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Smooth Running Control, Function - GF07.10-P-1011MNA

Engine 177.9 in model 205, 253 

Engine 177.9 in model 213 

up to model year 2021 

Function requirements, general 

IMPORTANT The ME-SFI [ME] control unit (N3/10) detects the engine running by evaluating the signals of the crankshaft Hall sensor (B70). The ME-SFI [ME] control unit directly reads in the signals of the crankshaft Hall sensor.

Smooth running control, general points 

Smooth running control ensures that the engine is also smooth in fuel saving lean-burn operation in partial-load range and turns evenly. In this way the tangible rough running should be avoided for the driver. Also the CATs are protected from thermal overloading if there are combustion misfires.

The ME-SFI [ME] control unit (N3/10) reads in signals from the following components for controlling smooth running:

The ME-SFI [ME] control unit also takes the vehicle speed into account. The ME-SFI [ME] control unit calculates the vehicle speed from the wheel speeds. The Electronic Stability Program control unit (N30/4) transmits the wheel speeds via the chassis FlexRay (Flex E), the powertrain control unit (N127) and the drive train CAN (CAN C1) to the ME-SFI [ME] control unit.

The following factors affect smooth running control:

Engine speed and engine load 

Using the engine speed and engine load, the ME-SFI [ME] control unit computes a reference value for the time between two combustions.

Coolant temperature 

For a cold engine, more combustion misfires are permissible than for an engine at operating temperature.

Vibration transmitted via the drive train 

Vibrations transmitted through the drive train may have a negative effect on evaluation of the engine running at certain engine speeds and load conditions. Therefore, the tolerance range for smooth running control is increased on poor road surfaces. The wheel speed is included here for the detection of an even wheel arch.

Model 205, 213 with code 466 (Active engine mount) 

For improving ride comfort and vehicle dynamics, the following components are installed on the engine that support the engine on the integral carrier:

The engine mounts reduce the transmission of vibration from the engine to the body in neutral. While driving, the engine mounts improve the handling characteristics.

The engine mounts consist of:

A metalized fluid inside the engine mount reacts to the magnetic field generated by the active engine mount coil by changing its viscosity. This in turn influences the rigidity of the engine mounts.

The AMG suspension control unit (N3/43) calculates the specified status of the engine mounts. A number of variables are evaluated here. The ME-SFI [ME] control unit sends the "Engine running" signal via the drive train CAN to the AMG suspension control unit. The AMG suspension control unit evaluates the variables, calculates the specified status and sends the corresponding requests via AMG CAN (CAN AMG) to the active engine mount control unit (N3/42). The active engine mount control unit then actuates the coils of the active engine mount.

The active engine mount pressure sensors record the pressure ratios in the engine mounts. The active engine mount control unit reads in the signals of the pressure sensors and transmits these via the AMG CAN to the AMG suspension control unit. The AMG suspension control unit calculates the actual status of the engine mounts from the pressure sensor signals. The AMG suspension control unit transmit the status of the active engine mount control via drive train CAN to the ME-SFI [ME] control unit.

Synchronization of injection and firing order 

Cylinder detection is required for fault storage and evaluation using the signals from the crankshaft Hall sensor and the intake camshaft Hall sensors or the exhaust camshaft Hall sensors.

Sensor adaptation 

The tolerance range for smooth running control is reduced after successful adaptation of the crankshaft Hall sensor.

In this way, the smooth running control can be adapted to the specific smooth running characteristics of the engine.

The ME-SFI [ME] control unit saves the smooth operation characteristics of the engine during a deceleration mode (accelerator pedal not operated) when uniform smooth operation is present. These are required as a comparison parameter for misfire detection.

Combustion misfirings 

For the smooth running control, the signal from the crankshaft Hall sensor is evaluated using a comprehensive mathematical procedure, to check for precise uniformity of timing between individual combustions. Each individual combustion must generate a characteristic acceleration at the sensor rotor.

If there are combustion misfires, the sensor rotor turns up to the next ignition somewhat slower (torque fluctuation).

If the smooth running control in the ME-SFI [ME] control unit detects a combustion misfire, the relevant cylinder is disabled after a certain number of combustion misfires have occurred.

However, no more than three cylinders are disabled simultaneously. The total number of combustion misfires detected is stored in the fault memory and subdivided into:

What is detected is combustion misfiring caused by:

Smooth running signal 

G13770173Courtesy of MERCEDES-BENZ USA
  Electrical function schematic for smooth running control Engine 177.9 in model 205, 253 PE07.10-P-2711-97FBD
    Engine 177.9 in model 213 up to model year 2021 PE07.10-P-2711-97DBG
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    Engine 177.9 in model 213 up to model year 2021 GF07.70-P-9998MNE
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