Exhaust Gas Recirculation: Description and Operation

Typical EGR System Operation:

PURPOSE
The Exhaust Gas Recirculation (EGR) system is an emission reducing system that concentrates primarily on the reduction of oxides of nitrogen (NOx).

OPERATION
The purpose of the EGR system is accomplished by allowing a specified amount of hot exhaust gas to flow from the exhaust manifold into the intake manifold to mix with the incoming air/fuel mixture. This mixture enters the combustion chamber and lowers the peak flame temperature during combustion. This reduction in combustion temperature reduces the possibility of ignition knock and the level of NOx output.