Recently, an Adaptive Transient Fuel Control (ATFC) algorithm was developed, using only a switching EGO sensor. This algorithm was tested extensively on a dynamometer and in a vehicle during real-life driving conditions. These tests have led to a number of modifications to increase its robustness and eliminate undesired interactions with other subsystems. Subsequently, it has been tested on a chassis dynamometer for emissions over the federal drive cycle using both certification and hesitation fuel. While the algorithm has been described in detail in a previous publication, the focus of this paper is on the experimental validation. Results from the various test stages are presented here. They show that the ATFC algorithm is an effective solution to increase A/F control robustness when dealing with a wide range of different fuels, especially during cold starts. Furthermore, the algorithm is expected to be able to deal successfully with changing A/F characteristics due to component aging (build up of intake valve deposits). The deterioration factor for 100K emissions levels due to transient fuel effects would be expected to be close to one throughout the life of the engine.