Patent attributes
When the opening angle of an intake control valve is limited to a given opening angle by fuel cut, an EGR apparatus is activated, and a malfunction of the EGR apparatus is diagnosed on the basis of a change in intake manifold pressure before and after the activation of the EGR apparatus. When the control for reducing the intake-manifold negative pressure is not implemented, the change of the intake manifold pressure is corrected with a changing amount of first reference intake pressure (P(Ne)) changed by engine speed Ne. When the control for reducing the intake manifold genitive pressure is implemented, the change of the intake manifold pressure is corrected with a changing amount of second reference intake pressure (PL(Ne)) changed by engine speed Ne.
