EGR System: Description

The Exhaust Gas Recirculation (EGR) system allows small quantities of pre-burned (non-combustible) exhaust gas to enter the intake manifold where it is mixed with the incoming air/fuel charge. By absorbing combustion heat and displacing air and fuel (which would produce additional heat), these gases serve to lower peak combustion chamber temperatures and reduce the formation of Oxides of Nitrogen (NOx) during the combustion process.

The EGR system consists of an EGR valve, EGR vacuum modulator valve, vacuum delay valve, 2 EGR vacuum solenoid valves, coolant temperature switch, and the ECA. California vehicles also are equipped with an EGR Valve Position (EVP) sensor.