Investigations of the spray formation of automotive port fuel injectors inside the port of a running SI engine and in a test chamber have been performed using two-dimensional Mie scattering, Laser Doppler Velocimetry (LDV) and Phase Doppler Anemometry (PDA). The liquid fuel distributions inside the spray cone (internal spray structure) in the engine port was detected by two-dimensional Mie measurements. For comparison and characterisation of gasoline fuel injectors the most important spray parameters like cone angles, tip penetration, droplet velocities and diameters were measured by this technique in a test chamber without the influence of air flow like in the engine. The examination of the injection inside the intake port showed large differences in the fuel distributions. The engine performance is very sensitive to the structures in these fuel distributions which depend on both, the air flow and the injection parameters. Different injector types cause different spray structures and show a different degree of robustness concerning changes in the air flow. Therefore it is necessary to perform both experiments. First for a general characterization the injector must be measured inside a test chamber providing comparable spray parameters without the effect of air flow and with less experimental effort. Second the spray behavior must be determined under running engine conditions preferable in a real engine. Both experimental ways are described including experimental setups, evaluation procedures and experimental results.