4-CYL EFI System: Description

NOTE: For more information covered on this system refer to article FUEL INJECTION SYSTEM SPECIFICATIONS in the FUEL SYSTEMS section. Additional diagnostic information that relates strictly to the fuel portion of this system can be found in the article FUEL INJECTION SYSTEM - TBI or in the article called FUEL INJECTION SYSTEM - MULTI-POINT in the FUEL SYSTEMS section.

The computerized engine control systems used on 2.2L and 2.5L fuel injected engines control the fuel system, ignition system and emission control system for proper engine operation. Throttle Body Injection (TBI) is used on non-turbo models, while Multi-Point Fuel Injection is used on turbo models.

In order to control these systems, the computer monitors several engine and vehicle operating conditions. The engine conditions monitored include: manifold absolute pressure, throttle position, throttle body temperature (non-turbo only), coolant temperature, charge temperature (turbo only), manifold air temperature, exhaust gas oxygen content and vehicle distance/engine speed.

Vehicle conditions monitored include vehicle speed and the status (off or on) of several vehicle systems that affect engine load. These include the transmission neutral/safety, brake light and A/C clutch switches.

The engine control computer consists of 2 separate modules. The logic module processes all sensor inputs and controls all low power output devices. The logic module also controls the power module. The power module controls injector(s), ignition coil and the auto shutdown relay.

Fig 1: Computer, Input Sensors & Output Devices (Non-Turbo)

Courtesy of CHRYSLER MOTORS.

Fig 2: Computer, Input Sensors & Output Devices (Turbo)

Courtesy of CHRYSLER MOTORS.