Component description for the boost pressure positioner - GF09.40-P-4020TU

ENGINE 642 as of 1.6.06 in MODEL 211.0/2/6, 219.3 as of 1.6.06

ENGINE 642 in MODEL 164.1/8, 251.0/1 with CODE (494) USA version up to Model Year 8

Shown on model 211.020 with OM 642.920 with code (494) USA version

Fig 1: Locating Boost Pressure Positioner

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Location

The boost pressure positioner is located on the turbocharger.

Task

The boost pressure positioner is actuated by the CDI control unit (N3/9) and changes the position of guide vanes in the turbocharger and thus the boost pressure. Boost pressure control of the turbocharger improves the torque characteristics in full-load operation and gas cycle under partial-load conditions. The specified value for the boost pressure depends on the following influencing factors:

Engine speed
Quantity injected
Coolant temperature
Intake air temperature
Atmospheric pressure

Design

The boost pressure positioner consists of an actuator motor and an electronic unit.

Function

An adjusting shaft is turned via a worm drive which is connected with the guide vanes in the turbocharger.