In a petrol (gasoline) internal combustion engine, the throttle is a valve that directly regulates the amount of air entering the engine, indirectly controlling the fuel burned on each cycle due to the fuel-injector or carburetor maintaining a relatively constant fuel/air ratio. In a motor vehicle the control used by the driver to regulate power is sometimes called the throttle pedal or accelerator. The throttle is typically a butterfly valve. In a fuel-injected engine, the throttle valve is housed in the throttle body. In a carbureted engine, it is found in the carburetor.