Does the throttle always idle when the car starts? If the throttle is off when starting, it won't start. What is the reason?

When the car starts, the throttle is usually off. The main function of the throttle valve is to control the air intake of the engine and adjust the engine speed. When starting, the throttle valve is closed to ensure the normal start of the engine.

If the throttle valve cannot be completely closed when starting, it may be due to one of the following reasons:

1. Throttle blockage: The throttle will be blocked by dust, oil stains and other substances, resulting in failure to close. This may affect the intake air volume and speed of the engine, thus making it difficult to start. Regular cleaning of the throttle and parts around the throttle can prevent this problem.

2. Throttle position sensor failure: The vehicle is equipped with a throttle position sensor to monitor the position of the throttle. If the sensor is damaged or fails, the throttle may not be completely closed or closed, thus affecting the engine start. At this time, it is necessary to check and replace the sensor.

3. Throttle control unit problem: The throttle control unit is responsible for controlling the opening and closing of the throttle. If the control unit fails, the throttle may not be closed completely, thus affecting the engine starting. Repairing or replacing the throttle control unit may require professional maintenance services.

When the throttle cannot be closed, it is recommended to contact a professional automobile maintenance technician or the service center of the vehicle manufacturer for inspection and maintenance as soon as possible.