EGR System: Operation

EGR system is controlled by EGR valve. When valve is open, exhaust gas enters manifold passages. When closed, no gas is allowed to enter intake manifold. Vacuum signals control opening and closing of EGR valve.

Light Duty Emissions EGR systems use a back pressure transducer to aid in controlling exhaust gas recirculation. This unit senses exhaust gas back pressure and modulates vacuum signal to EGR valve in response to amount of back pressure. Back pressure is used to provide information on engine operation modes. The back pressure transducer is integral with EGR valve.