Patent ID: 6962145

Claim:
A failure detection apparatus for an internal combustion engine, comprising: fresh air quantity detecting means arranged in an intake system of the engine, for detecting a quantity of fresh air introduced into a combustion chamber of the engine; fresh air quantity reference value setting means for setting a reference value for the fresh air quantity in accordance with an operating state of the engine; failure detecting means for detecting abnormality of said fresh air quantity detecting means, based on a result of comparison between the fresh air quantity detected by said fresh air quantity detecting means and the reference value set by said fresh air quantity reference value setting means; exhaust flow rate adjusting means arranged in at least one of the intake system and exhaust system of the engine, for adjusting an exhaust flow rate; target adjustment setting means for setting a target adjustment amount for said exhaust flow rate adjusting means in accordance with the operating state of the engine such that an air-fuel ratio or excess air ratio of the exhaust system becomes equal to a predetermined value corresponding to the operating state; and exhaust flow rate control means for controlling said exhaust flow rate adjusting means in accordance with the target adjustment amount set by said target adjustment setting means, wherein said fresh air quantity reference value setting means sets the reference value in accordance with not only the operating state of the engine but also the target adjustment amount set for said exhaust flow rate adjusting means by said target adjustment setting means.