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IAC Valve Cleaning

Discussion in '80-Series Tech' started by Scamper, Aug 18, 2003.

  1. Scamper

    Scamper

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    My wife has been complaining about the idle being a tad rough ever since the head gasket was replaced. Yes, it's not smooth as glass the way it used to run, but I've never felt as if there was any problem with it stalling or conking out.

    So I'm installing a new set of wires on it yesterday, and decided to pull the IAC to take a gander. I found that the plunger end was pretty well encrusted with carbon deposits that made it look as if it couldn't possibly seal well against the mating surface. No mention in the BGB of any maintenance on this other than checking it's function. Some soft cloth and carb cleaner made it look as good as new. Wife says it's running better now, but I don't know if it was the wires or the IAC, or both.

    Question: would a dirty IAC have caused the rough idle? Seems like a silly question for a part called an IAC valve, but thought I'd ask.

    Tom
     
  2. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Idle air control...........


    If the passage or the tip of the plunger is fouled, I can see how the ammount of air passed through would be difficult to meter consistantly. As this air-bleed controls the idle speed it's easy to see the relationship. It is also possible that you had one or more edgy plug wires that were disturbed when the head was removed. It sounds like it was the IAC to me, if the idle was "hunting" as opposed to "dropping" a cylinder occasionaly. It's difficult to say for certain when you change more than one thing at a time. :-\ If you were dropping a cylinder I think the OBDII may pick that up and store it.
     
  3. Scamper

    Scamper

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    Hi Dan,

    I originally though the monkeys in the shop just tugged too hard on the wires when they did the head which was causing the roughness. Hence my request for wires a while ago.

    But as I was perusing the manual, I came upon the IAC and thought I'd give it a look. What puzzles me is that the roughness came immediately after I reached the zenith of my "quest for power" and subsequent repair, and the carbon buildup had certainly been their since the Jurasic period. So in theory, the roughness should have been there all along...

    Odd that they don't tell you to clean this if it effects the truck like that--it's only a 1/10th :banana: job.
     
  4. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Tom,

    I too noticed a difference in my idle habits when I installed my blower, I think some of it stems from the increased distance between the throttle body and the cylinders.
     
  5. cruiserman

    cruiserman

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    [quote author=Scamper link=board=2;threadid=4410;start=msg32957#msg32957 date=1061225225]

    Odd that they don't tell you to clean this if it effects the truck like that--it's only a 1/10th :banana: job.
    [/quote]That banana gets a lot bigger when the IAC valve mounting bolts are buggered.
     
  6. Scamper

    Scamper

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    I know what you mean. When I went to pull it off, I was wondering to myself why on earth they would have used phillips head screws to hold it on. I was thinking of replacing them with hex heads, but didn't have any the right size, so I just made sure to put some anti-sieze on before reinstalling.
    Tom