Exhaust Gas Recirculation: Description and Operation

EGR System:

PURPOSE
Exhaust gas recirculation (EGR) systems reduce NOx emissions by lowering combustion chamber temperatures. This achieved by recirculating part of the exhaust gas into the cylinders.

OPERATION
The EGR valve opens in response to engine driving conditions to direct part of the exhaust gas into the cylinders through the intake manifold. The vacuum signal for controlling EGR valve operation is picked up from a port on the carburetor. The EFC control unit regulates a solenoid valve that switches vacuum to the EGR valve ON and OFF depending on driving conditions.

CONSTRUCTION
The system consists of EGR valve, EGR control solenoid, and necessary hoses and piping.