The throttle body is a housing with a valve that regulates airflow into an engine’s intake manifold. The throttle body resembles the base of a carburetor, and some low-cost fuel-injection systems had one or two injectors inside the throttle body instead of an injector for each cylinder, and that was where air mixed with fuel. On multi-point injection systems, with one or more injectors for each cylinder, only air passes through the throttle body. Many drivers think “wide-open throttle” means flooring the gas pedal. That’s correct, but flooring the pedal opens a throttle blade as wide as it can go, allowing more air into the engine. When more air goes in, more gas (or diesel) goes into the engine with it, producing more power and speed. Dirt can build up in a throttle body and cause sluggish acceleration, hard starting or stalling, so the body needs to be cleaned as part of fuel system maintenance.
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