Pontiac Fiero 1984-1988 Repair Guide

Idle Air Control (IAC) Valve

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The Idle Air Control (IAC) valve is mounted on the throttle body assembly and provides a constant idle speed regardless of engine loads or driving conditions. The IAC valve controls the amount of air that enters the engine by the way of a ECM signal.

REMOVAL & INSTALLATION



2.5L Engine
1984-86 MODELS
  1. Disconnect the negative (-) battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Remove the Idle Air Control Valve (IAC) electrical connector.
  6.  
  7. Using a 1 1 / 4 in. wrench, remove the IAC valve from the throttle body.
  8.  

Before installing a new IAC valve, measure the distance that the conical valve (pintle) extends. The measurement should be made from the valve housing to the end of the pintle cone. The distance should be no greater than 1 1 / 8 inch (28mm). If the pintle cone is extended too far, damage to the IAC valve may occur when installed.

1987-88 MODELS

The IAC valve is flange mounted, with a dual taper and 10mm diameter pintle. If replacement is necessary, only an IAC valve with the correct part No. having the correct pintle shape and size may be used.

  1. Disconnect the negative (-) battery cable.
  2.  
  3. Remove the IAC valve electrical connector.
  4.  
  5. Remove the two attaching screws and the IAC valve.
  6.  


WARNING
Under no circumstances should the valve pintle be tampered with by hand, screwed or pushed in, or pulled out because damage may result.

To install:

  1. Lubricate the new O-ring seal with automatic transmission fluid and install on the IAC valve.
  2.  
  3. Install the IAC valve to the throttle body.
  4.  
  5. Coat the two IAC valve attaching screws with thread locking compound and torque to 28 inch lb. (3.2 Nm).
  6.  
  7. Install the IAC electrical connector. Reconnect the negative (-) battery cable.
  8.  
  9. Start the engine and allow to reach operating temperature. Check the idle speed with a tachometer.
  10.  

2.8L Engine


Click image to see an enlarged view

Fig. Fig. 1 The Idle Air Control (IAC) valve is threaded into the throttle body

  1. Disconnect the negative (-) battery cable.
  2.  
  3. Remove the air duct assembly.
  4.  
  5. Remove the IAC valve electrical connector.
  6.  
  7. Using a 1 1 / 4 inch wrench, remove the IAC valve from the throttle body.
  8.  

To install:

  1. With a new gasket, install the IAC valve into the throttle body and torque to 13 ft. lbs. (18 Nm).
  2.  
  3. Reconnect the IAC electrical connector.
  4.  
  5. Install the air duct and connect the negative (-) battery cable.
  6.  
  7. Start the engine and allow the engine to reach operating temperature and normal idle speed. Check to see if the idle speed is to specifications using a tachometer.
  8.  

ADJUSTMENT



Type 1

Exert firm pressure on the conical valve (pintle cone) to retract it. A slight side to side movement may be helpful.

Type 2


Click image to see an enlarged view

Fig. Fig. 2 Two types of Idle Air Control (IAC) valve used



Click image to see an enlarged view

Fig. Fig. 3 When unplugging the Throttle Position Sensor (TPS) be careful not to break the locktab

  1. Compress the retaining spring from the conical valve (pintle cone) while turning the valve IN with a clockwise motion. The return spring should be in the original position with the straight portion of the spring end aligned with the flat surface of the valve.
  2.  

To install:

  1. With a new gasket, install the IAC valve into the throttle body and torque to 13 ft. lbs. (18 Nm).
  2.  
  3. Reconnect the IAC electrical connector.
  4.  
  5. Install the air cleaner and connect the negative (-) battery cable.
  6.  
  7. Start the engine and allow the engine to reach operating temperature and normal idle speed. Check to see if the idle speed is to specifications using a tachometer.
  8.  

 
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