Abstract: A method for detecting the opening of a passive pressure control valve, which conducts fuel from a common rail system back to a fuel tank, in which the rail pressure (pCR) is automatically controlled by calculating a correcting variable for acting on the controlled system from a rail pressure control deviation via a pressure controller, and in which, starting from a steady-state rail pressure in normal operation, a load reduction is detected when the rail pressure exceeds a first limit. Opening of the pressure control valve is detected after the first limit is exceeded if a steady-state operating state is subsequently detected again, and if a characteristic of the closed-loop control system deviates significantly from a reference value.

Abstract: In a method for detecting the opening of a passive pressure limiting valve for releasing fuel from a common rail fuel injection system to a tank with a fuel supply including a throttle wherein, based on a stationary rail pressure present during manual operation, a load reduction is detected when the rail pressure exceeds a first limit value and, as a result, a PWM signal for controlling the suction throttle is temporarily increased, the opening of the pressure limiting valve is recognized if, as a result, the rail pressure exceeds a second limit value and increases still further.

Abstract: In a method for detecting the opening of a passive pressure limiting valve for releasing fuel from a common rail fuel injection system to a tank with a fuel supply including a throttle wherein, based on a stationary rail pressure present during manual operation, a load reduction is detected when the rail pressure exceeds a first limit value and, as a result, a PWM signal for controlling the suction throttle is temporarily increased, the opening of the pressure limiting valve is recognized if, as a result, the rail pressure exceeds a second limit value and increases still further.

Abstract: A method for detecting the opening of a passive pressure control valve, which conducts fuel from a common rail system back to a fuel tank, in which the rail pressure (pCR) is automatically controlled by calculating a correcting variable for acting on the controlled system from a rail pressure control deviation via a pressure controller, and in which, starting from a steady-state rail pressure in normal operation, a load reduction is detected when the rail pressure exceeds a first limit. Opening of the pressure control valve is detected after the first limit is exceeded if a steady-state operating state is subsequently detected again, and if a characteristic of the closed-loop control system deviates significantly from a reference value.