| 摘要 |
An air-fuel ratio control using an A/F sensor which outputs a current representing an air-fuel ratio in response to a voltage applied thereto. If the A/F sensor is still in a state prior to activation and the actual air-fuel ratio is different from an air-fuel ratio represented by a current of the sensor in the state prior to activation when the engine is started, that is, if the air-fuel ratio is put on the rich side by an increased amount of fuel injected at a start of an internal combustion engine at a low temperature or other causes, for example a CPU employed in an ECU, determines whether the difference between the lambda -conversion value of the current of the A/F sensor and a target air-fuel ratio is equal to or greater than a predetermined value. If the determination is YES, a feedback control of the air-fuel ratio is started. Then, the CPU carries out the feedback control of the air-fuel ratio based on a deviation of the current of the A/F sensor from a current value representing the target air-fuel ratio.
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