Cutlass Ciera FWD L4-151 2.5L (1982)
Throttle Body: Description and Operation
The TBI unit is made up of two major castings: a throttle body casting with a throttle valve--to control air flow--and a fuel body assembly which
houses the integral pressure regulator and the fuel injector.
Idle Control & Throttle Position
Devices which control idle speed and provide throttle position are also mounted on the throttle body.
Vacuum Ports
The throttle body contains several vacuum ports to supply vacuum signals to the EGR valve, MAP sensor and canister purge system.
Fuel Injector
The fuel injector is a solenoid operated device controlled by the ECM.
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Incoming fuel is directed to the lower end of the injector assembly--which has a fine screen surrounding the injector inlet.
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When the ECM actuates the solenoid, the normally closed ball valve is lifted off its seat and pressurized fuel is sprayed--in a conical pattern--at
the walls of the throttle body bore--above the throttle valve.
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Excess fuel passes through a pressure regulator and returns to the fuel tank.
Pressure Regulator
The fuel pressure regulator on all systems, and the fuel pressure compensator on the front TBI unit of the "Crossfire" injection system are serviced
as a unit with the fuel meter cover assembly and must not be interchanged from one unit to another.
