Method for controlling the pressure in a vacuum brake booster

A pressure sensor (28) senses the pressure in the vacuum chamber and sends the value to an engine control unit (30) which determines a suction pipe pressure which can be obtained for the air fuel mixture. The engine control unit throttles the air supply according to the air fuel mixture when the suction pipe pressure value which can thereby be achieved is lower than the pressure sensed in the vacuum chamber. The engine control unit only determines the suction pipe pressure which can be achieved when the pressure in the vacuum chamber exceeds a limit value.