As the automobiles move closer to the ULEV, ULEV-2 and SULEV requirements, OBD (on board diagnostic) will become a design challenge. The present OBD II designs involve the use of dual oxygen sensors to monitor the hydrocarbon performance of the catalytic converter. The aim of this study was twofold: Catalyst samples were aged on a spark ignited engine using a “fuel cut” engine aging cycle operated for 50 hours. Maximum catalyst temperatures during this aging cycle were 850-870°C. The effect of sulfur was determined by measuring aged catalyst performance using both indolene (∼100 ppm sulfur) and premium unleaded gasoline (∼350 ppm sulfur). The test for OBD performance was an oxygen storage capacity determination. The delay time between a front and a rear oxygen sensor was measured, as the engine was transitioned from a rich operating mode to a lean operating mode.This study showed that higher levels of fuel sulfur were associated with longer OBD delay times for both fresh and engine-aged catalysts, and that introduction of high fuel sulfur gasoline can cause errors in an OBD calibration algorithm developed for use with a low sulfur content gasoline.
Understanding Sulfur Interaction Key to OBD of Low Emission Vehicles
Sae Technical Papers
International Fuels & Lubricants Meeting & Exposition ; 2000
2000-10-16
Conference paper
English
Understanding sulfur interaction key to OBD of low emission vehicles
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