Mercury D5FZ-9D473-B EGR Vacuum Control Valve Assembly

For fuel economy purposes designers make adjustments to air/fuel ratios in cruise mode. When people mix lean, the combustion temperatures become high and generate pollutants like NOx. To control NOx during lean cruise modes, the EGR system reintroduces small quantities of exhaust gas into the intake manifold. It is the EGR valve that joins the exhaust system to the intake manifold, which is controlled by a vacuum-activated diaphragm. The F-series and Bronco vehicles have three different types of EGR systems, conventional ported vacuum, integral backpressure valve, and Electronic EGR (EEGR) system. The early non-U.S models used ported vacuum valves while early U.S carbureted models used integral backpressure valves.