1. A method of controlling a plunger lift system for a well and adjusting an operational threshold, the plunger lift system having a tubing positioned in a cased well, a plunger in the tubing moveable from the bottom of the tubing to a top of the tubing, a control valve in functional connection with the tubing, a plunger arrival sensor, a tubing pressure sensor, a casing pressure sensor, and a sales line pressure sensor, a controller in operational connection with the control valve and functional connection with the sensors for receiving signals from the sensors, the method comprising the steps of: defining a threshold value for a trigger event the trigger event initiating operation of the control valve by the controller, wherein the trigger event is a rate of change of tubing pressure over time; defining an event-value condition upon which adjustment of the threshold value is adjusted; determining, upon a calling-event, if the event-value condition has been satisfied; and adjusting the threshold value by an adjustment factor upon satisfaction of the event-value condition.