What do Fuel INjectors do??? when do you use them?? i want to know all the details on them?? thanks/.....

Fuel injectors inject fuel. You use them.....always. If your car is on, you're using your fuel injectors. They basically spray gasoline into your cylinders (the cylinders being the things surrounding the pistons which are the things that our scion engines have four of, that go up and down, and make the car move). The amount of fuel sprayed by the fuel injectors is determined by the amount of air moving into the cylinders. More air, more fuel.......this maintains a consistent combustion.......unless there's something wrong with your car.

KiL

Fuel injectors spray (measured in time and distance<miliseconds and pulse width>)according to the mass air flow sensor input, coolant temp, baro (measured in hertz) crank and cam sensors (for timing of the spray) and input of other sensors for accurate combustion of the little box. Go to the library and have fun. It's simple in it's complexity.

Some more information:

http://www.sdsefi.com/injectors.htm

-john

However, don't think installing larger injectors will equal more power. Unless you can feed it with enough air (I.E Forced Induction), you'll see no gains at all.

Correct, larger injectors do not = more hp. The computer will just shorten the pulse to inject the correct amount of fuel that the air needs for correct combustion.

In a modified engine that has increased air flow larger injectors MAY be needed so the injectors do not get over worked and fail.

ken