General System Description

Fig. 2 Typical multi-point electronic fuel injection system components. 1985-87 models:

This system combines an electronic fuel and spark advance control system with a turbocharged intake system to provide a precise air/fuel ratio under all driving conditions. This system utilizes a logic module, a digital pre-programmed computer, to regulate ignition timing, air/fuel ratio, emission control devices and idle speed.
Various sensors provide the input necessary for the logic module to correctly regulate fuel flow at the fuel injectors, Fig. 2. These include manifold absolute pressure, throttle position, oxygen feedback, coolant temperature, charge temperature, and vehicle speed sensors. In addition to the sensors, various switches also provide important information. These include transmission neutral safety, heated backlight (1984), brake (1987) and A/C clutch switches.
Inputs to the logic module are converted into signals sent to the [1][2]power module. These signals cause the power module to change either the fuel flow at the injector, ignition timing or both.
The logic module tests many of its own input and output circuits. If a problem is detected in a major system, the information is stored in the logic module. This information can be displayed by a flashing light emitting diode (LED) located on the instrument panel, or by connecting a diagnostic readout and reading a numbered display which corresponds to a specific problem.