| 摘要 |
PROBLEM TO BE SOLVED: To determine an abnormality in a wide operation range and identify the cause for the abnormality by utilizing a supercharging pressure and an actual air-fuel ratio. SOLUTION: An abnormality diagnosis device includes a supercharger, an exhaust air reflux control valve which opens and closes an exhaust air reflux passageway that connects the exhaust air passageway of an internal combustion engine and an air inlet passageway on the downstream of a throttle, a supercharging pressure sensor which detects the supercharging pressure on the downstream of the throttle, and an air-fuel ratio sensor which detects the actual air-fuel ratio of the exhaust air. It is determined as abnormal when the divergence ΔA/F between a target air-fuel ratio and the actual air-fuel ratio becomes a specific value α or above while the air-fuel ratio feedback of the exhaust air is controlled towards the target air-fuel ratio based on the actual air-fuel ratio (S11). In case of positive pressure it is transferred into a negative pressure state (S12-S14) and the cause for the abnormality is identified based on the deviation direction of the actual air-fuel ratio to the target air-fuel ratio in the positive pressure state and the deviation direction of the actual air-fuel ratio in the negative pressure state (steps S15-S21). COPYRIGHT: (C)2011,JPO&INPIT
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