The EGR system recirculates a part of the exhaust gas back into the inlet manifold, which results in reducing NOx emissions. Higher maneuverability and emission reduction are both realized by controlling the EGR system. The EGR valve is equipped with a microprocessor. The internal microprocessor controls the EGR motor according to the commands from the ECM. The ECM calculates the desired EGR position based on the driving condition of the engine, and sends it to the EGR valve via CAN. The EGR valve lift amount is calculated by the microprocessor inside the EGR valve, and is sent to the ECM via CAN. The EGR is activated when the specified conditions of engine speed, engine coolant temperature, intake air temperature, and barometric pressure are met. Then, the valve opening position is calculated based on engine speed and the desired fuel injection quantity. The motor drive duty is determined based on this valve opening position, and the valve is driven according to the motor drive duty. The intake throttle valve appropriately adjusts the inlet manifold vacuum and closes when the EGR is activated.
EGR control operating conditions