Emission Control System

Component Locations:

In order to reduce exhaust emissions, these vehicles utilize an evaporative emission control system, air injection system, positive crankcase ventilation system and catalytic converters.

AIR INJECTION SYSTEM (AIR)

To reduce carbon monoxide and hydrocarbon emissions during engine warm-up, this system delivers air to the exhaust manifolds to aid oxidation. A diverter valve, twin check valves, electric solenoid valve and thermal vacuum valve control delivery of air pump output to air rails and exhaust manifolds.

EVAPORATIVE EMISSION CONTROL SYSTEM (EVAP)

When the engine is not running, the evaporative emission control system stores fuel tank vapors in a canister containing activated charcoal. A two-stage purging system controls delivery of stored vapors to the intake manifold during specified operating conditions.

POSITIVE CRANKCASE VENTILATION SYSTEM (PCV)

This system prevents crankcase fumes from being vented to atmosphere. It is designed to maintain a vacuum in the crankcase and pipe fumes into the intake manifold and then to the combustion chambers.

CATALYTIC CONVERTERS (CAT)

Catalytic converters reduce emissions of CO, NOx and HC. The 5.3L engine utilizes 4 ceramic monolith converters mounted in the exhaust system. One each are located near the exhaust manifold on each cylinder bank. Two additional converters are under the vehicle. Platinum and rhodium are commonly used as catalysts to stimulate reactions which reduce exhaust gases to carbon dioxide and water vapor.