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

Engine 157.9, 276.8, 278.9 in model 217, 222 (except 222.163/173) 

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 signals:

• Accelerator pedal sensor (B37), accelerator pedal position
• Electronic Stability Program control unit (N30/4), via the suspension FlexRay (Flex E), powertrain control unit (N127) and drive train CAN (CAN C1)
  • Brake actuation
  • Cruise control request
  • Engine torque request
• Radar sensors control unit (N62/1) (with code P20 (Driving Assistance package Plus)) via suspension FlexRay, powertrain control unit and drive train CAN
  • Engine torque request (increasing or reducing)
• Fully integrated transmission control unit (Y3/8n4) via the drive train CAN
  • Drive position
  • 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 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 controls the engine torque dependent on a characteristic map, dependent on the accelerator pedal sensor. To do this the ME-SFI [ME] control unit controls the following functions:

• Regulate throttle valve position by means of actuator motor (M16/6m1) in throttle valve actuator (M16/6) via a pulse width modulated signal.
• Regulation of ignition angle efficiency (results from shift of actual ignition angle from optimal ignition angle) via ignition timing by means of
  • Cylinder 1 to 6 ignition coils (T1/1 to T1/6) (for engine 276.8)
  • Cylinder 1 to 8 ignition coils (T1/1 to T1/8) (for engine 157.9, 278.9)
• Regulation of lambda value via fuel quantity per
  • Cylinder 1 to 6 fuel injectors (Y76/1 to Y76/6) (for engine 276.8)
  • Cylinder 1 to 8 fuel injectors (Y76/1 to Y76/8) (for engine 157.9, 278.9)
• Regulation of boost pressure per charge-air pressure control pressure transducer (Y77/1)

Engine torque is only determined solely by accelerator pedal position if no limiting or increasing 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 signals:

• Accelerator pedal sensor, accelerator pedal actuation (fast, slow)
• Crankshaft Hall sensor (B70), engine rpm
• Coolant temperature sensor (B11/4), coolant temperature
• Pressure sensor downstream of throttle valve (B28/7), boost pressure
• Throttle valve actuator, throttle valve position
• 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).

	Electrical function schematic for electronic accelerator	Engine 157.9, 278.9 in model 217, 222	PE30.20-P-2050-97SED
		Engine 276.8 in model 217, 222 (except 222.163/173)	PE30.20-P-2050-97SEE
	Overview of system components for gasoline injection and ignition system with direct injection	Engine 157.9, 278.9 in model 222	GF07.70-P-9998MML
		Engine 276.8 in model 217, 222 (except 222.163/173)	GF07.70-P-9998MMT