Technical Paper
Determination of Catalyst Oxidation and Reduction Efficiencies from Tailpipe Emissions Measurements
1997-10-01
972911
The Emissions Research Laboratory (ERL) of the Arizona Department of Environmental Quality (ADEQ) has developed tests to determine, in situ, both the oxidation and reduction capabilities of light duty, spark ignition vehicle catalysts. The tests require minimal system intrusion; determination of oxidation efficiency is essentially nonintrusive, but reduction efficiency measurement requires replacement of the oxygen sensor with a high precision universal exhaust gas oxygen (UEGO) sensor. The vehicle is operated on a dynamometer at 40mph steady state using the IM240 specified loading for that vehicle. To ensure proper fueling, the engine-out A/F ratio is measured. This measurement can be taken at the tailpipe with secondary air injection disabled, if present. Oxidation efficiencies for hydrocarbon (HC) and carbon monoxide (CO) require normal vehicle configuration (secondary air active, if present) and tailpipe measurements of total HC and methane (CH4).
