Emissions Compliance

If a vehicle fails an emission test, it is probable that catalytic converter was not hot enough immediately prior to the test, or the vehicle had idled excessively long prior to the test.

The following encompasses most of the emissions measurement modes of current state idle test procedures:

• Ensure engine is at normal operating temperature and all accessories are turned off.
• Check emissions at idle.
• Operate engine at 2200-2800 RPM.
• Check emissions within 30 seconds.
• Return engine speed to idle.
• Check emissions within 30 seconds.

If any emission component is changed, PCM memory should be cleared before repeating state emission test procedure. See TESTS W/CODES article.

• Check ignition system. See BASIC TESTING article.
• Check for vacuum leaks.
• Check fuel delivery system. See SYSTEM/COMPONENT TESTS article.
• Check EGR system. See SYSTEM/COMPONENT TESTS article.
• Check PCV system.
• Check EVAP system. See SYSTEM/COMPONENT TESTS article.
• Check idle air control systems. See appropriate SYSTEM/COMPONENT TESTS article.
• Check for leaking or restricted exhaust system.
• Check condition of catalytic converter.
• Check cooling system.
• Check engine compression and mechanical condition.