Abnormality detection apparatus for intake system of internal combustion engine

An abnormality detecting apparatus for an intake system of an internal combustion engine, which detects an abnormality of said intake system, said intake system having a throttle valve, a bypass passage bypassing said throttle valve, and an idling control valve for controlling the amount of air supplied through the bypass passage to said engine, said abnormality detecting apparatus comprising:

• first module for calculating a total intake air amount supplied to said engine;
• second module for calculating an amount of intake air supplied through said bypass passage based on a valve opening control quantity for said idling control valve;
• third module for calculating a parameter indicative of a leak air amount of said intake system according to the result of a comparison between the total intake air amount calculated by said first module and the amount of intake air calculated by said second module;
• and
• abnormality determining module for determining that said intake system is abnormal when the parameter calculated by said third module is greater than a determination threshold in an engine operating condition where said throttle valve is substantially fully closed.

An abnormality detecting method for an intake system of an internal combustion engine, in which an abnormality of said intake system is detected, said intake system having a throttle valve, a bypass passage bypassing said throttle valve, and an idling control valve for controlling the amount of air supplied through the bypass passage to said engine, said abnormality detecting method comprising the steps of:

• a) calculating a total intake air amount supplied to said engine;
• b) calculating an amount of intake air supplied through said bypass passage based on a valve opening control quantity for said idling control valve;
• c) calculating a parameter indicative of a leak air amount of said intake system according to the result of a comparison between the total intake air amount calculated at step a) and the amount of intake air calculated at step b);
• and
• d) determining that said intake system is abnormal when the parameter calculated at step c) is greater than a determination threshold in an engine operating condition where said throttle valve is substantially fully closed.