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 GENERAL MOTORS DFI CONTROL SYSTEM in COMPUTERIZED ENGINE CONTROLS section for more information.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Fuel Injection System - Digital: Description

Use the Manual With the Right Hardware

When to See a Mechanic