See Figure 1
The Throttle body Fuel Injection (TFI) system supplies the combustion chambers with an air/fuel mixture of optimized ratio under widely diverse driving conditions. The TFI system utilizes a single-point throttle body fuel injection system, which injects fuel into the throttle body through one injector.
The TFI system is composed of two major sub-systems: air/fuel delivery and electronic engine controls. The electronic engine control sub-system is covered in Driveability & Emission Controls of this repair guide.
The main components of the air/fuel delivery sub-system are the fuel tank, fuel pump, fuel filter, throttle body (including the fuel injector, the fuel pressure regulator, the air valve and the ISC valve), fuel lines, and the air cleaner. The fuel filter and air cleaner are both covered in General Information & Maintenance , and the air valve and ISC valve are covered later in this repair guide.