| 摘要 |
PROBLEM TO BE SOLVED: To continue air-fuel ratio control without causing problems such as deterioration of drivability or emission, or a torque shock when a target air-fuel ratio is extensively changed or right after transition from open loop control to feedback control. SOLUTION: A CPU 31 in an ECU 30 sets the target air-fuel ratio, it carries out correction responding to a degree of lean or rich of the set target air-fuel ratio, and it controls by feeding back an actual air-fuel ratio of exhaust gas exhausted from the engine 1 to the target air-fuel ratio. When it is determined that the target air-fuel ratio is largely changed such as in transition from stoichiometric air-fuel ratio feed back control to lean feedback control, the CPU 31 temporarily interrupts the feedback control, and it resumes the feedback control when a deviation between the actual air-fuel ratio and the target air-fuel ratio becomes a predetermined value or lower. COPYRIGHT: (C)2004,JPO
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