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Unexplained high rpm

Discussion in '308/328' started by GTB Dave, Sep 22, 2019.

  1. GTB Dave

    GTB Dave Karting
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    Nov 3, 2013
    112
    B.C. Okanagan
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    Dave
    Hello, a little puzzled here. My ‘82 injected 308 is well maintained, in top shape, and has been running flawlessly. It’s been parked it in my garage for the last two weeks after a nice afternoon drive. Went out this evening to take it for a spin, and when it lit, the idle jumped immediately to a little over 4K on start up. The linkage is not binding, the throttle plate is not stuck open, can’t seem to find any hoses disconnected that would be creating a vacuum leak either. Just seems odd to go from running like a champ to this. Any ideas?
    -Dave.
     
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  3. rjlloyd

    rjlloyd Formula Junior
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    Jun 19, 2014
    311
    Brisbane, Australia
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    Richard Lloyd
    Possibly the deceleration valve stuck open, you may have to systematically start crimping/blanking vacuum lines to see if you bring the idle back to normal to identify the cause Image Unavailable, Please Login


    Sent from my iPhone using FerrariChat
     
  4. jdjagguy

    jdjagguy Rookie

    Sep 11, 2007
    29
    Enid Oklahoma
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    Richard Crump
    The floor mat isn't jammed into the throttle pedal is it?
    RC
     
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  5. GTB Dave

    GTB Dave Karting
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    Nov 3, 2013
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    No, first thing I checked. Thanks!
     
  6. GTB Dave

    GTB Dave Karting
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    Nov 3, 2013
    112
    B.C. Okanagan
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    Dave
    Thanks, I’ll start there. I think I have a spare valve in my parts stash. Thanks for the help!
     
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  8. Vonbarron

    Vonbarron Formula Junior
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    Aug 26, 2014
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    Sammamish Washington
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    S Barron
    You coming down Saturday?
     
  9. GTB Dave

    GTB Dave Karting
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    Nov 3, 2013
    112
    B.C. Okanagan
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    Dave
    Unfortunately no, I won’t be able to make it.
     
  10. Vonbarron

    Vonbarron Formula Junior
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    Aug 26, 2014
    939
    Sammamish Washington
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    S Barron
    Shoot, I need a sucker monkey for the sidecar
     
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  11. miketuason

    miketuason F1 World Champ
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    Feb 24, 2006
    14,220
    Cerritos, CA.
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    Mike
    Vacuum leak will also make the idle go up as it sucking extra air.
     
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  13. thorn

    thorn F1 Rookie
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    Aug 7, 2012
    2,889
    Tallahassee, FL
    Agreed. Try a propane test.
     
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  14. GTB Dave

    GTB Dave Karting
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    Nov 3, 2013
    112
    B.C. Okanagan
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    Dave
    Got it sorted. Couldn’t find any vacuum leaks, swapped out to my spare deceleration valve with no change. During all of this it did idle well at one point for 30 seconds or so then jumped back to around 3700 rpm. Looking at the motor scratching my head a little, I noticed that the engine wiring harness plug seemed to be slightly unplugged. Upon further inspection it indeed was. One of the side clips that hold it together had broken. I pushed the plug back into its receptacle and voila!! The car runs like a champ once again. I’ve secured it temporarily, but now have to source a new plug end somewhere. Thanks for your guys input. I appreciate it. Cheers, Dave.
     
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  15. miketuason

    miketuason F1 World Champ
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    Feb 24, 2006
    14,220
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    Mike
    What does this plug looks like and where is it located, can you post pic?
     
  16. GTB Dave

    GTB Dave Karting
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    Nov 3, 2013
    112
    B.C. Okanagan
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    Dave
    Both the male and female parts of the plug assembly are a white / opaque color, 8 pin if I remember correctly. I’ll double check that when I go take a pic shortly. It’s located beside the ignition coils / top shock mount area. I’ll try and post a picture in a bit.
     
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