The electronic fuel injection system is a fuel metering system with the amount of fuel delivered by the throttle body injectors (TBI) determined by an electronic signal supplied by the Electronic Control Module (ECM). The ECM monitors various engine and vehicle conditions to calculate the fuel delivery time (pulse width) of the injectors. The fuel pulse may be modified by the ECM to account for special operating conditions, such as cranking, cold starting, altitude, acceleration, and deceleration.
The ECM controls the exhaust emissions by modifying fuel delivery to achieve, as near as possible, and air/fuel ratio of 14.7:1. The injector "ON" time is determined by various inputs to the ECM. By increasing the injector pulse, more fuel is delivered, enriching the air/fuel ratio. Decreasing the injector pulse, leans the air/fuel ratio.