Generally, if the throttle pedal is pressed further down, this will open the throttle body and allow more air to be pulled into the engine. The ECU will inject more fuel according to how much air is passing into the engine.
In order to fit the most users in every driving situation, ECU programme tend to higher fuel injection which is written by car manufacturer.
With SingTech ECO fuel saver, when the driver step on the accelerator, ECO fuel saver will receive the data from throttle pedal sensor or accelerate pedal sensor. ECO fuel saver will give reduced signal to ECU, then ECU will become aware of desired output fuel through sensors to keep engine going on.