Patent ID: 11913400
Assignee: NISSAN MOTOR CO., LTD.
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F  G  Y | IPC F  G

Claim 6:
7. A device for diagnosing an abnormality of an internal combustion engine, comprising:
a first intake throttle valve for controlling an intake air amount of the internal combustion engine;
a second intake throttle valve positioned on an upstream side of the first intake throttle valve;
an intake air amount detecting sensor positioned on an upstream side of the second intake throttle valve and configured to detect the intake air amount;
a blow-by gas recirculation system for blow-by gas treatment connected to a position more on a downstream side than the intake air amount detecting sensor in an intake passage; and
a diagnosis section configured to diagnose an abnormality in the blow-by gas recirculation system, on a basis of a first intake air amount detected by the intake air amount detecting sensor when an opening degree of the second intake throttle valve is set to a predetermined first valve opening degree and a second intake air amount detected by the intake air amount detecting sensor when the opening degree of the second intake throttle valve is set to a predetermined second valve opening degree smaller than the first valve opening degree, during a predetermined operation state in which an opening degree of the first intake throttle valve is fixed,
wherein, during detecting the first intake air amount and the second intake air amount, when the opening degree of the first intake throttle valve is varied, the diagnosis for the blow-by gas recirculation system is stopped.