Chrysler Conquest 1988 Service Manual page 683

EMISSION CONTROL SYSTEMS
- General Information
25-11
Exhaust Gas Recirculation (EGR) system is designed to reduce
oxides of nitrogen in the vehicle exhaust.
In this system, the exhaust gas is partially recirculated from an
exhaust port at the cylinder head into a port located at the
intake manifold while the EGR flow is controlled by an EGR
control valve, an EGR control solenoid valve, and an ECU.
Contents of Control
As the engine is warmed up and the engine coolant tempera-
ture rises [to 55°C (131°F) or higher] but the engine speed is
low (approximately 3,500 rpm or less), the ECU turns off the
power transistor so as to shut off current flowing to the EGR ~-
control solenoid valve. As a result, the mixing body E port
vacuum acts on the EGR valve to open it.
At this time, the EGR flow rate is controlled by the E port
vacuum. Namely during idling or wide throttle valve opening
operation when the E port vacuum is low, the EGR valve is
closed by the spring force so that EGR gas does not flow.
NOTE
During idling, the EGR gas is shut off to ensure stable idling
operation.