Exhaust Gas RECIRCULATION: Operation

The EGR valve, mounted on the exhaust manifold, controls the flow of exhaust gases from the exhaust manifold to the intake manifold. The vacuum signal which controls the EGR valve is taken from a throttle edge tapping which gives no recirculation at idle speed or at full throttle, but gives a varying amount of recirculation between these two extremes depending on vacuum signal and metering profile of the valve. A fuel trap is installed in the vacuum line to the EGR valve to prevent liquid fuel from entering the valve.