S-10 Forum banner
1 - 8 of 8 Posts

· Registered
1998 GMC Sonoma SLE
42 Posts
Discussion Starter · #1 ·
My engine is stalling out. I recently replaced the IAC and fixed the MAF issues. Now it will reliably start after stalling where it wouldn't before but it still stalls out. I can't figure out the re learn procedure for the idle air control valve. Does anyone know what it is?

It's a 98 Sonoma v6

· Registered
99 Blazer
480 Posts
Sorry for the large post, but below is the replacement procedure for the IAC. Which I know you don't need, but at the very bottom is the reset procedure. It's obviously very simply and leads me to believe it pretty much just does it automatically. If it doesn't work it looks like you may have other problems.

Idle Air Control Valve Replacement
Removal Procedure
  1. Caution: Refer to
    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.
    For Vehicles equipped with OnStar® (UE1) with Back Up Battery:
    The Back Up Battery is a redundant power supply to allow limited OnStar® functionality in the event of a main vehicle battery power disruption to the VCIM (OnStar®module). Do not disconnect the main vehicle battery or remove the OnStar® fuse with the ignition key in any position other than OFF. Retained accessory power (RAP) should be allowed to time out or be disabled (simply opening the driver door should disable RAP) before disconnecting power. Disconnecting power to the OnStar® module in any way while the ignition is On or with RAP activated may cause activation of the OnStar® Back-Up Battery (BUB) system and will discharge and permanently damage the back-up battery. Once the Back-Up Battery is activated it will stay on until it has completely discharged. The BUB is not rechargeable and once activated the BUB must be replaced.

    in Cautions and Notices.

  2. Disconnect the negative battery cable.

  3. Disconnect the IAT sensor connector.

  4. Disconnect the breather tube from the air cleaner outlet duct.

  5. Remove the wing nut retaining the air cleaner outlet duct.

  6. Loosen the clamp on the outlet of the MAF sensor.
  7. Lift the air cleaner outlet duct from the throttle body and remove the assembly from the MAF sensor.

  8. Disconnect the IAC valve electrical connector.

  9. Remove the IAC valve mounting screws.

  10. Remove the IAC valve and O-ring from the throttle body assembly.
Cleaning and Inspection Procedure
  1. Notice: If the IAC valve has been in service: DO NOT push or pull on the IAC valve pintle. The force required to move the pintle may damage the threads on the worm drive. Also, DO NOT soak the IAC valve in any liquid cleaner or solvent, as damage may result.
  2. Clean the IAC valve O-ring sealing surface, pintle valve seat, and air passage.
    • Remove excess carbon deposits with a small amount of carburetor cleaner on a parts cleaning brush. Follow any instructions on the cleaner container regarding cleaner usage.
    • Do not use a cleaner containing an extremely powerful solvent such as methyl ethyl ketone.
    • Shiny spots on the pintle and seat do not represent a bent or misaligned pintle shaft.
    • If heavy deposits are present in the air passage, remove the throttle body for a complete cleaning. Refer to Throttle Body Assembly Replacement.
  3. Important: Do not reuse the original O-ring.
  4. Replace the IAC valve O-ring.
Installation Procedure

  1. Notice: The IAC valve may be damaged if installed with the cone (pintle) extended more than 28 mm (1-1/8 in). Measure the distance that the valve is extended before installing a new valve. The distance from the idle air control valve motor housing to the end of the idle air control valve pintle should be less than 28 mm (1-1/8 in). Manually compress the pintle until the extension is less than 28 mm (1-1/8 in).
    Important: Use an identical part when installing a new Idle Air Control (IAC) valve. The IAC valve pintle shape and dimensions are designed for specific applications.
  2. On a new IAC valve, measure the distance between the IAC valve pintle and mounting flange. Use finger pressure to slowly retract the pintle if the distance is greater than 28 mm (1–1/8 in).

  3. Lubricate the IAC valve O-ring with clean engine oil.
  4. Align the flange holes with the mounting holes on the throttle body assembly.
  5. Insert the IAC valve through the O-ring into the throttle body assembly.

  6. Notice: Refer to Fastener Notice in Cautions and Notices.
    Important: The screws used to attach the IAC valve are coated with thread locking adhesive. Clean the attaching screw threads and apply thread locking material GM P/N 1052624 or equivalent.
  7. Install the IAC valve mounting screws.
    Tighten the screws to 3 [n-m] (27 lb in).

  8. Connect the IAC valve electrical connector.

  9. Install the air cleaner outlet duct.

  10. Tighten the air cleaner outlet duct wing nut.
  11. Secure the air cleaner outlet duct to the MAF sensor.
    Tighten the air cleaner outlet duct clamp to 4 [n-m] (35 lb in).

  12. Connect the breather tube to the air cleaner outlet duct.

  13. Connect the IAT sensor connector.
  14. Connect the negative battery cable.
  15. Perform the following steps to reset the IAC valve pintle position:
IAC Valve Reset Procedure
  1. Turn ON the ignition for 20 seconds.
  2. Turn OFF the ignition for 10 seconds.
  3. Start the engine.
  4. Check for the proper idle speed.

· Registered
99 Blazer
480 Posts
note that for the above reset procedure: as a precursor, they did have you disconnect the battery for the length of the procedure then reconnect it prior to the reset procedure's first step
That is an excellent thing to point out that most people disregard/don't do! You're exactly right. This reset likely is dependant on the battery being disconnected prior to doing.
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.