Fuel Injector Cleaner is a chemical additive poured directly into the fuel tank. It mixes with the gasoline or diesel and cycles through the system to clean the internal components of the fuel injectors. Modern injectors have microscopic spray holes that can easily become clogged with carbon deposits or varnish from low-quality fuel, distorting the spray pattern. Using this cleaner regularly helps restore the proper mist pattern, improving atomization, fuel efficiency, and acceleration while reducing rough idling caused by uneven fuel delivery.