understanding fuel injectors flow

[solid_snake2x]

http://www.overboost.com/story.asp?id=1358 click on the link

 

[peepsalot]

It can open slightly to let small amounts of fuel in and the door can be swung open as wide as it is capable of to let as much fuel pass through as its size will allow.

This part of the article bothers me. I always thought a fuel injector was either on or off. The amount of fuel is determined by the duration of time it is on during each intake stroke. Am I wrong?

 

[ROB-80E]

That's what I thought. Later on it does mention it though.

The duty cycle is how long that door stays open at one time. The longer the door is open, the more fuel flows out.

 

[ChiMSP]

subscring to read later.