There are 3 basic fuel control systems used on the General Motors A-Body cars. The feedback carburetor vehicles use a system called Computer Command Control (CCC) System. The other two systems are fuel injection systems. One system is called Throttle Body Injection (TBI) ; this system uses an injector built into the throttle body. Throttle body injected vehicles appear very much like carbureted vehicles, but you'll notice there is no choke. The third system is Multi-Port Fuel Injection (MFI), or a variation known as Sequential-Fuel Injection (SFI). This MFI/SFI system has an injector mounted in the intake manifold at each intake valve. There is one injector for each cylinder.