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Imbalance between cylinders is a major concern of a proper operation of reciprocating engines. An engine reliability and performance envelop, including life span, fuel consumption and emission, are strongly affected by an improper operation of the cylinders. To improve the engine quality, there is a strong need for a closed-loop control system to manage the amount of fuel injected to each individual cylinder. An advanced system to detect imbalance related faults in reciprocating engines which is based on the analysis of the engine's mechanical vibrations have been developed. The system is based on a firm theoretical background that provides a fundamental relation between the engine's vibration pattern and the relative characteristics of the combustion process in the different cylinders. With a single accelerometer mounted on the engine's block, online information related to the combustion process in each cylinder is provided by the system.

A correlation between engine dynamometer- and vehicle-aged catalysts has been established for novel lean-burn applications. A lean-burn, 1.8-L Ford Mondeo with a close-coupled three-way catalyst and an underfloor lean-NOx trap was used for this study. Vehicle aging of the emissions control system was done using a prescribed driving schedule. Engine dynamometer aging was done using a four-event aging cycle modified for lean-burn applications. The two aging methods were compared using maximum NOx conversion efficiencies measured during a two-mode dynamometer evaluation cycle. It was found that 75 h of four-event dynamometer aging is equivalent to 80,500 km of prescribed vehicle driving.