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

Engine 276.8 in model 205, 253 

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 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), brake actuation, cruise control requests and engine torque requests via the chassis FlexRay (Flex E), powertrain control unit (N127) and drive train CAN (CAN C1)
• Fully integrated transmission control unit (Y3/8n4), gear range and reverse travel signal via 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 drivability functions 
• Function sequence for reverse travel 
• Function sequence for adaptive accelerator pedal 

Function sequence for engine torque specification 

The ME-SFI [ME] control unit actuates 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 components:

• Throttle valve actuator motor (M16/6m1) in throttle valve actuator (M16/6) over a pulse width modulated signal
• Ignition coils (T1/1 up to T1/6) for regulation of the ignition angle efficiency over the ignition timing
• Fuel injectors (Y761 to Y766) for regulation of the lambda value via the fuel mass

The engine torque is then only determined by the accelerator pedal position if no limited or increased engine 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 drivability functions 

The drivability 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 drivability 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)
• LH and RH oxygen sensor, sensor elements upstream of catalytic converter (G3/3b1, G3/4b1), oxygen and nitrogen contents
• LH and RH oxygen sensor, sensor elements downstream of catalytic converter (G3/5b1, G3/6b1), oxygen and nitrogen contents
• Electronic Stability Program control unit, vehicle speed over suspension FlexRay, powertrain control unit and drive train CAN

Function sequence for reverse travel 

If the fully integrated transmission control unit sends the CAN signal "reverse travel" via drive train CAN, the engine torque is limited to approx. 50 % by the ME-SFI [ME] control unit. This optimizes ride comfort and driving safety in 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, are:

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

	Electrical function schematic for electronic accelerator		PE30.20-P-2050-97FBB
	Overview of system components for gasoline injection and ignition system with direct injection		GF07.70-P-9998MMV