttle valve positions according to the following sensors and signals:
- Accelerator pedal sensor (B37), accelerator pedal position
- ESP control unit (N47-5), brake actuation over the chassis CAN (CAN E)
- ESP control unit, cruise control request over the chassis CAN
- Radar sensors control unit (SGR) (N62/1), Distronic request over the chassis CAN (for Distronic PLUS)
- Electric controller unit (VGS) (Y3/8), gear range over the drive train CAN (CAN C)
- Electric controller unit (VGS), reverse travel over the drive train CAN

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
The ME-SFI control unit actuates the front and rear throttle valve actuators (M16/3, M16/4) according to the accelerator pedal sensor performance map. To do this, the ME-SFI control unit simultaneously actuates the actuator motors (M16/3m1, M16/4m1) in the throttle valve actuators with a pulse width modulated (PWM) signal.

The opening angles of the throttle valves are only determined by the accelerator pedal parameters if there are no limiting functions active (for example, cruise control request).

Actual value potentiometers 1 and 2 (M16/3r1, M16/4r1, M16/3r2, M16/4r2) send the current throttle valve positions to the ME-SFI control unit.

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

The purpose of throttle valve damping is to delay the closing of the throttle valves down to the idle speed range if the accelerator is released suddenly. 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) sends the "reverse travel" CAN signal over the drive train CAN, the ME-SFI control unit slowly opens the throttle valves and limits the opening angles 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.

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