EGR Control Valves: Notes

Increased EGR flow (which adversely affects driveability) is required to meet stringent emission standards. The EGR control valves compensate for the EGR system's effect on driveability. The amount of vacuum is controlled by throttle opening. The EGR system increases EGR flow during high load operation and decreases during low load operation. There is no EGR operation at idle or wide open throttle because vacuum level is low.