GM Full-Size Trucks 1980-1987 Repair Guide

Idle Air Control Valve


See Figures 1 and 2

All engines except the 454 use a thread type IAC valve. The 454 is equipped with a flange type IAC valve which is attached with screws.

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Fig. Fig. 1: Thread type IAC valves, TBI 220

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Fig. Fig. 2: Flange type IAC valve, TBI 220


  1. Remove the air cleaner.
  3. Disconnect the electrical connector from the idle air control valve.
  5. On the threaded type, use a 1 1 /4 in. (32mm) wrench or tool J-33031, remove the idle air control valve.
  7. On the 454 engine, remove the retaining screws and remove the IAC valve.

Before install a new idle air control valve, measure the distance that the valve extends (from the motor housing to the end of the cone); the distance should be no greater than 11/ 8 in. (28mm). If it extends too far, damage will occur to the valve when it is installed.

  1. To adjust the threaded type without a collar compress the valve retaining spring, while turning the valve "in". On all others, exert firm pressure, with slight side to side movement, on the pintle to retract it.
  3. To complete the installation, use a new gasket and reverse the removal procedures. Start the engine and allow it to reach operating temperature.

The ECM will reset the idle speed when the vehicle is driven at 30 mph.