SPLIT LAMBDA FUELING OPERATION SYSTEMS AND METHODS

Methods and systems for operating an engine with split lambda modes are provided. At least one example method comprises, while operating an engine in a condition that is within a resonant frequency region for a default split lambda mode, carrying out a rolling split lambda mode. The engine may be operated with only stoichiometric engine cycles in the default split lambda mode, the stoichiometric engine cycles including enleaned and enriched cylinders. Further, the engine may be operated with a plurality of non-stoichiometric engine cycles when carrying out the rolling split lambda mode, the plurality of non-stoichiometric engine cycles including at least one rich engine cycle and at least one lean engine cycle.