Computers and Control Systems: Description and Operation

The Throttle Body Fuel Injection System provides a means of fuel distribution for controlling exhaust emissions within the required limits, by precisely controlling the air/fuel ratio under all operating conditions. This is accomplished by means of an Electronic Control Module (ECM) which receives electrical signals from various sensors indicating engine operating conditions, and varies the fuel delivery time (pulse width) of the injector accordingly. The ECM may modify the fuel pulse to compensate for special operating conditions such as cranking, cold starting, altitude, acceleration and deceleration. By increasing the fuel pulse, more fuel is delivered and the air/fuel mixture is enriched. When the fuel pulse is decreased, the air/fuel ratio is decreased. The throttle body is located on the intake manifold where fuel and air are distributed through a single bore in the throttle body. Air for combustion is controlled by a single throttle valve. Fuel for combustion is supplied by a single fuel injector mounted on the TBI Assembly.