PRE-RELEASE
Boost pressure control
| Boost pressure control |
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Desired value calculation
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Current boost pressure and atmospheric pressure
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Boost pressure control
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| Desired value calculation |
The desired value calculation uses the parameters
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Engine RPM
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Desired fuel quantity
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Atmospheric pressure from the atmospheric pressure sensor
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To determine the desired value for the boost pressure, a stored value is taken that is dependent on the engine speed and the injected fuel quantity. This value is corrected for the air pressure.
| Current boost pressure and current atmospheric pressure |
The boost pressure is measured by the manifold absolute pressure sensor (407/603) in the intake manifold and filtered before being passed on to the control module.
The atmospheric pressure is measured by the atmospheric pressure sensor (539) on the left of the radiator.
| Boost pressure control |
The timing ratio is regulated when the following conditions are met:
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No system faults (DTC) related to the mass air flow sensor, EGR or turbocharger control
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Injected fuel quantity exceeds 2.5 mg/combustion
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The desired boost pressure value is converted to a timing ratio using pre-programmed tables. The timing ratio is then conveyed to the amplifier control, where the signal is amplified and compensated for the battery voltage, see table.
The diagnostic tool displays the boost pressure control valve value as a percentage. 65% PWM means that the boost pressure control valve is closed.
When a DTC related to boost pressure control is generated, PSG 16 limits engine torque.
