A Nissan sedan car caused too much idle speed after cleaning the throttle. After the car is connected, the engine is extinguished, the ignition switch is opened, the fault code is read with the decoder, and the "system is normal", and then the temperature of the engine coolant is cooled down to below 70 degrees, then the car enters the "work support" menu and chooses the "idle air learning". After the instrument shows the waiting screen, the idle speed still remains. No change, repeated trials, idle speed remains high. Later, the engine completely cooled the engine, to 30 degrees centigrade, again the car test, or can not complete the match, at this time, with the operation time extension, the engine cooling liquid temperature has exceeded 70 degrees C, only water pouring cooling liquid temperature sensor, and then the operation instrument "idle air learning", the result or It can't be done. Try to disconnect the battery line, like other cars, to clear the control unit of the learning value inside the control unit, then installed, using the decoder for idle air learning, or not successful. Finally, try to hang the clutch pedal, hold the engine to force the idle speed down, after repeated trial of two or three times, the idle speed dropped, to the outside interview of a circle of cars, back to the factory to extinguish, and try again, the idle speed is too high phenomenon, the speed in 1500r/min does not decline, the speed of the accelerator pedal after the speed is not down. Down to the normal speed, after the fire again start the car, idle air learning, this successfully completed. At that time, I saw the coolant temperature at 85 degrees Celsius. By the way, I saw the engine control unit part number of this car: 27310-ED51B.