The electronically controlled EGR system consists of an EGR valve, engine-ECU and sensors. The EGR valve aims at reducing the amount of NOx (nitric oxide) discharge that increases with the rise in the exhaust gas temperature. Also, the EGR cooler bypass system is employed. By blocking the exhaust gas flow not to pass through the EGR cooler at the engine cold state, HC (hydrocarbon) emissions are reduced. Thus, the engine-ECU optimally controls the exhaust gas temperature in accordance with the operating conditions of the engine. To further improve the exhaust gas reduction performance, the system provides the engine-ECU feedback on the EGR valve opening. Thus, it effects EGR control to optimize the operating conditions of the engine.
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