This product does not modify the air/fuel ratio, so the engine will continue to match the measured incoming air with a appropriate amount of fuel. This vehicles feature wideband air/fuel sensors from the factory, which allows the ECU to measure and control air/fuel in realtime at all throttle positions. We saw no issues with regards to the air fuel ratio when testing this product on our dyno with a F150 3.5L Ecoboost and on a Fusion 2.0L.