Smooth running control, function - GF07.10-P-1011OGG

ENGINES 642.8 in MODEL 164.1 as of model year 2009/YoM 08 model refinement package 

ENGINES 642.8 in MODEL 164.8, 251.1 as of model year 2009/YoM 08 

ENGINES 642.8 in MODEL 251.0/1 as of model year 2011/YoM 10 model refinement package 

Function requirements for smooth running control, general points 

• Circuit 87 ON (engine control ON)
• Engine running

Smooth running control, general points 

Smooth running control reduces any rough running in the engine RPM range from 750 to 2600 RPM.

For smooth running evaluation, the CDI control unit (N3/9) reads in the following sensors and signals:

• Hot film mass air flow sensor (B2/6), engine load
• Hot film mass air flow sensor (B2/7), engine load
• Coolant temperature sensor (/)B11/4
• Accelerator pedal sensor (B37), accelerator pedal position
• Crankshaft Hall sensor (B70), engine speed
• Instrument cluster (A1), fuel level via the engine compartment CAN (CAN C)
• ESP control unit (N47-5), wheel speed signal via the engine compartment CAN

Function sequence for smooth running control 

The function sequence is described in the following steps:

• Function sequence for combustion misfire detection 
• Function sequence for factors for smooth running control 

Function sequence for combustion misfire detection 

To do this the CDI control unit (N3/9) reads in the signal from the crankshaft Hall sensor and evaluates it for uniformity. If lack of uniformity occurs in the crankshaft Hall sensor signal, the CDI control unit corrects the fuel pressure in the rails via the pressure regulating valve (Y74) and the quantity control valve (Y94) and the injection time via actuation of fuel injectors (Y76).

The fuel pressure in the rails and the injection timing of the fuel injectors combine to produce a specific injection quantity.

Function sequence for factors for smooth running control 

The following factors affect smooth running control:

• Recognition of an uneven road surface 
• Fuel reserve signal 
• Sensor adaptation 

Recognition of an uneven road surface 

Vibrations transmitted through the drive train may have a negative effect on engine running at certain engine speeds and load conditions. Therefore, the tolerance range for smooth running analysis is increased on poor road surfaces ("wash board").

The CDI control unit receives the wheel speed signal (for detection of even wheel rotation) via the engine compartment CAN from the ESP control unit.

Fuel reserve signal 

The SAM control unit at the rear (N10/8) evaluates the signals of the fuel level sensor, tank half on the left and right (B4/1, B4/2) and gives out a corresponding signal via the interior CAN (CAN B) to the instrument cluster (A1).

The CDI control unit receives information about the fuel level from the instrument cluster via the engine compartment CAN.

Sensor adaptation 

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

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

The CDI control unit stores the smooth operation characteristics of the engine during a deceleration phase (accelerator pedal not operated) when uniform smooth operation is present. These are required as a comparison parameter for misfire detection.

The tolerance range for smooth running evaluation is preset in the CDI control unit and can be adapted using the Diagnosis Assistance System (DAS) if necessary.

	Electrical function schematic for smooth running control	Model 164	PE07.10-P-2711-97MAA
		Model 251	PE07.10-P-2711-97RAA
	Component description for instrument cluster	A1	GF54.30-P-6000GM
	Component description for CDI control unit	N3/9	GF07.16-P-6000OGU
	Component description for rear SAM control unit	N10/8	GF54.21-P-7030GM
	Component description for ESP control unit	N47-5	GF42.45-P-5118GM