Method and system for valve movement detection

A fuel injection method for a mechanically-actuated electronically-controlled fuel injector having a spill valve and a control valve, comprising:

• applying a chopped spill valve current to close the spill valve according to a first method;
• applying a control valve current to cause a control valve member of the control valve to move from a first position to a second position;
• stopping the application of the control valve current to cause the control valve member to return to the first position from the second position;
• switching the chopped spill valve current to a non-chopped spill valve current to maintain the spill valve closed, according to a second method;
• and
• detecting a timing of the return of the control valve member to the first position while applying the non-chopped spill valve current.

A fuel injection control system, comprising:

• at least one power source;
• a fuel injector including a spill valve including a spill valve solenoid, and a control valve including a control valve solenoid;
• and
• a controller configured to:
• apply a first method current to the spill valve solenoid according to a first method;
• apply a control valve current to open a control valve;
• discontinue the application of the control valve current to the control valve solenoid to cause the control valve to close;
• apply a second method current to hold the spill valve closed according to a second method;
• and
• detect a timing of a closing of the control valve while applying the second method current according to the second method, wherein the second method has a lower cross-talk potential than the first method.