Exhaust Gas Recirculation: Description and Operation

Fig. 31 Single type EGR control valve.:

The EGR valve, Fig. 31 controls the flow of exhaust gas in response to a vacuum control signal from the EGR control solenoid valve. The EGR solenoid valve is controlled by the ECU in response to variations in engine speed and coolant temperature. EGR flow is suspended during idle and full throttle operation.

Fig. 29 EGR system.:

Exhaust gas recirculation, Fig. 29 is used to reduce oxides of nitrogen emissions in the vehicle exhaust. EGR uses partial recirculation of the exhaust gases from a port in the cylinder head to a port in the intake manifold. The EGR valve controls the flow of exhaust gas in response to vacuum signals from the EGR control solenoid valve which is controlled by the ECU. The ECU turns off the EGR control solenoid valve when engine coolant reaches operating temperature and engine speed is less than 3500 rpm. The EGR valve then controls exhaust gas flow in response to 'E' port vacuum.