What's the difference between an air flow sensor and a throttle opening sensor?

Air flow sensor, also known as air flow meter, is one of the important sensors of EFI engine. It converts the intake air flow into an electrical signal and sends it to the electronic control unit (ECU). As one of the basic signals to determine fuel injection, it is a sensor to measure the intake flow of the engine. In order to obtain the best mixture concentration under various working conditions, the electronically controlled gasoline injection engine must correctly measure the intake air entering the engine at each moment, which is the main basis for ECU to calculate (control) the fuel injection quantity. If the air flow sensor or circuit fails, the ECU can't get the correct intake signal, so it can't control the fuel injection normally, which will cause the mixture to be too rich or too lean and make the engine run abnormally. There are many types of air flow sensors in electronically controlled gasoline injection system. Common air flow sensors can be divided into vane (wing plate) type, core measuring type, hot wire type, hot film type, Karman vortex street type and so on according to their structural types.

Throttle position sensor, also known as throttle opening sensor or throttle switch, is a device for detecting engine state. The throttle position sensor is also called throttle opening sensor or throttle switch. Its main function is to detect whether the engine is in idle or load condition, acceleration or deceleration condition. It is essentially a variable resistor and several switches installed on the throttle body. The rotating shaft of the resistor is connected with the throttle valve, and it has two contacts: a fully open contact and an idle contact. When the throttle valve is in the idle position, the idle contact is closed and the idle working condition signal is output to the computer; When the throttle valve is in other positions, the idle contact is opened, and voltage signals with different angles relative to the throttle valve are output, and the computer identifies the engine load according to the signal voltage value; According to the change rate of signal voltage in a certain period of time, whether it is an acceleration state or a deceleration state is identified. According to these working conditions, the computer corrects the fuel injection quantity or controls the fuel cut-off.