Easy to understand guide on how an automotive engine throttle actuator and throttle body with IAC valve work, this information pertains to most vehicles.
A throttle actuator and throttle body are generally the same part, the actuator is fully computerized (no cable) with no IAC (idle air control) valve. These devices control the volume or amount of air that enters the engine via the driver's accelerator pedal.
A throttle actuator is held to the intake manifold using three or four bolts
sealed with a gasket, a computer wiring harness connector is directly plugged into
the actuator.
Coolant hoses are used to transfer heat into the actuator to help warm the intake
air for better economy.
A condition called "coking" occurs after miles of usage and should be cleaned
to restore the actuator performance. (Coking can cause hard starting, high or low
idle.) Learn
more
A throttle actuator must open and close freely, if rough spots exist in its operation
it must be replaced.
On older vehicles an idle air control (IAC) valve is used to control idle speed
via the computer, there is no adjustments on either style of throttle body configurations.
This design requires a throttle position sensor (TPS) which provides throttle butterfly
position data for the computer.