Abstract: An engine with a valve actuator to extend duration of a valve event and method of controlling an engine with such an actuator are disclosed. The actuator may include an actuator cylinder with an actuator piston. The actuator contains an electrorheological fluid. A magnetic flux may be applied the electrorheological fluid to prevent or slow movement of the actuator piston and change valve movement with respect to its regular, cyclical operation provide for with a cam. A biasing means is connected with the actuator piston to allow positioning of the valve actuator in an existing engine design.