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

Engine 178.9 In Model 190 

Function requirements, general 

IMPORTANT The ME-SFI [ME] control unit (N3/10) detects the engine running via the evaluation of the crankshaft Hall sensor signals (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 control unit evaluates the following variables to implement the function:

The ME-SFI [ME] control unit evaluates the input signals and actuates the following components:

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 calculates 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 drivetrain 

Vibrations transmitted through the drivetrain 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 drawn on here for the detection of smooth wheel running.

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 detects a combustion failure, the injection of the relevant cylinder is disabled after a certain number of misfires.

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 

G16681202Courtesy of MERCEDES-BENZ USA

Active engine and transmission mount (with code 466 (Active engine mount)) 

The following component parts are installed for enhancing comfort and vehicle dynamics:

A metalized fluid on the inside of the active engine and transmission mounts reacts with a change in viscosity on the magnetic field generated by the following component parts:

This in turn influences the rigidity of the active engine and transmission mounts. When the engine is idling with soft engine and transmission mounts, this provides greater comfort by reducing the transmission of vibrations from the drivetrain to the body. When the vehicle is being driven, stiffening of the active transmission mounts results in more precise steering and increased vehicle dynamics.

The computation of the specified status of the active engine and transmission mounts takes place by the AMG suspension control unit (N3/43). The AMG suspension control unit evaluates the following variables to implement the function:

The AMG suspension control unit transmits the following signals of the pressure sensors and requirements via the AMG CAN (CAN AMG) to the active engine mount control unit to implement the function:

The active engine mount control unit actuates the coils of the active engine mount.

The AMG suspension control unit transmits the following signals and requirements via the AMG CAN to the active transmission mount control unit to implement the function:

The active transmission mount control unit actuates the coils of the active transmission mount.

  Electrical function schematic for smooth running control   PE07.10-P-2711-97HBA
  Overview of system components for gasoline injection and ignition system with direct injection   GF07.70-P-9998MNB 
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