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tony1 · 01-24-2010, 06:03 PM

not true ... here's from the Illinois site:
About the Test: Understanding the Illinois Vehicle Emissions Test

What Vehicle Emissions Tests are Performed in Illinois?

Two different types of tests are used in Illinois.

An OBD test (On Board Diagnostics) is used for most 1996 and newer model year passenger cars and light duty trucks, including vans and sport utility vehicles.
A single-speed idle exhaust test and gas cap pressure test is used for gasoline-powered heavy duty trucks and certain passenger cars and light duty vehicles that were certified by the federal government to be manufactured without OBD systems.

How is the OBD test performed?

The OBD test consists of connecting a scan tool to a vehicle's on-board computer to determine the OBD system status (readiness checks), to determine whether the Malfunction Indicator Light (MIL) is commanded to be illuminated, and to retrieve any stored diagnostic trouble codes.
Vehicles will pass the OBD test if the OBD system is working, all required emissions system readiness checks have been completed, and the MIL is not commanded to be illuminated.
Vehicles will fail the OBD test if the MIL is commanded to be illuminated and diagnostic codes are present. Vehicles will also fail if the OBD system is inoperable or if the OBD connector is missing, damaged, or inaccessible.
Check the “Understanding On-Board Diagnostics (OBD)” frequently asked questions page for further information.
How are the Idle Exhaust and Gas Cap Tests Performed?

Idle Exhaust Test

The idle exhaust test uses a tailpipe probe and emissions analyzer to measure the level of ozone-forming exhaust pollutants (carbon monoxide (CO) and hydrocarbon (HC)) in the vehicle's exhaust at idle speed.
If the levels of both of these pollutants are below applicable standards, the vehicle will pass the idle exhaust test. If the levels of one or both pollutants is above the applicable standard, the vehicle will receive a second-chance test following a period of high-idle preconditioning. If the level of either pollutant is still above the applicable idle test standards when re-tested, the vehicle will fail the idle test.
Gas Cap Test

The gas cap test is a functional check of the gas cap's seal. This test determines whether excessive levels of evaporative emissions (gasoline fumes) can escape from a vehicle's gas tank into the atmosphere. The gas cap is removed from the vehicle's fuel tank filler neck and attached to the testing unit which then applies pressure to the gas cap to check for leaks. If the gas cap cannot maintain the prescribed pressure, the vehicle will fail the gas cap test.
Check the “Understanding Idle Tests and Gas Cap Tests” frequently asked questions page for further information.

01-24-2010, 06:03 PM	#6
tony1 Drives: 2SS/RS Vortech/L99 Join Date: Jan 2010 Location: CHICAGO Posts: 474	not true ... here's from the Illinois site: About the Test: Understanding the Illinois Vehicle Emissions Test What Vehicle Emissions Tests are Performed in Illinois? Two different types of tests are used in Illinois. An OBD test (On Board Diagnostics) is used for most 1996 and newer model year passenger cars and light duty trucks, including vans and sport utility vehicles. A single-speed idle exhaust test and gas cap pressure test is used for gasoline-powered heavy duty trucks and certain passenger cars and light duty vehicles that were certified by the federal government to be manufactured without OBD systems. How is the OBD test performed? The OBD test consists of connecting a scan tool to a vehicle's on-board computer to determine the OBD system status (readiness checks), to determine whether the Malfunction Indicator Light (MIL) is commanded to be illuminated, and to retrieve any stored diagnostic trouble codes. Vehicles will pass the OBD test if the OBD system is working, all required emissions system readiness checks have been completed, and the MIL is not commanded to be illuminated. Vehicles will fail the OBD test if the MIL is commanded to be illuminated and diagnostic codes are present. Vehicles will also fail if the OBD system is inoperable or if the OBD connector is missing, damaged, or inaccessible. Check the “Understanding On-Board Diagnostics (OBD)” frequently asked questions page for further information. How are the Idle Exhaust and Gas Cap Tests Performed? Idle Exhaust Test The idle exhaust test uses a tailpipe probe and emissions analyzer to measure the level of ozone-forming exhaust pollutants (carbon monoxide (CO) and hydrocarbon (HC)) in the vehicle's exhaust at idle speed. If the levels of both of these pollutants are below applicable standards, the vehicle will pass the idle exhaust test. If the levels of one or both pollutants is above the applicable standard, the vehicle will receive a second-chance test following a period of high-idle preconditioning. If the level of either pollutant is still above the applicable idle test standards when re-tested, the vehicle will fail the idle test. Gas Cap Test The gas cap test is a functional check of the gas cap's seal. This test determines whether excessive levels of evaporative emissions (gasoline fumes) can escape from a vehicle's gas tank into the atmosphere. The gas cap is removed from the vehicle's fuel tank filler neck and attached to the testing unit which then applies pressure to the gas cap to check for leaks. If the gas cap cannot maintain the prescribed pressure, the vehicle will fail the gas cap test. Check the “Understanding Idle Tests and Gas Cap Tests” frequently asked questions page for further information.