Ford Mustang/Capri 1979-1988 Repair Guide

Air Throttle Body Assembly


The throttle body assembly controls air flow to the engine through a single butterfly-type valve. The throttle position is controlled by conventional cable/cam throttle linkage. The body is a single-piece die casting made of aluminum. It has a single bore with an air bypass channel around the throttle plate. This bypass channel controls both cold and warm engine idle air flow control as regulated by an air bypass valve assembly mounted directly to the throttle body. The valve assembly is an electromechanical device controlled by the EEC computer. It incorporates a linear actuator which positions a variable area metering valve.

Other features of the air throttle body assembly include:

An adjustment screw to set the throttle plate at a minimum idle airflow position.
A preset stop to locate the WOT position.
A throttle body mounted throttle position sensor.
A PCV fresh air source located upstream of the throttle plate.
Individual ported vacuum taps (as required) for PCV and EVAP control signals.


See Figure 1

  1. Remove the four throttle body nuts. Make sure that the throttle position sensor connector and the air bypass valve connector have been disconnected from the harness. Disconnect the air cleaner outlet tube.
  3. Identify and disconnect the vacuum hoses.
  5. Remove the throttle bracket.
  7. Carefully separate the throttle body from the upper intake manifold.
  9. Remove and discard the gasket between the throttle body and the upper intake manifold.

If scraping is necessary, be careful not to damage the gasket surfaces, or allow any material to drop into the manifold.

  1. Installation is the reverse of removal. Tighten the throttle body-to-upper intake manifold nuts 12-15 ft. lbs.

Click image to see an enlarged view

Fig. Fig. 1: Air throttle body and upper intake manifold assemblies-4-140 engine