An experimental technique was used in evaluating the influence of mixture preparation in the intake port on the performance of a steady-operating, 1.9L Ford engine. The fuel preparation components investigated in this study were vapor, droplets, and liquid streams. Engine performance was evaluated in terms of in-cylinder pressure and exhaust gas emissions. Fuel vapor, small droplets (Sauter mean diameter less than 10 mm), and liquid streams were produced and varied in a carefully-controlled mixture preparation system, which delivered an air/fuel mixture to an engine test cylinder. The air/fuel mixture was saturated prior to delivery to the cylinder so as to stabilize the fuel preparation components for study. Also, incorporated in the preparation system were devices for physically measuring the amount of fuel in the form of droplets and liquid streams.For a load of 50 kPa and a speed 1500 rpm, the effects of mixture preparation were evaluated for IMEP, COVimep, 10 - 90% Burn Angle, HC, CO, CO2, NO, NOx, and exhaust O2 at a stoichiometric air/fuel ratio. Results of the study generally showed that engine performance was significantly diminished by increasing the amount of fuel in liquid stream form (i.e. more wall-wetting).