EGR Control Solenoid: Description and Operation

The dual EGR solenoid valve assembly consists of two dithering solenoid valves. The first is a vacuum valve which supplies vacuum to the sonic EGR valve when energized. The second is a vent valve which vents the EGR valve to the atmosphere when de-energized. Both solenoid valves receive variable duty cycle signals from the ECA according to EGR requirements. A restrictor is added in the vacuum valve inlet port to reduce its flow compared to that of the vent valve so that when vacuum valve sticks open, the vent valve can immediately vent the vacuum valve flow without affecting the devices being controlled.