Control device and method for a diesel engine

A low NOx combustion mode is executed in which the fuel injection timing IT is greatly advanced to 36 DEG BTDC as compared with a normal value of roughly 10 DEG BTDC. At this fuel injection timing IT, the smoke emission amount is suppressed below an extremely low value, even if the EGR ratio Regr is increased to about 56%, and the NOx emission amount is suppressed owing to a large amount of EGR, so that the smoke and NOx can be reduced at the same time.