Patent ID: 7917310

Claim:
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 comprising: a controller arranged to control the sensor; an input 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; wherein the controller is arranged to enable the sensor during a finite sampling window; to move the sampling window from a first window position for a first injection event to a progressively later window position for one or more subsequent injection events; to determine a new sampling window position on the basis of a valve movement signal output for at least two of the preceding window positions; and to feedback, within the controller, the new sampling window position for a subsequent injection event.