the ecu 36 using the information from the signal the ecu 36 determines whether the valve 50 needs to change position or be maintained the desired position of the valve 50 is achieved by the ecu 36 adjusting the control signal to the actuator 38 it should be noted that the characteristic measured is not necessarily limited to pressure the characteristic could also be mass flow rate volumetric flow rate temperature air particulate content contamination density or any other type of characteristic which can be used to provide an indication of gas flow the sensor 62 could be any type of sensor used to measure the specific characteristics listed above on the first side 58 and the second side 60 of the valve seat 56 the pressure drop can be used to calculate the amount of exhaust gas flowing through the effective orifice 64 the sensor 62 will then provide a signal to the ecu 36 the ecu 36 will then determine if the valve 50 position and control signal must change to achieve the desired exhaust gas flow through egr valve 30 in this embodiment ecu 36 is programmed with a map of engine 12 operating conditions or a set of predetermined operating conditions for the valve 50 and a desired exhaust gas flow for each condition there.