Throttle Body

Fig. 5 Two barrel throttle body assembly:

Fig. 6 Single barrel throttle body assembly:

Fig. 7 Single barrel throttle body assembly:

The throttle body is used to regulate the amount of air entering the engine. The throttle body used on Civic, CRX and 1985 Accord models is a two barrel, side draft type with the primary air horn at the top, Fig. 5. The progressive linkage used on these models provides sequential opening of the throttles to allow quick throttle response and improved economy. The throttle body used on 1986--88 Accord and Prelude models is a single barrel, side draft type, Figs. 6 and 7.
On both types of throttle body, coolant is passed through the lower portion to aid warm-up and to prevent icing of the throttle valves and air horn walls. A throttle sensor, attached to the primary throttle valve on two barrel models, senses changes in throttle opening and signals from this sensor are directed to the system control unit. A dash pot is used on most models to slow movement of the throttle valve as it approaches the fully closed position.
The closed throttle position is determined by a throttle stop screw which is preset during manufacture. As the closed throttle position cannot be adjusted, an air bypass channel is included in the throttle body to allow for base idle speed adjustment. Air flow through this bypass channel is controlled by an adjustable needle valve. The idle control system includes an additional group of bypass channels which allow air to bypass the throttle plate. Airflow through these channels is regulated by electronically controlled solenoid valves which allow the PGM-FI system controller to control curb and fast idle speeds.