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

Claim 0:
1. A method for diagnosing an abnormality of an internal combustion engine, comprising:
detecting, during a predetermined operation state in which an opening degree of a first intake throttle valve for controlling an intake air amount of the internal combustion engine is fixed, a first intake air amount when an opening degree of a second intake throttle valve positioned on an upstream side of the first intake throttle valve is set to a predetermined first valve opening degree and a second intake air amount 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, by an intake air amount detecting sensor positioned more on an upstream side than the second intake throttle valve; and
diagnosing a presence of an abnormality in 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, on a basis of the first intake air amount and the second intake air amount,
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.