Dual EGR Control Solenoids
EGR valve flow rate is controlled by two solenoid valves mounted on the left valve cover. Proper control of vacuum needed to operate the EGR valve requires two types of solenoid valves:
- A vent valve, which is normally open; that is, the outlet port is normally connected to the inlet port when the solenoid is not energized.
- A vacuum valve, which is normally open; that is, the outlet port is normally blocked when solenoid is not energized.
Utilizing input from the various sensors, the ECA directs the vacuum and vent solenoids to: (1) Increase EGR flow by applying vacuum to the EGR valve, (2) Maintain the EGR flow by trapping vacuum in the system, and (3) Decrease EGR flow by venting the system to the atmosphere.