Abstract: A fault detector for detecting valve movement of a valve in a fuel injector of an engine system, the valve includes an electromagnetic actuator arranged to move the valve between first and second valve positions, the engine system includes a sensor for sensing a current through the actuator. The detector includes a controller arranged to control the sensor; receive sensor data related to the current through the actuator; analyze the received data for current discontinuities; and output a valve movement signal dependent upon the current discontinuities. The controller is arranged to sense current during a finite sampling window, move the sampling window from a first window position to a later window position for one or more subsequent injection events; determine a new sampling window position on based a valve movement signal output the two preceding windows; and feedback the new sampling window position for a subsequent injection event.

Abstract: A fault detector for detecting valve movement of a valve in a fuel injector of an engine system, the valve comprising an electromagnetic actuator arranged to move the valve between first and second valve positions during a valve cycle, the engine system comprising a sensor for sensing a current through the actuator. The detector comprises a controller arranged to control the sensor; inputs for receiving from the sensor data related to the current through the actuator; a processor arranged to analyze the received data for current discontinuities; and outputs for outputting a valve movement signal in dependence upon the current discontinuities determined by the processor.