General System Description

Fig. 3 Multi-point electronic fuel injection system components. 1988 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 Single Module Engine Controller (SMEC), a digital pre-programmed computer, to regulate ignition timing, air/fuel ratio, emission control devices, cooling fan, charging system, turbocharger waste gate and idle speed.
Various sensors provide the input necessary for the SMEC to correctly regulate fuel flow at the fuel injectors, Fig. 3. These include manifold absolute pressure, throttle position, oxygen feedback, coolant temperature, charge temperature (Turbo II), vehicle distance and detonation sensors. In addition to the sensors, various switches also provide important information. These include transmission neutral safety, brake, speed control and A/C clutch switches. These signals cause the SMEC change either the fuel flow at the injector, ignition timing or both.
The SMEC tests many of its own input and output circuits. If a problem is detected in a major system, the information is stored in the memory. This information can be displayed by a instrument panel check engine lamp, or by connecting a diagnostic readout and reading a numbered display which corresponds to a specific problem.