EGR System

The CCC system controls engine emission systems, but is not directly in control of EGR operation. A vacuum signal from the airflow sensor and one from manifold vacuum are compared by the vacuum amplifier to determine the proper amount of EGR. A coolant/sensor valve prevents the vacuum signal from reaching the EGR valve until engine coolant temperature is at least 59-64°F. When the valve opens, vacuum is applied through a 1-second delay valve to ensure smooth EGR valve operation.