Basic Charging Pressure

BASIC CHARGING PRESSURE
The basic charging pressure provides the basis for boost pressure control.

The basic charging pressure is adjusted mechanically on the pressure rod between the membrane housing unit and the turbo wastegate.

If the basic charging pressure is too low, the build-up of pressure when the accelerator is depressed is too slow and the engine responds slowly when the throttle is opened quickly.

If the basic charging pressure is too high, negative boost pressure adaptation takes place and the maximum boost pressure cannot be attained. There is also a risk of damage to the engine as sufficiently low pressure is not achieved in knock control.

The basic charging pressure must be 0.40 ± 0.03 bar. After adjustment, the pressure rod must have at least two turns (2 mm) of prestressing (hook on).

The purpose of this is to ensure that the wastegate is completely closed when it is not operating.

On new turbo units the basic charging pressure tends to be at the upper tolerance limit at prestressing of two turns. However, the prestressing must never be less than two turns (2 mm).

When the basic charging pressure is checked, it should be noted that the pressure drops at high engine speeds and rises in the case of low outdoor temperatures.