Abstract
A system comprises an engine including a plurality of cylinders. A first intake throttle is positioned upstream of a first set of cylinders of the plurality of cylinders. The first intake throttle provides air at a first flow rate to the first set of cylinders so as to produce a lean air/fuel mixture in the first set of cylinders. A second intake throttle is positioned upstream of a second set of cylinders included in the plurality of cylinders and in parallel of the first intake throttle. The second intake throttle provides air at a second flow rate to the second set of cylinders so as to produce a rich air/fuel mixture in the second set of cylinders.