Engine Timing Start-Stop Function - GF07.10-P-1041MMK

Engine 276.8 in model 222.163/173 

Engine 276.9 in model 222 

The ECO start/stop function is divided into scopes at the engine, at the 12 V on-board electrical system and at the hybrid system.

The partial function "engine timing Start-Stop function" is considered and described from the point of view of the engine management for the internal combustion engine.

The ME-SFI [ME] control unit (N3/10) continuously performs a system diagnosis and assesses the function requirements for the ECO start/stop function. All of the systems participating in the function continuously check their status and transmit this via the Control Area Network (CAN) network to the ME-SFI [ME] control unit.

If the function requirements are fulfilled, the driver is notified of readiness to operate of the hybrid drive system from the "READY" symbol in the instrument cluster (A1).

Function requirements for engine management, start/stop function, general points 

• Engine hood closed
• Hybrid drive system "READY"
• No emergency braking has occurred
• No Crash event occurred in the driving cycle
• System diagnosis complete and fault-free

Engine management start-stop function, general 

Conventional switching off of the internal combustion engine in request by the driver over the electronic ignition lock control unit (N73) is still possible.

Conventional starting of the internal combustion engine is requested by the driver. The internal combustion engine will only be started however it is necessary from the point if view of system optimization.

The ME-SFI [ME] control unit reads in the following sensors and signals to control the internal combustion engine for the ECO start/stop function:

• Coolant temperature sensor (B11/4)
• Accelerator pedal sensor (B37), accelerator pedal actuation
• Pedal angle sensor (B37/1) via the Electronic Stability Program control unit (N30/4), brake pedal actuation
• Crankshaft Hall sensor (B70), engine rpm
• Fuel system control unit (N118), fuel pressure via the drive train CAN (CAN C1)
• Fully integrated transmission control unit (Y3/8n4), gear range
• Status of ECO start/stop function button (N72s9) (with code 446 (Touchpad only)) on lower control panel (N72) (with code 446 (Touchpad only)), via UBF-LIN (LIN A3), Touchpad (A105) (with code 446 (Touchpad only)), telematics CAN (CAN A), head unit (A26/17), user interface CAN (CAN HMI), electronic ignition lock control unit, chassis FlexRay (Flex E), powertrain control unit (N127) and via the drive train CAN to the ME-SFI [ME] control unit
• Status of ECO start/stop function button (A40/9s9) (with code 448 (Touchpad)) on Audio/COMAND control panel (A40/9) (with code 448 (Touchpad)), via telematics CAN, COMAND controller unit (A40/3) (up to model year 2018) or head unit (from model year 2018), user interface CAN, electronic ignition lock control unit, chassis FlexRay, powertrain control unit and via the drive train CAN to the ME-SFI [ME] control unit

Engine management Start-Stop function, function sequence 

The ECO start/stop function consists of the following partial functions:

• Function sequence for automatic engine stop 
• Function sequence for automatic engine start 

The automatic engine stop in hybrid vehicles is equivalent to electrical driving.

Additional function requirements for an automatic engine stop 

• Hybrid drive system "READY"
• Internal combustion engine running
• vehicle speed < 160 km/h
• transmission oil temperature > 0°C

Function sequence for automatic engine stop 

The ME-SFI [ME] control unit makes the request via the drive train CAN to the fully integrated transmission control unit for actuation of the wet clutch in order to disconnect the internal combustion engine from the drive. The fully integrated transmission control unit transmits appropriate feedback over the opened wet clutch to the ME-SFI [ME] control unit.

The internal combustion engine is switched off by the ME-SFI [ME] control unit if all releases and system conditions of the systems participating in the function are fulfilled.

Additional function requirements for an automatic engine start 

• Hybrid drive system "READY"
• Internal combustion engine OFF

Function sequence for automatic engine start 

An automatic engine start is initiated if the vehicle needs energy for the traction which cannot be delivered purely electrically or changes in system conditions require starting of the internal combustion engine.

Start of the internal combustion engine takes place according to the specifications of the aggregate coordinator interface in the ME-SFI [ME] control unit:

• over the electrical machine (A79/1) (for vehicle standstill), to the power electronics control unit (N129/1) requested via the hybrid CAN (CAN L)

or

• via the starter (M1) (e.g. in electrical operation)

In electrical operation, starting with an opened wet clutch always occurs first over the starter up to a certain rotational speed of the internal combustion engine. The ME-SFI [ME] control unit subsequently requests actuation of the wet clutch via the drive train CAN from the fully integrated transmission control unit in order to connect the internal combustion engine with the transmission.

After receiving the respective feedback over the closed wet clutch, the ME-SFI [ME] control unit requests actuation of the electrical machine via the hybrid CAN from the power electronics control unit in order to start the internal combustion engine.

The automatic engine start is performed via the electrical machine, preferably when the vehicle is stationary. The internal combustion engine is started over the starter in a vehicle standstill condition if the charge level of the high-voltage battery (A100g1) is not adequate.

The ME-SFI [ME] control unit actuates the following assembly parts to start the internal combustion engine:

• Starter
• Ignition coils (T1)
• Fuel injectors (Y76)
• Fuel pump (M3), directly and via the drive train CAN over the FSCU (N118)

	Electrical function schematic for engine timing, start/stop		PE07.10-P-2722-97SEC
	Overview of system components for gasoline injection and ignition system with direct injection	Engine 276.9 in model 222	GF07.70-P-9998MMK
		Engine 276.8 in model 222.163/173	GF07.70-P-9998MMT