Electronic Accelerator Function - GF30.20-P-3015MNC

Engine 276.8 in model 172.4 

Function requirements for the electronic accelerator, general points 

• Circuit 87M (Engine management ON)
• Engine runs

Electronic accelerator, general points 

The electronic accelerator function is integrated into the ME-SFI [ME] control unit (N3/10) and controls the opening angle of the throttle valve dependent upon the driver input and the operating conditions.

The ME-SFI [ME] control unit regulates the throttle valve position, dependent on the following signals:

• Accelerator pedal sensor (B37), accelerator pedal position
• Electronic Stability Program control unit (N30/4), via the chassis CAN 1 (CAN E1):

• Brake actuation
• Cruise control (for CC)

• DISTRONIC electric controller unit (A89) (for code 239 (DISTRONIC PLUS)), engine torque requirement via chassis CAN 1 and Electronic Stability Program control unit
• Fully integrated transmission control unit (Y3/8n4), gear range via drive train CAN (CAN C) (for A/T):

• Gear range
• Reverse travel signal

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 

The ME-SFI [ME] control unit controls the engine torque dependent on a characteristic map, dependent on the accelerator pedal sensor. To do this the ME-SFI [ME] control unit actuates the following assembly parts:

• Actuator motor (M16/6m1) in the throttle valve actuator (M16/6) by means of a pulse width modulated signal
• Ignition coils for cylinders 1 to 6 (T1/1 to T1/6) for regulation of the ignition angle effectiveness over the ignition timing
• Fuel injectors for cylinders 1 to 6 (Y76/1 to Y76/6) for regulation of the lambda value over the fuel quantity

The engine torque is then only determined by the accelerator pedal position if no limited or increased torque requests from other functions or control units (e.g. cruise control 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 signals:

• Accelerator pedal sensor, accelerator pedal actuation (fast, slow)
• Coolant temperature sensor (B11/4)
• Pressure sensor downstream of throttle valve (B28/7), engine load
• Crankshaft Hall sensor (B70), engine RPM
• Sensor elements of left and right oxygen sensor, upstream of catalytic converter (G3/3b1, G3/4b1)
• Sensor elements of left and right oxygen sensor, downstream of catalytic converter (G3/5b1, G3/6b1)
• Electronic Stability Program control unit, wheel speed via chassis CAN 1

Function sequence for reverse travel 

If the ME-SFI [ME] control unit receives the reverse travel CAN signal, the ME-SFI [ME] control unit opens the throttle valves slowly and limits the maximum opening angle to about 50%. This optimizes ride comfort and driving safety in reverse travel.

Function sequence for adaptive accelerator pedal 

The ME-SFI [ME] control unit recognizes how the accelerator pedal is being actuated and switches between two 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 relaxed 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.

	Electrical function schematic for electronic accelerator		PE30.20-P-2050-97TAH
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