Electronic accelerator function - GF30.20-P-3015MMA

ENGINE 157.9 in MODEL 212, 218 up to model year 2014 

ENGINE 278.9 in MODEL 207, 212, 218 up to model year 2014 

Function requirements for the electronic accelerator, general points 

• Circuit 87M (engine timing ON)
• Engine runs

Electronic accelerator, general points 

The electronic accelerator function is integrated in the ME-SFI [ME] control unit (N3/10) and controls the engine torque depending on the driver command and the operating conditions.

The ME-SFI [ME] control unit regulates the engine torque, dependent on the following sensors and signals:

• Accelerator pedal sensor (B37), accelerator pedal position
• Electronic Stability Program control unit (N30/4) (except code 233 (DISTRONIC PLUS) or Electronic Stability Program Premium control unit (N30/7) (for code 233 (DISTRONIC PLUS), brake actuation via chassis CAN (CAN E)
• Electronic Stability Program control unit cruise control request, over the chassis CAN
• Video and radar sensor system control unit (N62/2) (for code 233 (DISTRONIC PLUS), for code 237 (Active Blind Spot Assist), for code 238 (Active Lane Keeping Assist), engine torque request via the chassis CAN
• Fully integrated transmission control controller unit (Y3/8), gear range over drive train CAN (CAN C)
• Fully integrated transmission controller unit, reverse travel signal via the drive train CAN

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

Function sequence for electronic accelerator 

• The function sequence is described in the following steps:
• Function sequence for engine torque specification 
• Function sequence for driveability functions 
• Function sequence for reverse travel 
• Function sequence for adaptive accelerator pedal 

Function sequence for engine torque specification 

Depending on the accelerator pedal sensor, the ME-SFI [ME] control unit actuates the throttle valve actuator (M16/6) according to a characteristics map. To do this the ME-SFI [ME] control unit controls the actuator motor (M16/6m1) in the throttle valve actuator by means of a pulse width modulated signal (PWM signal), the effectiveness of the ignition angle over the ignition timing of the ignition coils (T1) and spark plugs (R4), the boost pressure over the boost pressure controller pressure transducer (Y77/1). The engine torque is then not only determined by the accelerator pedal specification, if no limited or increased torque requests from other functions or control units (for example CC request) are active. The actual value potentiometers 1 and 2 (M16/6r1, M16/6r2) report the current throttle valve position to the ME-SFI [ME] control unit.

Function sequence for driveability functions 

The driveability functions and throttle change damping have the task of limiting the change of engine torque as a result of a rapid movement of the accelerator pedal. The limitation serves to improve the ride comfort since jolting in the drivetrain is prevented.

The driveability functions and the throttle change damping take place on the basis of the following sensors and signals:

• Accelerator pedal sensor, accelerator pedal actuation (fast, slow)
• Crankshaft Hall sensor (B70), engine rpm
• Coolant temperature sensor (B11/4) (model 207, 212), coolant temperature sensor (B11/4) (model 218)
• Pressure sensor downstream of the throttle valve (B28/7), intake manifold pressure
• Throttle valve positioner, throttle valve position
• Electronic Stability Program control unit, wheel speed via the chassis CAN

Function sequence for reverse travel 

If the fully integrated transmission control controller unit sends the CAN signal "Reverse travel" over drive train CAN, the ME-SFI [ME] control unit restricts the engine torque to approx. 50 %. This optimizes ride comfort and driving safety when reverse travel.

Function sequence for adaptive accelerator pedal 

The ME-SFI [ME] control unit changes the response time of the accelerator pedal depending on the vehicle speed calculated from the wheel speed. At higher vehicle speeds a somewhat steeper accelerator pedal curve is used in order to improve the response time (reduction of the free travel).

Further functions which support the electronic accelerator and which are described in other documents are:

• Engine speed control
• Torque coordination
• Engine limp-home mode