Electronic Throttle Actuator: Description and Operation
GF30.20-P-3015MG Electronic Accelerator Function
ENGINES 271.8 in MODEL 204.0 /2 /3, 207.3 /4, 212.0 /2
Function requirements for the electronic accelerator, general points
^ Circuit 87 M ON (engine timing ON)
^ Engine running
Electronic accelerator, general points
The electronic accelerator function (EFP) is integrated in the ME-SFI [ME] control unit (N3/10), and controls the opening angle of the throttle valve according to driver requests and operating conditions.
The ME-SFI [ME] control unit regulates the throttle valve position according to the following sensors and signals:
- Accelerator pedal sensor (B37), accelerator pedal position
- Front SAM control unit with fuse and relay module (N10/1), reverse travel signal from backup lamp switch (S16/2) via the chassis CAN (CAN E) (for a manual transmission)
- Electronic Stability Program control unit (N30/4) (except code (233) DISTRONIC PLUS) or Electronic Stability Program Premium control unit (N30/7) (with code (233) DISTRONIC PLUS), brake actuation via the chassis CAN
- Electronic Stability Program control unit or Electronic Stability Program Premium control unit, request to the CC via the chassis CAN (for CC)
- The electronic transmission control control unit (N15/3) (for code (423) 5-speed automatic transmission (NAG)) or fully integrated transmission control controller unit (Y3/8) (for code (427) 7-speed automatic transmission), gear range via the drive train CAN (CAN C)
- Electronic transmission control control unit or fully integrated transmission control controller unit, signal for reverse travel via the drive train CAN
- Radar sensors control unit (N62/1) (model 207.3/4 up to 31.5.11 with code (233) DISTRONIC PLUS, model 212.0/2 up to 31.5.10 with code (233) DISTRONIC PLUS or code (234) Blind Spot Assist) or video and radar sensor system control unit (N62/2) (model 212.0/2 as of 01.06.10, model 204.0/2 and model 207.3/4 as of 01.06.11, model 204.3 with code (233) DISTRONIC PLUS, with code (237) Active Blind spot Assist, with code (238) Active Lane Keeping Assist), DISTRONIC request via the chassis CAN
- Clutch pedal switch (S40/3), clutch operation (for manual transmission)
The requirements of the torque coordination function are also taken into account.
The Electronic Stability Program control unit (N30/4) will be introduced into service as of 1.3.2011 (model 204.0/2) or as of 1.6.2011 (model 204.3) in 2 variants:
- Electronic Stability Program control unit, Basis variant (except code (233) DISTRONIC PLUS)
- Electronic Stability Program control unit, Premium variant (except code (233) DISTRONIC PLUS)
Up to 28.2.2011 or 31.5.2011 only the Electronic Stability Program control unit basic variant will be used.
Function sequence for electronic accelerator
The function sequence is described in the following steps:
^ Function sequence for throttle valve actuation
^ Function sequence for throttle valve damping
^ Function sequence for reverse travel
^ Function sequence for adaptive accelerator pedal
Function sequence for throttle valve actuation
Depending on the accelerator pedal sensor, the ME-SFI [ME] control unit actuates the throttle valve actuator (M16/6) according to a performance map. To do this, the ME-SFI [ME] control unit operates the actuator motor (M16/6m1) in the throttle valve actuator with a pulse width modulated signal (PWM signal).
Provided there are no limiting functions active (for example, cruise control request), the opening angle of the throttle valve is determined by the accelerator pedal position alone. 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 throttle valve damping
The ME-SFI [ME] control unit controls the throttle valve damping according to the following sensors and signals:
- Accelerator pedal sensor, accelerator pedal actuation (fast, slow)
- Crankshaft Hall sensor (B70), engine speed
- Coolant temperature sensor (B11/4)
- Throttle valve positioner, throttle valve position
- Electronic Stability Program control unit, wheel speed via the chassis CAN
The purpose of throttle valve damping is to delay closing of the throttle valve down to idle speed range if the accelerator pedal is suddenly released. In this way, the engine torque reduces slowly and the vehicle does not slow down with jerks.
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 when reversing.
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.
Further functions which support the electronic accelerator and which are described in other documents are:
- Engine speed control
- Cruise control (if cruise control installed)
- DISTRONIC PLUS (for DISTRONIC PLUS)
- Torque coordination
- Engine limp-home mode
