| 摘要 |
PURPOSE:To prevent instability of idle and improve the operation performance of an engine by suspending feedback control when idle is suspended and carrying-out control lean for open loop control and setting the air-fuel ratio on the lean side. CONSTITUTION:An engine 10 for car takes the measure to purifying exhaust gas by using an air-fuel ratio sensor 34 and three-dimensional catalyst 38. When an idle switch 18 is ON in an engine controller 52 and the output of a car-speed sensor 50 is zero, idle suspension is judged. In this case, feedback control is suspended, and lean control for open loop control is executed, through deceleration and reduction of amount, so that the air-fuel ratio is set on the lean side in comparison with an aimed air-fuel ratio. Thus, undesirable state such as idle instability in idle suspension is prevented, and the operation performance of the engine is improved. |
