A Chery A5 dual fuel taxi. When the vehicle is shifting or waiting for the red and green signal, the engine idling speed is high. Inspection and analysis: test the fault, true. Connect the fault detector to detect and store the trouble free code. To read the data flow, the engine idle speed is 1100 r/min, the acceleration pedal position sensor 1 signal voltage is 0.95 V, the acceleration pedal position sensor 2 signal voltage is 0.43 V. Then the fault detector was used to detect the signal voltage of accelerator pedal position sensor at the idling speed of the new vehicle at 0.74 V and 0.37 V respectively. The acceleration pedal position sensor of the car is 2 independently identical potentiometer sensors, which provide a signal voltage to the ECU, and the instantaneous signal voltage value sensor 1 is 2 times that of the sensor 2. In order to prevent the signal distortion caused by the voltage fluctuation of the generator, the contrast circuit is used inside the ECU. The signal voltage output by the sensor is compared with the standard voltage, and the ratio is used to judge the action amplitude of the accelerator pedal. Through two sets of data analysis, it is determined that the voltage signal provided to ECU when the acceleration pedal position sensor of the fault car is idle is too high, causing ECU to judge the error and cause the engine idle speed to be too high. Elimination method: replace the accelerator pedal assembly, and study according to the following methods: disconnect the ignition switch, do not step on the accelerator pedal, connect the ignition switch, slow down the accelerator pedal to the end, and maintain a period of time; release the accelerator pedal and start the engine.