| 摘要 |
PROBLEM TO BE SOLVED: To advance the time of starting an air fuel ratio feedback control at the time of starting an engine under the condition that an air fuel ratio sensor is cold. SOLUTION: An A/F sensor 26 which outputs a current corresponding to an air fuel ratio according to the application of a voltage is arranged in the exhaust pipe 12 of an engine 1. At the time of starting the engine, a CPU51 in an ECU41 judges whether or not a difference between the λ transformed value of an element current (sensor output) and a target air fuel ratio is over a specified limit if the A/F sensor 26 is not yet activated and the actual air fuel ratio is different from the value equivalent to the output provided before the sensor is activated, i.e., for example, the air fuel ratio is rich by increased fuel amount at the time of starting the engine at low temperatures and, if the judgment is affirmed, the F/B-starting of air fuel ratio is permitted. At this time, the CPU51 F/B-controls the air fuel ratio relative to a target air fuel ratio based on a deviation between a current output from the A/F sensor 26 and a current value equivalent to a target air fuel ratio. |
