Emission Control Systems: Testing and Inspection
The emission control systems are installed to reduce the amount of HC, CO and NOx exhausted from the engine ((3), (4) and (5)), to prevent the atmospheric release of blow-by gas-containing HC (1) and evaporated fuel containing HC being released from the fuel tank (2).
The function of each system is shown in these table.
To ensure proper operation of all emission control system components it is necessary to perform a visual inspection. Refer to the Vehicle Emission Control Information Label and the Emission Control Application Charts in this manual for emission control component installation. During this inspection, vacuum hoses should be checked for condition and proper connections. Vacuum hoses should be free of pinches, cuts, cracks and disconnects. In areas where hoses are difficult to view, an inspection mirror may be required. On 1970 and later models, emission control vacuum hose routing should be confirmed by referring to the vacuum hose routing on the Vehicle Emission Control Information or Vacuum Hose Routing Label, which should be affixed in the vehicle's engine compartment. If a vacuum hose routing modification has been authorized by the vehicle manufacturer, an Emission Control Modification Label should be affixed to the engine compartment noting this change. Any other modifications to the vacuum hose routing should be considered suspect.
Engine compartment wiring harnesses should be checked for proper routing and loose or disconnected electrical connectors. Wiring should also be checked for burned or chaffed insulation. Also ensure wiring is not in contact with sharp edges, exhaust manifolds or in places where wiring may be pinched. Check ignition wiring for heat damage and deterioration. Also note condition of distributor cap.
Check for disconnected choke assemblies and other carburetor components. Also inspect for unauthorized modifications to the fuel system. On models with AIR pump, inspect for missing or improperly adjusted pump drive belt. On models with EGR, ensure all components are properly connected. While viewing underhood area with engine operating, inspect for engine misfire, unstable idle speed and abnormal noises. Also note any fuel, coolant engine oil, vacuum, exhaust or compression leaks, as these may effect engine or emission control system operation.
Check exhaust system for deterioration, damage and exhaust leaks. On models which require a catalytic converter, ensure catalytic converter is in place. Also inspect for unauthorized modifications. On models with catalytic converter, ensure fuel restrictor in fuel tank filler neck is in place.
When in passenger compartment of vehicle, check instrument panel for any illuminated Check Engine, Power Loss or Emission Reminder indicator lamps. Illumination of these lamps could be an indication of a malfunctioning or inoperative emission control or related system.