The electronic throttle body fuel injection system is a fuel metering system with the amount of fuel delivered by the throttle body injector(s) determined by an electronic signal supplied by the Computer Control Module (ECM/PCM). The ECM/PCM monitors various engine and vehicle conditions to calculate the fuel delivery time (pulse width) of the injector(s). The fuel pulse may be modified by the ECM/PCM to account for special operating conditions, such as cranking, cold starting, altitude, acceleration, and deceleration.
The Throttle Body Injection (TBI) system provides a means of fuel distribution for controlling exhaust emissions within legislated limits. The TBI system, by precisely controlling the air/fuel mixture under all operating conditions, provides as near as possible complete combustion.
This is accomplished by using an Computer Control Module (ECM/PCM) (a small on-board microcomputer) that receives electrical inputs from various sensors about engine operating conditions. An oxygen sensor in the main exhaust stream functions to provide feedback information to the ECM/PCM as to the oxygen content, lean or rich, in the exhaust. The ECM/PCM uses this information from the oxygen sensor, and other sensors, to modify fuel delivery to achieve, as near as possible, an ideal air/fuel ratio of 14.7:1. This air/fuel ratio allows the 3-way catalytic converter to be more efficient in the conversion process of reducing exhaust emissions while at the same time providing acceptable levels of driveability and fuel economy.