Fuel Injection System - Digital: Description

The General Motors Digital Fuel Injection (DFI) system is a speed density fuel system that accurately controls the air/fuel mixture into the engine to achieve desired performance and emissions goals.

The system consists of 11 major systems and 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.

The ECM is a digital electronic computer which monitors and controls all DFI system functions. The ECM controls amount of fuel metered through injector valves based upon engine demand and efficiency information. Fuel is supplied to engine through 2 electronically pulsed (timed) injector valves located in throttle body on top of the intake manifold.

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 article in COMPUTER CONTROLS section for more information.