How does the throttle position sensor work?

The throttle position sensor is installed on the throttle valve body, and the throttle opening can be converted into a voltage signal by stepping on the throttle valve and sent to the computer board. The throttle position sensor is essentially a ceramic film resistance potentiometer, and its group value changes with the throttle opening. The 5V voltage output by the computer board is applied to one end of the throttle potentiometer, and the other end is grounded. The sliding contact arm outputs a voltage of about 0-4.8V according to different positions. According to this voltage, the computer board can increase or decrease the injection without adjusting the pulse width of the fuel injector. When the speed is higher than 3000 rpm, the idle contact on the accelerator is closed and the computer board gives instructions. Many models have no idle contact on the accelerator, and this function has been replaced by the speed sensor signal on the car.

Some models not only convert the throttle position sensor into voltage signal, but also convert the voltage signal into percentage square wave signal with adjustable pulse width in the computer board through V/F conversion circuit, which is mostly used for automatic transmission control of Audi/Volkswagen cars.

The throttle position signal is mainly used to detect the air-fuel ratio in the intake air, so as to control the fuel injection quantity of the nozzle. However, in computer board control, the throttle position signal is often used as the required air intake mode, while the air flow meter or pressure sensor signal is used as the actual air intake. Therefore, when testing the computer board, adjusting the throttle position signal will find that the fuel injection pulse width changes back to the original fuel injection pulse width again and again, which is not as sensitive as the air flowmeter and pressure sensor, but when these two signals fail,