| 摘要 |
PROBLEM TO BE SOLVED: To diagnose abnormality of an intake air flow control valve accurately. SOLUTION: A first branch passage 25 and a second branch passage 26 are connected with a combustion chamber 12 provided in each of cylinders #1 to #4 of an internal combustion engine 10 via a pair of intake ports 22a, 22b. A swirl valve 30 is provided in the first branch passage 25 of each of the cylinders #1 to #4. A pressure sensor 48 detects internal pressure at a position 25a upstream of the swirl valve 30 in the first branch passage 25 of the cylinder #4. An electronic control unit 40 evaluates pulsation of the internal pressure, judges whether the evaluation result conforms to an opening command to the swirl valve 30 and diagnoses abnormality thereof.
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