PURPOSE: To improve drivability and start-up performance of an engine and the like at a cooling time in a wide range of low-high places by properly adjusting an air-fuel ratio in response to variation of atmospheric pressure at the cooling time of the engine.
CONSTITUTION: When it is judged by an warming condition judgement means 17 that a cooling water temperature of an engine is low than a set temperature and is under a cooling condition based on a signal from an water temperature sensor 23, judged a valve holding means 18 varies a fixed holding position of a flow control valves 8 based on a signal from a pressure sensor 24 in response to the conditions of atmospheric pressure. When atmospheric pressure is lowered, the position of the flow control valve 8 is varied to the opening side. Since the intake air supplied from an air bleed passage 7 is increased, change of air-fuel ratio of mixed air to overich is prevented.
YOSHINO YASUSHI
TANAKA HIROFUMI
