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

GF30.20-P-3012MIR ME-SFI Electronic Accelerator, Function
- ENGINE 272.949 in MODEL 230.454 as of Model Year 09 /Modification Year 08 model refinement package
- ENGINE 272.968 in MODEL 230.458 as of Model Year 09 /Modification Year 08 model refinement package
- ENGINE 273.965 in MODEL 230.471 as of Model Year 09 /Modification Year 08 model refinement package

Function requirements for the electronic accelerator, general points
- Circuit 87M ON (engine control ON)
- Engine running

Electronic accelerator, general points
The electronic accelerator (EA) function is integrated in the ME-SFI control unit (N3/10), and controls the opening angle of the throttle valve, depending on driver requests and operating conditions.

The ME-SFI control unit regulates the throttle valve position according to the following sensors and signals:
- Accelerator pedal sensor (B37), accelerator pedal position
- Electric controller unit (VGS) (Y3/8), gear range over the engine compartment CAN (CAN C)
- Electric controller unit (VGS), reverse travel via engine compartment CAN
- ESP, SPS [PML] and BAS control unit (N47-5), brake actuation over the engine compartment CAN
- ESP control unit, cruise control request via engine compartment 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 throttle valve actuator (M16/6) according to the accelerator pedal sensor performance map. To do this, the ME-SFI control unit actuates the actuator motor (M16/6m1) in the throttle valve actuator with a PWM signal.
The opening angle of the throttle valve is determined by the accelerator pedal only if no limiting functions are active (for example, cruise control request).
The actual value potentiometers 1 and 2 (M16/6r1, M16/6r2) report the current throttle valve position to the ME-SFI [ME] control unit.

Throttle valve damping function sequence
The ME-SFI control unit controls the throttle valve damping according to the following sensors and signals:
- Accelerator pedal sensor, accelerator pedal action (slow, fast)
- Crankshaft Hall sensor (B70), motor speed
- Coolant temperature sensor (B11/4)
- Throttle valve actuator, throttle valve position
- ESP control unit, vehicle speed via engine compartment 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 ETC electric controller unit sends the "reverse travel" CAN signal over the engine compartment CAN, the ME-SFI control unit opens the throttle valves slowly and limits the maximum opening angle 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 to obtain high acceleration.

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