Pulse Width Modulated EGR System
This type of EGR system is controlled entirely by the ECM. The ECM controls the flow rate through a solenoid. The solenoid is pulsed at a rate up to 32 times per second. The ECM uses a ported vacuum signal to determine the flow rate signal to the solenoid. You'll note that in Fig 1 : Cutaway View of Pulse Width Modulated EGR Valve, it is the same as the Vacuum Modulated EGR Valve.