Q: a quick 2 car, 85kW engine, engine start normal, the idle speed is very high, the speed of the car after warm up to 1500r/min, idle speed can not be reduced, at the same time no reaction. Cleaning throttle is not valid. What is the trouble? Answer: according to the failure phenomenon: the engine idle speed 1500r/min, always can not fall down, at the same time acceleration no reaction, analysis has three kinds of possibilities: (1) the accelerator pedal position sensor bad; 2. The throttle position sensor bad; 3 computer bad. The electric throttle is equipped with an electronic throttle. The electronic throttle consists of an accelerated pedal module with an acceleration pedal position sensor, an engine control unit, a throttle control unit, and an electronic throttle control system fault indicator. The driver's foot directly controls the accelerator pedal, whose sensor sends the corresponding load signal to the engine control unit. The computer calculates the engine power required by the driver and converts this information into the engine torque value, then activates the throttle drive to open or close the throttle. While the throttle driver is activated, the computer also needs to consider other needs for increasing twisting, such as air conditioning access, automatic transmission gear, power steering, and so on. In addition, the computer also monitors the function of the electronic throttle control system. As for the throttle control unit, it is mainly responsible for providing the required air quality; the throttle driver activates the throttle according to the command of the engine control unit; the throttle angle sensor provides the feedback data of the throttle position to the engine; the electronic throttle fault indicator gives the driver an electronic throttle control. The system has failed. I once met a case of a car crash, which is similar to the phenomenon you described. The difference is that the fault light is lit. We first enter the engine system with a computer diagnostic instrument, and the fault code P1631, P1634, the former is said to speed the accelerator pedal position sensor 1 signal voltage is too high, the latter is the acceleration pedal position sensor 2 signal voltage too high. Check the accelerator pedal position sensor with multimeter. The 5V has good power supply and good tie up. It is concluded that the accelerator pedal position sensor is damaged. Fig. 1 shows an anatomical diagram of the accelerator pedal position sensor. In order to maximize security, some vehicles use signals from two acceleration pedal position sensors to identify the current position of the accelerator pedal, which is also known as a "redundant system". Redundant systems literally mean superfluous, and technically, if certain information is far higher than the requirements of system work, redundancy occurs. If there is a sensor signal distortion or interruption, the electronic throttle failure indicator light will light, if the other sensor is in the idle position, the engine goes to the idle condition; if it is load condition, the engine speed increases slowly. The system can also identify idle speed by brake light switch or brake pedal switch. However, the comfort system functions such as cruise or engine brake adjustment functions will be closed. If two sensor signals are distorted or interrupted, the electronic throttle fault lights are lit and the engine operates only at a high idle speed (maximum 1500r/min), and no longer responds to the action of the accelerator pedal. So, after you check, you need to replace the accelerator pedal position sensor or throttle position sensor, and idling acceleration should return to normal.