The main systems installed on vehicles and described in this manual include:
- Contactless ignition system
- Air intake system
- Coasting lean system
- Deceleration control system
- Intake air temperature control system
- Positive crankcase ventilation (PCV)
The driving economy indicator system, although not strictly speaking related to emissions, shares a control unit with the coasting system and is therefore included in this Section.
The chapters in this Section include a general description, verification procedures (where possible) and replacement procedures (where equipped), for each of the systems listed above.
Before assuming that the emission control system is malfunctioning, carefully check the fuel and ignition systems. In some cases, special tools and equipment are required, as well as specialized training, to accurately diagnose the causes of rough handling or hard starting. If inspection and maintenance become too difficult, or if these procedures are beyond the ability of a home mechanic, consult your dealer's maintenance department. This, however, does not necessarily mean that emission control systems are particularly difficult to maintain and refurbish. You will be able to quickly and easily make the most (if not all) from checks and regular maintenance at home, general tuning methods and hand tools.
Note: The most common cause of emissions system failures is a loose or broken vacuum hose or electrical wiring connection. Therefore, always check the hose and wiring connections first.
Pay particular attention to any special precautions outlined in this Chapter. It should be noted that illustrations of various systems may not accurately identify the system installed on your vehicle due to changes made by the manufacturer during production or from year to year.