PURPOSE: To obtain a stable idling condition when the speed change position of an automatic transmission is in either of traveling or no-traveling by varying a feedback control characteristic in accordance with the magnitude of an external load.
CONSTITUTION: A control unit 28 reads the signal of a water temperature sensor 18 and calculates a basic air quantity and a target idling speed in accordance with an engine water temperature. And, the deviation between the target idling speed and an engine speed is calculated to set a feedback control gain in accordance with the deviation. Here, it is judged whether the condition of an automatic transmission 27 is in an N range or a D range from the on/off of an inhibitor switch 31. And, at the time of the N range, since the period of variation in engine speed is shorter as compared with that in the D range, a larger feedback control gain is set for the same deviation in engine speed. Thereby, good responsiveness can be obtained at the time of the N range while preventing controlling hunting at the time of the D range, to carry out an engine speed control with high degree of stability.
HIRANO HIROSHI
SASAKI KAZUTOMO
