I30 1996-1997

Idle Air Control Valve

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Operation



Specific to:

Infiniti G20 1996, 1999-2002

Infiniti G35 2003-2005

Infiniti I30 1996-2001

Infiniti I35 2002-2004

Infiniti M45 2003-2004

Infiniti Q45 1996-1997

The Idle Air Control (IAC) system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine adjustment of the amount of air which by-passes the throttle valve via the Idle Air Control Valve (IACV) and Auxiliary Air Control (AAC) valve. The IACV-AAC valve changes the opening of the air by-pass passage to control the amount of auxiliary air. This valve is actuated by a step motor built into the valve, which moves the valve in the axial direction in steps corresponding to the ECM output signals.

One step of the IACV-AAC valve movement causes the respective opening of the air by-pass passage. When the step advances, the opening is enlarged. The opening of the valve is varied to allow for optimum control of the engine idling speed. The camshaft position sensor detects the actual engine speed and sends a signal to the ECM. The ECM then controls the step position of the IACV-AAC valve so that the engine speed coincides with the target value memorized in the ECM. The target engine speed is the lowest speed at which the engine can operate steadily. The optimum value stored in the ECM is determined after taking into consideration various engine conditions, such as during warm up, deceleration, and engine load (air conditioner, power steering, and cooling fan operation).

Removal & Installation



Specific to:

Infiniti I30 1996-2001

The manufacturer does not provide a specific removal and installation procedure for this component. Use the illustration as a guide when servicing this component.

Perform the learn procedure if the IAC has been replaced, refer to Reset Procedure.

Click image to see an enlarged view

Fig. Idle Air Control (IAC) Valve location-I30

Reset Procedure



Pre-Conditioning

Specific to:

Infiniti G20 1996, 1999-2002

Infiniti I30 1996-2001

  1. -Idle Air Volume Learning- is an operation to learn the idle air volume that keeps each engine within a specific range. It must be performed under any of the following conditions:

    Each time the IACV-AAC valve, throttle body, or ECM is replaced
     
    Idle speed or ignition timing is out of specification
     

  2.  
  3. Before performing -Idle Air Volume Learning,- make sure that all of the following conditions are satisfied. Learning will be cancelled if any of the following conditions are missed for even a moment:

    Battery voltage: More than 12.9 volts (at idle)
     
    Engine coolant temperature: 158-203°F (70-95°C)
     
    PNP switch: ON
     
    Electric load switch: OFF (Air conditioner, headlamp, rear window defogger-on vehicles equipped with daytime running light systems, if the parking brake is applied before the engine is started, the headlamps will not be illuminated)
     
    Cooling fan motor: Not operating
     
    Steering wheel: Neutral (Straight-ahead position)
     
    Vehicle speed: Stopped
     
    Transmission: Warmed-up
     

  4.  
  5. For A/T models with CONSULT-II, drive vehicle until the -FLUID TEMP SE- in the -DATA MONITOR- mode of the -A/T- system indicates less than 0.9 volts.
  6.  
  7. For A/T models without CONSULT-II and M/T models, drive vehicle for 10 minutes.
  8.  

Problem With Reset Procedure

Specific to:

Infiniti G20 1996, 1999-2002

Infiniti I30 1996-2001

  1. If the idle air volume learning cannot be performed successfully, proceed as follows.
  2.  
  3. Before servicing the vehicle, refer to the Precautions Section.
  4.  
  5. Check that the throttle valve is fully closed.
  6.  
  7. Check that downstream of the throttle valve is free from air leakage.
  8.  
  9. Adjust the closed throttle position switch and reset the memory.
  10.  
  11. When the above items are OK, check engine component parts and their installation condition for faults.
  12.  
  13. Repair the cause of the problem.
  14.  
  15. If any of the following conditions occur after the engine has started, eliminate the cause of the problem and perform -Idle Air Volume Learning- Reset Procedure again:

    Engine stalls
     
    Erroneous idle
     
    Blown fuses related to the IACV-AAC valve system
     

  16.  

With Consult-II

Specific to:

Infiniti G20 1996, 1999-2002

Infiniti I30 1996-2001

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition switch ON and wait at least 1 second.
  4.  
  5. Turn the ignition switch OFF and wait at least 10 seconds.
  6.  
  7. Start the engine and warm it up to the normal operating temperature.
  8.  
  9. Check that all items listed under the topic -PRE-CONDITIONING- are in good order.
  10.  
  11. Turn the ignition switch OFF and wait at least 10 seconds.
  12.  
  13. Start the engine and let it idle for at least 15 seconds.
  14.  
  15. Select -IDLE AIR VOL LEARN- in the -WORK SUPPORT- mode.
  16.  
  17. Touch -START- and wait 15 seconds.
  18.  
  19. Make sure that -CMPLT- is displayed on the CONSULT-II screen. If -INCMP- is displayed, -Idle Air Volume Learning- will not be carried out successfully. In this case, find the cause of the problem by referring to the section, Problem With Reset Procedure.
  20.  
  21. Rev up the engine 2-3 times. Make sure that idle speed and ignition timing are within specification.
  22.  

Without Consult-II

Specific to:

Infiniti G20 1996, 1999-2002

Infiniti I30 1996-2001

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition switch ON and wait at least 1 second.
  4.  
  5. Turn the ignition switch OFF and wait at least 10 seconds.
  6.  
  7. Start the engine and warm it up to the normal operating temperature.
  8.  
  9. Check that all items listed under the topic -PRE-CONDITIONING- are in good order.
  10.  
  11. Turn the ignition switch OFF and wait at least 10 seconds.
  12.  
  13. Start the engine and let it idle for at least 15 seconds.
  14.  
  15. Disconnect the throttle position sensor harness connector (brown), then reconnect it within 5 seconds.
  16.  
  17. Wait 15 seconds.
  18.  
  19. Make sure that the idle speed is within specification. If not, the result will be incomplete. In this case, find the cause of the problem by referring to the section, Problem With Reset Procedure.
  20.  
  21. Rev up the engine 2-3 times. Make sure that idle speed and ignition timing are within specification.
  22.  

Testing



Specific to:

Infiniti G20 1996, 1999-2002

Infiniti I30 1996-2001

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Make sure the battery voltage is more than 11 volts at idle.
  4.  
  5. The temperature must be above 14°F (-10°C).
  6.  
  7. Open the engine hood.
  8.  
  9. Start the engine and warm it up to normal operating temperature.
  10.  
  11. Turn the ignition switch OFF and wait at least 10 seconds.
  12.  
  13. Turn the ignition switch ON again and select -DATA MONITOR- mode with the CONSULT-II.
  14.  
  15. Start the engine and run it for at least 1 minute at idle speed.
  16.  
  17. Ensure that specifications are met.
  18.  

 
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