IDLE ROTATION SPEED CONTROL DEVICE FOR BIFUEL ENGINE

Disclosed is an idle rotation speed control device for a bi-fuel engine, wherein an electronic throttle device for adjusting the air intake quantity during an idle operation is provided in an intake passage of a bi-fuel engine. An electronic control unit (ECU) controls the electronic throttle device on the basis of a control value so that the idle rotation speed reaches a target idle rotation speed. When an idle operation using gasoline is switched to an idle operation using CNG, the ECU corrects the calculated control value on the basis of a correction value, to correct the air intake quantity in accordance with the use of CNG Furthermore, the ECU adjusts the air intake quantity by controlling the electronic throttle device on the basis of the corrected control value.