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High idle and booster question

Discussion in '40- & 55-Series Tech' started by UGLY88, Dec 12, 2003.

  1. UGLY88


    Likes Received:
    Oct 21, 2003
    Be prepared for a long post.

    Background: This vehicle has a new starter, alternator, fuel filter and complete tune up(plugs, wires, cap, rotor) with in the last two weeks.

    It was around zero degrees F last night. This morning I start the 62 up and it starts great! however the high idle kicks in and it is no big deal right? Well the high idle starts to fluctuate a lot like it can't decide if it is warming up or not. the fluctuations started almost imediately with in 1 minute after startup. So I let it go, not knowing if this is normal, and it keeps doing this? Once it gets warm it idles down to the appropriate 600 rpms. Then When I drive it and put it in park the idles shoots up to 900-1500 depending on how it feels that day? So what gives with the fluctuating high idle? Is there a temp sensor that is going bad?
    As far as the high idle goes after driving I assume my "TPS" needs a check and adjustment? However could a Leaky Brake booster cause a high idle situation? HOw do I tell if the booster is leaking? WHen I go to stop I stop fine but if I let up on the brake once then aply again I get more posotive feel. There are no leaks in the system so is my booster bad or do my rear brakes just need adjustment?
    I think that makes a short story long so can anyboddy help me out? I am fairly mechanicaly sound where I have built engines bfore, but When it comes to modern vacuum and idle circuits I am just trying to catch up. Thanks for you help so far and look forward to a lot of responses.

    -Seth in Wisconsin
  2. 60wag

    60wag SILVER Star

    Likes Received:
    Jun 25, 2003
    Boulder, CO
    A common problem on 60s, not sure about 62s, is the fitting that attaches the brake booster vacuum hose to the intake manifold becomes blocked. Its a steel thing with discs welded to it that look like a heat sink. It unscrews from the manifold. Clean it out with a wire or a small drill. This might help the power brake assist when pushing the pedal repeatedly. HTHs Can't help with the idle problem.
  3. fsusteve


    Likes Received:
    Aug 2, 2003
    Naples/Big Pine Key, Fl
    Can't think of the name of the thing (high idle solenoid?) kicks on when the a/c is turned on. I know you're NOT running the a/c but it could be this solenoid? going bad. Maybe Poser, Hammerhead will know.