| 摘要 |
When the ratio of the amount of vaporized fuel (purge amount) to be introduced into an intake passage of an engine from a fuel tank through a purge passage pipe, a purge control valve, etc. to the total amount of fuel (total fuel amount) to be supplied to the engine is large, an abnormality determination system acquires, as a parameter Pon, the air-fuel ratio imbalance index value that increases as the difference between the air-fuel ratios of the respective cylinders increases. When the purge amount is small relative to the total fuel amount, the determination system acquires the air-fuel ratio imbalance index value as a parameter Poff. When the difference between the parameters Pon and Poff is less than a predetermined value and at least one of these parameters is greater than a predetermined threshold value, the determination system determines that an inter-cylinder air intake amount variation abnormality is occurring. |
