Pulse Width Modulated EGR System
The Electronic Control Module (ECM) controls EGR valve operation. The ECM uses information from input sensors to determine correct amount of EGR. See Fig 1 .
This type EGR system is controlled entirely by the ECM. The ECM controls the flow rate by controlling an electrical signal to a solenoid vacuum valve. The ECM controlled vacuum solenoid valve is located in series between vacuum source and EGR valve. The solenoid is pulsed at a rate of up to 32 times per second. The ECM uses a ported vacuum signal to determine the flow rate signal to the solenoid.