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In the current study a single cylinder Spark Ignited engine has been operated in Controlled Auto Ignition mode with centrally mounted spray guided direct injection, employing negative valve overlap to achieve the conditions required for auto-ignition. The injector is a type known in the market and utilises air at elevated pressure to assist preparation of the fuel and delivery of the fuel spray into the combustion chamber. Operation of the injector enables a high degree of control for fuel and air delivery, particularly with regard to stratification of fuel, temperature, air and turbulence within the chamber. Engine test data show that variation in injection parameters at a fixed engine condition yields high authority over the CAI combustion process. A range of combustion phasing is achieved from 355 to 375 degrees ATDC for the timing of 50% Mass Fraction Burned, whilst the range of maximum pressure rise rate is 70 to 450 kPa / degree.