Patent ID: 8499624
Filing Date: 2013-08-06
Classification: F02D

Abstract:
1. A method to determine a performance characteristic of an exhaust system of an engine, said system comprising an exhaust gas sensor configured to output an exhaust gas signal, said method comprising: fueling a combustion event in a cylinder at an air-fuel ratio selected to produce exhaust gas that is expected to be distinguishable by the exhaust gas sensor from exhaust gas produced by other combustion events, wherein the step of fueling a combustion event includes over-fueling by a rich factor a first combustion event in a first cylinder of the engine; and under-fueling by a lean factor a second combustion event in a second cylinder of the engine, wherein the rich factor and the lean factor are selected such that when exhaust gas from the first combustion event and the second combustion event are combined, the mixture is substantially stoichiometric; detecting exhaust gas in the exhaust system produced by the combustion event using the exhaust gas sensor; and determining the performance characteristic based on an exhaust gas signal indicative of the combustion event.