What Is a Throttle Body?
What Is a Throttle Body? Internal combustion gasoline engines require three things to operate: oxygen, fuel and a spark. On modern engines, fuel delivery and spark timing are handled by a computer controlled system of pumps and actuators. Air delivery is a bit more analog, which is where the throttle body comes in. Function Throttle bodies are essentially air valves, and can take a number of forms. Most are butterfly valves, but barrel-type and pinch valves have also been used. Jupiterimages/Comstock/Getty Images Precedents Prior to fuel injection, air delivery was modulated by a set of butterfly valves set into the base of an engine's carburetor. Paulbr/iStock/Getty Images MFI Throttle Bodies Most engines use Multi-Point Fuel Injection (MFI.) In these systems, the throttle body is responsible only for modulating air delivery. Pawel Gaul/iStock/Getty Images TBI Systems Many older engines use Throttle Body Injection (TBI.) These throttle bodies r...