A combustion control system for a direct injection engine includes a mean effective pressure (MEP) determination module, a coefficient of variation (COV) determination module, a spark timing module, and a fuel control module. The MEP determination module determines a MEP for a first combustion event of a cylinder based on cylinder pressure measured by a cylinder pressure sensor during the first combustion event. The COV determination module determines a COV for the cylinder based on the MEP. The spark timing module selectively sets a spark timing for a second combustion event of the cylinder based on the COV. The second combustion event is after the first combustion event. The fuel control module that selectively provides fuel for the second combustion event based on the COV.