Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

What would cause an IAC to drop from 30 steps to ZERO?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BurbinOR, Jun 28, 2004.

  1. BurbinOR

    BurbinOR 3/4 ton status

    Joined:
    Feb 17, 2000
    Posts:
    5,829
    Likes Received:
    0
    Location:
    Oregon
    And with it comes rough idle, no big deal but something isn't right. I see the counts on my Auto Xray scanner and no rhyme or reason as to why it happens, and is sporadic. This on an 89 Jimmy with the 4.3L V-6.

    /forums/images/graemlins/confused.gif
     
  2. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    Is zero fully closed? If so, then you need to look at some of the other data and watch what it does just before the IAC goes to zero. If zero is fully closed, then the computer thinks that one of two possiblities is happening. First, a flaky TPS could be causing the ECM to think that you have stepped on the throttle, so it closes the IAC. Second, for some reason the ECM thinks that the idle has increased, so it closes down the IAC to being the idle back into spec. If it's the second, then finding the cause could be real fun. /forums/images/graemlins/wink.gif
     
  3. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    Just a few things to ckeck out
    Vacume leak. Stuck/bad EGR. Check the TB base gasket for leak. PVC valve.
     

Share This Page