realized with other types of actuator it has already been stated above that the controlled variable of the actuator is preferably the electrical energy stored in the actuator which for piezoactuators determines the stroke of the valve pin of the injection valve the invention is however not restricted to energy stored in the actuator in respect of the controlled variable for example other controlled variables can also determine the stroke of the valve pin with other actuator types in the exemplary embodiment the readjustment of the pilot control characteristic does not occur continuously but only on demand i e if the pilot control characteristic no longer reflects the actual system behavior sufficiently accurately the pilot control characteristic is therefore readjusted during operation of the injection system preferably only temporarily and or only individually with a demand controlled readjustment of the pilot control characteristic the need for control can be recognized from the fact that the dynamic control deviation occurring during a target value jump exceeds a predetermined maximum value as regards its amount the axis section of the pilot control characteristic is therefore readjusted only if the dynamic control deviation occurring for a target value jump exceeds the predetermined maximum value in another embodiment on the other hand the ambient conditions of the injection system are checked to see whether they have changed with the pilot control characteristic only being readjusted if the ambient conditions have changed to a specific extent.