Patent ID: 7953529

Claim:
An apparatus for determining an abnormality of an intake air system of an internal-combustion engine having a variable valve actuation mechanism for continuously adjusting at least a lift amount of an intake valve to control an intake air amount and a throttle valve for keeping a gauge pressure in an intake manifold at a predetermined desired gauge pressure, the apparatus comprising: means for determining a throttle opening area based on a current intake air amount; means for performing a feedback correction on the throttle opening area, the feedback correction including determining a correction amount of the throttle opening area such that the gauge pressure in the intake manifold converges to the desired gauge pressure and adding the correction amount to the throttle opening area; means for performing a feedback control for an air-fuel ratio, the feedback control including determining a correction amount of the air-fuel ratio based on a detection value of an air-fuel ratio detecting means that is provided in an exhaust manifold; and means for determining an abnormality of the intake air system during an idling operation based on the correction amount of the throttle opening area and the correction amount of the air-fuel ratio.