Engine control method for a vehicle with idle stop function

A method for controlling an engine of a vehicle with an idle stop function is provide to allow a transmission to be shifted from a neutral state to a driving state smoothly and quickly by appropriately controlling the engine output at a start point after the idle stop. A method for controlling an engine of a vehicle with an idle stop function comprises the steps of limiting the maximum output torque of the engine within a predetermined standard level when the engine satisfies a restart condition and starts after the idle stop, and releasing the limit of the maximum output torque of the engine by gradually increasing the limited maximum output torque according to the elapsed time. The step of limiting the maximum output torque of the engine continues until a signal indicating that a transmission controller has shifted from a neutral state to driving state is received.