EGR Valve: Description and Operation

PURPOSE/OPERATION
The EGR Valve allows a measured amount of exhaust gas to be recycled into the intake flow. The valve has a diaphragm with a pintle rod attached to one side of it and a spring pushing on the other side of it (keeping the valve closed). When vacuum is applied to the diaphragm, it overcomes the spring pressure, pulling the pintle rod out of it's seat. This opens the passage, allowing gas recirculation. The amount of recirculation is directly relative to ported vacuum (throttle opening).