Air Flow Sensor and TPS.

The air flow sensor takes in incoming air and measures how much is going into the engine. The flap is connected to the ECU and the movement of the flap determines how much air is going in. If there is little flap movement then the ECU will know that not much air is coming in so it will send in little fuel to match. If the flap was fully open then the ECU would send in more fuel because it reads that there is alot of air coming through. The air then goes through to the butterfly. The TPS (throttle position sensor) is connected to the butterfly. It reads what position the throttle is in and adjusts the butterfly to open up (amount opened depends on throttle position) to let air in. If the throttle is pushed down a little, the butterfly will open up a little, letting a little amount of air through. The TPS is connected to the MAP (manifold absolute pressure sensor). This measures pressure inside intake manifold. When the throttle is wide open, vacuum from the MAP drops. The engine sucks in more air which requires more fuel to keep the air/fuel ratio balanced. If throttle is near closed, less power is needed from the engine causing vacuum to increase. MAP senses this and ECU responds by leaning out the fuel mix.