Fuel Injection System - Digital: Description
The General Motors digital fuel injection system (DFI) consists of 11 major sub-assemblies: fuel delivery, air induction, data sensors, Electronic Control Module (ECM), Electronic Spark Timing (EST), Idle Speed Control (ISC), emission controls, closed loop fuel control, system diagnostics, cruise control and torque converter clutch.
Fuel is supplied to engine through 2 electronically pulsed (timed) injector valves located in throttle body on top of intake manifold. The ECM controls amount of fuel metered through injector valves based upon engine demand and efficiency information. The ECM is a digital electronic computer which receives and computes signals from various sensors.
NOTE:
Primary sub-systems which affect fuel system operation will be covered in this section: fuel delivery, air induction, Idle Speed Control (ISC), data sensors, Electronic Control Module (ECM), and closed loop fuel control. Refer to "DFI CONTROL SYSTEM" in COMPUTERIZED ENGINE CONTROLS section for more information.