A throttle body assembly is an integral part of a fuel-injected engine’s air intake system. Its function is to regulate the amount of air that flows into the engine—accounting for factors such as throttle (gas pedal) position, idle speed, cold start warmup, and more. To perform these critical tasks, the throttle body is bolted in place between your engine’s intake manifold and air filter housing. A hinged metal plate inside the throttle body (known as a butterfly valve) opens to let more air in as the gas pedal is depressed. Because fuel injection systems are inherently computer controlled, information from various sensors mounted on the throttle body allows the vehicle’s engine management system to determine the optimum fuel flow rate based on multiple conditions.