how does the TBI system work? -scientifically speaking

[dj_joker_2002]

OK what I want to know is this: if the TBI has a fuel pressure regulator, the IAC valve and the TPS and all this is controlled by the vehicles computer
then why does it matter the size of the injectors? Is it because of the bigger pipe less pressure/smaller pipe more pressure? why can't the computer auto adjust to different size injectors? anyone technicle enough to explain?

[Smiliesafari]

The simple explaination is: all of the components are designed to work together. When you make a change you've put something in the system that the other parts don't understand. The ECU only controls the system according to the inputs of all of the sensors. So, when you start to change things you also have to change the data base of the ECU.

[SafariRob]

Remember, too, that there is two modes of operation with TBI: open loop and closed loop. In the case of my 89, I discovered that using 350 injectors worked okay when the engine was in closed loop (IE, using the oxygen sensor to set the air/fuel ratio), but there were problems when running open loop (relying on an ECM stored set of injector on/off times).