To minimise pollution of the atmosphere from incompletely burned and evaporating gases, and to maintain good driveability and fuel economy, a number of emission control systems are used on these vehicles, according to market territory. They include the:
Positive Crankcase Ventilation (PCV) system. Evaporative Emission Control (EVAP) system.
Three-way catalytic converter (TWC) system.
The Sections in this Chapter include general
descriptions, checking procedures within the scope of the home mechanic and component renewal procedures (when possible) for each of the systems listed above.
Before assuming an emissions control system is malfunctioning, check the fuel and ignition systems carefully (see Chapters 4A and 5A). The diagnosis of some emission control devices requires specialised tools, equipment and training. If checking and servicing become too difficult or if a procedure is beyond the scope of your skills, consult your dealer service department or other repair workshop.
This doesn't mean, however, that emission control systems are particularly difficult to
maintain and repair. You can quickly and easily perform many checks and do most of the regular maintenance at home with common tune-up and hand tools. Note: The most frequent cause of emissions problems is simply a loose or broken electrical connector or vacuum hose, so always check the electrical connectors and vacuum hoses first.
Pay close attention to any special precautions outlined in this Chapter. It should be noted that the illustrations of the various systems may not exactly match the system installed on your vehicle because of changes made by the manufacturer during production or from year-to-year.
4B-2 Emission control systems