Section 276.203  Dilution - Steady-State Idle Exhaust Test and Transient Loaded Mode Exhaust Test

a)         Steady-State Idle Exhaust Test

            To prevent excess dilution in a steady-state idle exhaust emissions test described in Section 276.204, the sample probe shall be inserted a minimum of 10 inches into the vehicle's tailpipe.  Extension boots shall be utilized if it is impossible to insert the sample probe at least 10 inches into the tailpipe.  A vehicle emission test shall be invalid if the applicable emission standards contained in 35 Ill. Adm. Code 240 are met but the sum of the CO and CO₂ concentrations in the exhaust gas does not exceed 6 percent during the sample averaging period(s).

b)         Transient Loaded Mode Exhaust Test

            To prevent excess dilution in a transient loaded mode exhaust emissions test described in Section 276.207, the exhaust collection system shall be positioned to insure complete capture of the entire exhaust stream from the tailpipe during the transient driving cycle.  The test system shall verify that the entire exhaust stream is being collected through continuous monitoring of exhaust CO₂ generated during the transient driving cycle and comparison with theoretical levels of exhaust CO₂ produced by the vehicle being tested.  A vehicle emission test shall be invalid if the measured values fall below expected values during the transient driving cycle.  At a minimum, the emission test shall be invalid if five consecutive one-second average CO₂ values fall below 0.085 percent during seconds 5 through 220 of the transient driving cycle.

(Source:  Amended at 26 Ill. Reg. 8113, effective May 17, 2002)