Engine timing start-stop function - GF07.10-P-1041OGA
ENGINE 642.8 in MODEL 207, 212, 218 as of model year 2014
The "Engine management, start/stop function" subfunction is examined from the point of view of the engine management.
Information for partial function "Energy management, start/stop function" is documented in the function description "Energy management function".
Function requirements for start/stop function, general points
- Engine runs at its operating temperature (coolant temperature: T > 60°C < 115°C)
- Speed of 15 km/h exceeded once during forward travel
- Engine hood closed
- Gear range "N"
- System diagnosis completed
Engine management start-stop function, general
With a stationary vehicle, the start/stop function switches the engine off automatically and starts it again as soon as the driver wishes to drive off. The fuel consumption and thus the exhaust emissions are reduced by cutting out of the engine with the vehicle at a standstill.
The CDI control unit (N3/9) permanently performs a system diagnosis and assesses the function requirements for the ECO start/stop function.
It is still possible to stop and start the engine in the conventional way.
The front SAM control unit with fuse and relay module (N10/1) also checks the function of all involved components and transmits the status to the ME-SFI [ME] control unit via the chassis CAN 1 (CAN E1) to the CDI control unit. If the function requirements are fulfilled, the driver is notified of ECO start/stop function readiness by the "ECO" symbol in the multifunction display (A1p13) in IC (A1).
The messages for actuation of the multifunction display are received by the IC via chassis CAN 2 (CAN E2) are routed from the front SAM control unit with fuse and relay module, which receives the message via the chassis CAN 1 by the CDI control unit.
For the ECO start-stop function the CDI control unit reads in the following sensors and signals:
- Coolant temperature sensor (B11/4) (model 207, 212), coolant temperature sensor (B11/4) (model 218)
- Accelerator pedal sensor (B37), accelerator pedal actuation
- Fuel temperature sensor (B50)
- Crankshaft Hall sensor (B70), engine rpm
- Supplemental Restraint System control unit (N210) via the chassis CAN 1
- Signal that engine hood is closed
- Indirect crash signal
- Status of driver seat belt
- SRS control unit, direct crash signal
- Front SAM control unit with fuse and relay module
- A/C status
- Engine stop prohibition
- Engine start request
- Contact switch signal at the front left
- ECO start/stop function button (N721s50) status
- Signal "Engine hood closed" (with code (551) Anti-theft alarm system (ATA [EDW])
Electronic Stability Program control unit (N30/4) (except code (233) DISTRONIC PLUS) or Electronic Stability Program Premium control unit (N30/7) (for code (233) DISTRONIC PLUS) via chassis CAN 1
- Brake actuation
- Vehicle speed
- Wheel speed
- Engine start request
- Engine stop release
- Engine stop prohibition
- Driving Assistance Package (signal characteristic for model 207, 212, 218 as of model year 2015), via the radar sensors control unit (N62/1) (with code 23P (Driving Assistance Package) via the chassis suspension FlexRay (Flex-E), to the chassis gateway control unit (N93/7) (with code (23P) (Driving Assistance Package) via the chassis CAN 1 to the CDI control unit.
- Fuel system control unit (N118), fuel pressure via the drive train CAN (CAN C)
- Steering column tube module control unit (N80), steering wheel angle and steering wheel angle speed via the chassis CAN 1
- Fully integrated transmission controller unit (Y38) (with code (427) 7-speed A/T or code (421) 9-speed automatic transmission), gear range via the drive train CAN
- DISTRONIC PLUS or Active Blind Spot Assist, (signal characteristtc for model 218 as of 01.03.13 to model year 2015) over video and radar sensor system control unit (N62/2) (with code (233) DISTRONIC PLUS) or with code (237) Active Blind Spot Assist or with code (238) Active Lane Keeping Assist) via chassis CAN 1 to CDI control unit.
Engine management Start-Stop function, function sequence
The start/stop function consists of the following partial functions:
- Function sequence for engine stop
- Function sequence for engine start
- Function sequence for forced engine start
Function sequence for engine stop
The engine is switched off by the CDI control unit if all of the following function requirements are fulfilled:
- Indicator lamp on the ECO start/stop function button lights up
- Vehicle speed = 0 km/h
- Coolant temperature >60°C and <115°C
- Transmission oil temperature > 10°C and < 120°C
- Engine oil temperature in the specified value range
- Engine rpm in specified value range
- Gear range "N"
- Accelerator not operated
- Service brake actuated up to standstill of the vehicle
- Adequate vacuum in the brake booster
- No control intervention function by brake assistance and distance control system
- Accelerator not operated
- Service brake actuated up to standstill of the vehicle
- Adequate vacuum in the brake booster
- No control intervention function by brake assistance and distance control system
- Engine hood closed
- No crash signal
- Steering wheel angle a maximum of 210°
- Steering wheel angular velocity in the specified value range
- Outside temperature in the range -10 to 40°C
- Condition of the on-board electrical system OK
- Driver door closed
- Driver seat belt applied
- Interior temperature regulated
After an automatic engine stop a maximum of three automatic starts are permitted without exceeding the speed threshold of 8 km/h. After the fourth engine start, the vehicle must exceed a speed of 8 km/h for the engine to be stopped again.
Function sequence for engine start
The engine is started automatically for actuation of the accelerator pedal.
The CDI control unit actuates the circuit 50 starter relay (N10/1kM) by means of a ground signal.
The power contact on the relay closes and the starter solenoid switch (M1) is supplied at "circuit 50" with a voltage from "circuit 30".
The fuel system control unit receives the CAN signal "Fuel specified pressure" from the CDI control unit via the drive train CAN and actuates the fuel pump (M3) with a pulse width modulated signal accordingly.
Function sequence for forced engine start
The forced engine start subfunction is available as a protection function. Here the engine is force started autonomously (without any action taken by the driver) by the CDI control unit if one of the following function requirements occurs:
- Condition of the on-board electrical system not OK
- Coolant temperature >115°C
- Exceeding of the engine stop period of a maximum of 3 minutes
- Change in the status of the A/C
- Brake assistance and distance control system performing control intervention
- A brake application cannot be safely completed once initiated
- The vacuum in the brake booster is not adequate
- Driver absence detected
- Change of the steering wheel angle by more than 8°
- Vehicle speed > 2 km/h
- Communication error of ECO start/stop function with one of the systems involved
A maneuvering process is recognized for an engaged gear range "R" and the ECO start/stop function is deactivated.
If the engine is stopped it is force started, and if it is running the engine stop function is suppressed.
The ECO start/stop function is subsequently activated again for an engaged gear range "D" and for exceeding a vehicle speed of 15 km/h.
| Function schematic for start-stop engine timing | ENGINE 642.8 in MODEL 207 as of model year 2014 | PE07.10-P-2722-97EAJ | |
| ENGINE 642.8 in MODEL 212 as of model year 2014 | PE07.10-P-2722-97DAM | ||
| ENGINE 642.8 in MODEL 218 as of model year 2014 | PE07.10-P-2722-97XAE | ||
| Overview of system components for common rail diesel injection (CDI) | GF07.16-P-9997OG |