GM Truck Club
THE PREMIER CHEVY TRUCK & SUV FORUM
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Results 1 to 4 of 4

Hybrid View

  1. #1

    Default high idle..what else besides throttle body gasket

    I started by 89 suburban (350) after is sat for a week and it is idling very high probably 2500+rpm (don't have a tach). Never has this before

    popping the gas doesn't bring it down. A vacuum leak would make it idle rough, not high, right?

    I haven't had time to check much, but any other things I should check besides vacuum leaks?

    Any ideas would be great thanks.

  2. #2
    Legend unplugged's Avatar
    Join Date
    Sep 2006
    Location
    High Deserts of SoCal
    Posts
    2,554

    Default Test for a leak

    I wouldn't rule out vacuum leaks. Get out the carb cleaner and spray it around the base of the carb/throttle body and at the intake manifold gasket areas. Some prefer to use propane for this test. I like to take the air cleaner off and cup my hands over the air intake. If as I progressively choke off the airflow the idle normalizes, a vacuum leak is indicated.
    There is no way to happiness....happiness is the way.:yipi:
    http://kx6ijq.blu.livefilestore.com/y1pcOFVNH4ix1hjyGUVyXK5LRfef7qSeWzlZDorpQhIEfkZ2ZA  _vXMYypuKMJFw671uF2ZPhjez_j-atRmcjM2zQKpQi1JSsB75/burb1.JPG
    High Desert SoCal
    93 K1500 burb (personal) 350 AT 3" Lift 250K+
    02 Honda Civic LX
    Looking for a 1990's Miata for an engine swap

  3. #3

    Default

    The idle air control motor could be stuck or the passage could be contaminated. To check, pull the air cleaner assy off, and look at the passenger rear of the throttle body. You'll see a 4-wire square plug sticking out at a 45 degree angle, and a hole inside the throat of the body in that corner. If you plug that hole with your finger, the truck should die. If not, a vacuum leak is your issue.

  4. #4

    Default

    Thanks Racer!

    I was wondering where the IAC valve is on these throttle bodies. I will check when I get home. The contamination might be possible becuase I had the air cleaner off while the truck was sitting before this high-idle started.

Similar Threads

  1. Replies: 4
    Last Post: 07-25-2010, 10:17 PM
  2. 87 C10 Holley Throttle Body to Edelbrock gasket leaks
    By cyberpine in forum Chevy C/K Truck Forum
    Replies: 5
    Last Post: 02-04-2010, 04:32 PM
  3. High Idle
    By Chevyguy in forum GM Powertrain
    Replies: 5
    Last Post: 11-12-2007, 01:58 PM
  4. how to change throttle body gasket
    By 89suburban350 in forum Chevy Suburban Forum (GMC Yukon XL)
    Replies: 5
    Last Post: 07-17-2007, 07:40 AM
  5. idle way high
    By 89suburban350 in forum Chevy Suburban Forum (GMC Yukon XL)
    Replies: 6
    Last Post: 07-16-2007, 11:22 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •