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328 Throttle Body

Discussion in '308/328' started by pad, Aug 8, 2023.

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  1. pad

    pad Formula 3

    Sep 30, 2004
    1,426
    Tequesta, FL
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    Paul Delatush
    #1 pad, Aug 8, 2023
    On my '86 328 throttle body there is a 1" long pipe extending downwards from the bottom of the body. What is its purpose? Is there supposed to be hose attached to the pipe and if so, where does the hose go to? The pipe has about a 4mm diameter. On the picture, it is just left of the throttle position switch. Thanks, Paul
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  2. Lawrence Coppari

    Lawrence Coppari Formula 3

    Apr 29, 2002
    2,192
    Kingsport, TN
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    Lawrence A. Coppari
    #2 Lawrence Coppari, Aug 8, 2023
    If memory serves, it connects to the warm-up regulator.
     
  3. pad

    pad Formula 3

    Sep 30, 2004
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    Paul Delatush
    #3 pad, Aug 8, 2023
    You are correct in that the WUR connects to the throttle body. That connection is "before" the butterfly (and I have that connection on my car). The pipe that I am questioning is "after" the butterfly, i.e. on the plenum side of the TB.
     
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  4. Lawrence Coppari

    Lawrence Coppari Formula 3

    Apr 29, 2002
    2,192
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    Lawrence A. Coppari
    #4 Lawrence Coppari, Aug 8, 2023
    Wish I could have helped. I had my 328 plenum off this past spring but cannot remember. I am sure someone else will help you out. I cannot look because I am out of town.
     
  5. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,105
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    Brian Crall
    #5 Rifledriver, Aug 8, 2023
    Look at the vacuum diagram sticker in the engine bay.
     
  6. SeattleM5

    SeattleM5 Formula 3
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    Ettore Palazzo
    #6 SeattleM5, Aug 8, 2023
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  7. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    Steve Magnusson
    #7 Steve Magnusson, Aug 8, 2023
    Vacuum source to operate the cut-off valve of the air injection system on a US version (K-Jet with Lambda) 328 during cold-running (on a euro version 328, K-Jet without Lambda, it would be used for the WUR, but your throttle body looks US version). One thing for sure is that it shouldn't just be left open to atmosphere and let unfiltered air into the engine. Has your air injection system been removed?
     
  8. pad

    pad Formula 3

    Sep 30, 2004
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    Paul Delatush
    #8 pad, Aug 8, 2023
    Thanks for all your replies. It turned out to be the vacuum supply for the air injection system. I was able to find the connecting hose hiding under the Plenum and have reconnected it. Tomorrow I will take the car for a ride and see how it behaves.
     
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  9. ferrariowner

    ferrariowner Formula 3

    Feb 21, 2014
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    Ron
    #9 ferrariowner, Aug 8, 2023
    It will probably run a lot better without the vacuum leak. Unless someone adjusted the CSI inject without knowing.
    Good luck.
     
  10. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #10 Steve Magnusson, Aug 8, 2023
    That's possible, but it's also possible that it could run way worse when warm if the electrovalve has failed (in a way that allows vacuum to always reach the cutoff valve) and plugging the hose back in will (wrongly) turn on the air injection during warm-running (which will mess up the Lambda system operation) -- i.e., someone unplugged that hose to "fix" bad warm-running.
     
  11. miketuason

    miketuason F1 World Champ
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    Mike
    #11 miketuason, Aug 9, 2023
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  12. Sergio Tavares

    Sergio Tavares Formula 3

    Nov 15, 2018
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    Sergio Tavares
    #12 Sergio Tavares, Aug 28, 2023

    Any change?
     
  13. pad

    pad Formula 3

    Sep 30, 2004
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    Paul Delatush
    #13 pad, Sep 7, 2023
    Issues resolved. I've gone ahead and ordered all new vacuum hoses. A project I'll tackle in the future.
     
  14. Kent Dellenbusch

    Kent Dellenbusch Formula Junior
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    Oct 7, 2008
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    #14 Kent Dellenbusch, Sep 8, 2023
    Not a bad drawing actually. I can follow it just fine.
     
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