Method of actuating a butterfly valve arranged in the intake system of an air-compressing fuel-injected internal combustion engine

Method of actuating a throttling element arranged in an intake system of an air-compressing fuel-injected internal combustion engine, said throttling element being of the type which is held in a closing position in low load and speed ranges and held in an opening position in central and high load and speed ranges, a particular opening position of the throttling element being controlled in response to a desired setpoint value for absolute pressure in said air intake system downstream of said throttling element in the direction of airflow, said set point value being determined from an engine load and engine speed-dependent characteristic diagram, said method comprising the steps of:

• determining the engine load and speed at which said engine is operating
• determining from said characteristic diagram a setpoint value corresponding to said engine load and speed;
• correcting said setpoint value in response to atmospheric pressure, the amount of said correction increasing linearly with decreasing atmospheric pressure;
• adjusting the position of said throttling element to an opening position which corresponds to the corrected setpoint value;
• and
• moving said throttling element to a position freeing an entire cross section of said air intake system in response to atmospheric pressure falling below a predetermined limit.