The present invention relates to methods for robust controlled
auto-ignition and spark ignited combustion controls in gasoline
direct-injection engines, including transients, using either exhaust
re-breathing or a combination of exhaust re-compression and re-breathing
valve strategy. These methods are capable of enabling engine operation
with either lean of stoichiometric or stoichiometric air/fuel ratio for
oxides of nitrogen (NOx) control, with varying exhaust gas recirculation
(EGR) rates and throttle valve positions for knock control, and with a
combination of homogeneous charge compression ignition (HCCI) and spark
ignition (SI) combustion modes to optimize fuel economy over a wide range
of engine operating conditions.