Throttle Body: Description and Operation

Fig. 3 Electronic fuel injection component location. V6-183 engine:

Fig. 12 Throttle body assembly. V6-177 engine (4-140 engine similar):

Fig. 13 Throttle body assembly. 6-300 engine:

Fig. 14 Throttle body assembly. V8-302 engine:

Air flow to the engine is controlled by the throttle body through a single butterfly-type valve on 4-140 and V6-177 engines, Fig. 12, or a double butterfly-type valve on 6-300 and V8-302 engines, Figs. 13 and 14. On V6-183 engine, the throttle body and air intake assembly is a single piece aluminum casting, Fig. 3. Throttle position is controlled by multi-link, progressive opening, throttle linkage. The throttle body has a single bore on 4-140, V6-177 and 183 engines and a dual bore on 6-300 and V8-302 engines with an air bypass channel around the throttle plate. The bypass channel controls both cold and warm engine idle air flow which is regulated by an air bypass valve assembly mounted on the air cleaner on 4-140 engines, the upper intake manifold on V6-177 and 183 engines and on the throttle body on 6-300 and V8-302 engines. The air bypass valve is controlled by the EEC computer and incorporates a linear actuator which positions a variable area metering valve.