High-rotating idle speed control device of engine for vehicle

The invention provides a high-rotating idle speed control device of an engine for a vehicle, the engine is preheated by opening auxiliary air valve fixed in an auxiliary inhale passage bypassing a throttle valve, the ignition time is delayed for preventing knock, thereby, the engine speed fits close a target idle speed, preheating end can be rapidly and accurately detected even if in an environment that the engine temperature is difficult to raise for avoiding long time uselessness of high-rotating idle speed control. delay angle detection mechanism is used for judging whether the total delayangle amount to the basic ignition time in delay angle control based on a ignition time controlling mechanism (36) reaches a specified value, and when the specified value is reached, an end signal forending high rotating idle speed control is output. An auxiliary air valve controlling mechanism (35) makes an auxiliary air valve (25) becoming a full cut-off state based on the end signal output from the delay angle detection mechanism (37).