How does a throttle body work?

Answer 1

It works with an electric fuel pump and pressure. ^^that guy is an A-Hole^^

here's a good answer... TBI Throttle Body Injection is a very versatile, highly adaptable form of electronic controlled mechanical fuel injection. TBI provides the optimum mixture ratio of air and fuel at all stages of combustion. TBI has immediate response characteristics to constantly changing conditions and allows the engine to run with the leanest possible air / fuel mixture ratio, greatly reducing exhaust gas emissions. Because it's air / fuel mixture is so precise, based upon much more than simple engine vacuum and other mechanical metering means, TBI naturally enjoys an increase in fuel economy over a simple mechanical form of fuel introduction such as a outdated carburetor. The TBI form of EFI is controlled by the ECM (Electronic Command Module) which controls the TBI based EFI system through all stages of operation according to data received regarding the current state of engine performance, speed, and load. The main component of this system is the TBI throttle body injector, which is mounted on top of the intake manifold, much like a carburetor. The throttle body injector is composed of two different parts; the throttle body itself, and the injector assembly. Hard to understand, isn't it? The throttle body is in fact, a large throttle valve, with a pair of linked butterfly hinged flapper valves, which are controlled by a simple mechanical linkage to the accelerator pedal. Depressing the accelerator pedal will force the throttle valve to butterfly open further and further, increasing the flow of air through the throttle valve and instructing the ECM to add more fuel, thus producing more power, faster speed, and acceleration.Attached to the body of the TBI unit are two sensors; the TPS throttle position sensor, and the IAC idle air control assembly. The ECM uses the TPS to determine the accurate position of the throttle body valve, it's degree of cycling, and how open it is (0% to 100%). The ECM takes readings from the IAC in order to maintain a constant idle speed during normal engine operation, during all stages of power, load, and combustion. The fuel metering assembly contains a fuel pressure regulator which dampens the pulsations and turbulence generated from the very high pressure fuel pump. Think of the FPR as a conditioner that smoothes out the flow of fuel from the outside to the inside of the fuel metering assembly. The FPR also maintains a constant, steady pressure at the injector assembly. Dual fuel injectors are mounted over the throttle valve, synchronized, and raised slightly over a venturi (narrowing radius) throat. Each injector is controlled by the ECM through an electrically initiated solenoid (switch). The precise amount of fuel delivered by each injector is varied by the amount of time that the solenoid holds the injector plunger open for operation. A high pressure, high volume electric fuel pump is used with the TBI system. This pump is located within the fuel tank itself (which can be a PITA if you have to replace it). Once the ignition key is inserted into the ignition, and the ignition moved to the RUN or START position, the fuel pump relay instantly initiates the pump, beginning the transfer of fuel (via the pump) from the tank to the injectors. A safety relay in the system shuts the pump off after two seconds, to keep the fuel from flooding. Failure of the fuel pump relay will allow the fuel pump to operate only after four pounds of oil pressure have built up. A high capacity fuel filter, similar to an in-line variety, is located on the left side of the vehicle, at the rear of the engine. Two common mistakes when working with the EFI system. The fuel system is pressurized. If you remove a fuel line, you could/will get a face full of fuel! The fuel pump used on the EFI system is much more powerful than that found on a carburetor installation. For this very reason, the second problem is that you cannot use a EFI fuel pump to feed a carburetor, and you cannot use a normal carburetor mechanical style fuel pump (low pressure) to feed a EFI system. In order to work on any part of the EFI system, you must first depressurize your fuel system!!!!! The ECM found in General Motors' cars has the capability to 'learn' or modify it's programming with regard to differing fuel requirements over time. Don't get excited. This is not HAL from 2001: A Space Odyssey, and it's certainly not some super advanced neural net processor like the T800 Endoskeleton had in Terminator and T2. It's quite a bit simpler, but its a complex computer nonetheless, and it can adjust to different conditions easily. It learns, just like a human child, and that's the best way to put it. It doesn't forget when you turn your car off either. But, if you ever change your battery, or your battery goes dead for any reason, your computer will lose it's stored 'memory' and will have to relearn everything. It's a quick learner, but it's something you don't really want to go through all the time. The computer's instructions are contained on a PROM (Programmable Read Only Memory), which means that the computer can change it's operation according to pending needs. It then stores this new information, and how it should act, on the PROM chip. Since the PROM isn't volatile, it doesn't lose it's information when the battery power is cut off or the keys are taken out of the ignition. But the computer takes a little while to adapt. So if you add a new cold air or ram air induction system and the car doesn't respond instantly, don't get depressed. The computer has just been handed a new parameter, it's working under new data and conditions, and it could take it a little while to figure out that the new cold / ram air isn't just a fluke, and that it should adjust to the new 'constant', but adjust it will. Be patient. The computer can make up for quite a bit of ham fistedness, but only to a limit. And after that limit is exceeded? Well, you could always learn to program your own chips, and we may get to that later... But I don't think it will come down to getting that serious. Credit to: http://www.goingfaster.com/spo/tbi.html