GM Celebrity/Century/Ciera/6000 1982-1996 Repair Guide

Emission Control Systems


Emission control system constitute the largest body of emission control devices installed on A-Body cars. Many of these systems are controlled by or engine control computer. Included in this category are: Thermostatic Air Cleaner (THERMAC); Air Management System; Early Fuel Evaporation System (EFE); Exhaust Gas Recirculation (EGR); Computer Command Control System (CCC); Throttle Body Injection (TBI) ; Multi-Port Fuel Injection (MFI); Deceleration Valve; Mixture Control Solenoid (M/C); Throttle Position Sensor (TPS); Idle Speed Control (ISC); Electronic Spark Timing (EST); Torque Converter Clutch (TCC); Catalytic Converter and the Oxygen Sensor System. A brief description of each system and any applicable service procedures follows.

Many of the component testing is covered in chart format. The Computer Control Module ECM/PCM is capable of storing diagnostic codes. Many of the components test will be cover in the charts related to certain codes. Example is if the ECM/PCM see an improper signal from the coolant temperature sensor it will store a code 14. You would perform the test for Code 14 for the engine in your vehicle. If you wanted to test this component even thought the computer did not store a code you would still use the same chart and procedure.

There are 4 major electronic engine control systems covered in this section: Feedback Carburetor (also called Computer Command Control (CCC) System), Throttle Body Injection, Multi-Port Fuel Injection and Sequential Fuel Injection. You only need use the text and charts for the car's applicable system. Whereas Fuel System covers removal, installation and adjustment procedures, this section contains general descriptions of systems and components, as well as the testing charts needed to diagnose them.