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QV very fast cold idle

Discussion in 'Mondial' started by wsendelback, Jul 20, 2023.

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  1. wsendelback

    wsendelback Rookie

    May 12, 2016
    31
    Dallas, TX
    Full Name:
    William Sendelback
    #1 wsendelback, Jul 20, 2023
    When I start cold my '84 QV, the idle jumps to 2800 RPM until the car warms up. The workshop manual points to a :"warm-up regulator" located on the right side of the throttle body that provides fast cold idle. And I found in my owner's manual that on cold start, the fast idle should be 2800 RPM plus or minus 300 RPM until the water temp reaches 120 F. That seems excessive in my opinion. I would much prefer 1500 RPM cold fast idle. But there appears to be no fast idle adjust on the warm-up regulator. Have others seen and questioned this very fast cold idle? And have others found a way to reduce the very fast cold idle?
     
  2. theunissenguido

    theunissenguido F1 Rookie
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    Jan 21, 2004
    2,664
    Argent/Brasil
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    Guido
    #2 theunissenguido, Jul 21, 2023
    Did you already disconnect cold start system ? For Texas it is not needed.
     
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,769
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    #3 Steve Magnusson, Jul 21, 2023
    The Warm-Up Regulator (WUR) only adds enrichment when cold (it doesn't raise the engine idle RPM). On a 1984 US QV, the Auxiliary Air Valve (AAV) is what allows extra air into the engine when cold to raise the cold idle RPM. You can try blocking (pinching closed) one of the large air lines of the AAV to see if this drops the cold idle RPM significantly.

    On a 1983 US QV, in addition to the AAV, there is another device (the Cold Start Air Valve) that lets in a lot of air when cold and (intentionally) results in a crazy high cold idle RPM of like 2800 RPM -- are you sure that you don't have a 1983 US QV, and are reading a 1983 US QV OM? What is the print number of the OM that you have -- it will be in the format of XXX/YY (usually on the title page or last page). Or post a picture of your engine bay -- on a 1983 US QV, the fuel distributor will be silver; on a 1984 US QV, the fuel distributor will be black.
     
  4. wsendelback

    wsendelback Rookie

    May 12, 2016
    31
    Dallas, TX
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    William Sendelback
    #4 wsendelback, Jul 22, 2023
    Thanks, gents. Steve, my OM is, in fact, an '83 issue. However, my QV cab is an '84. The label for the catalytic combustor in the engine compartment says it is an '84, and the metal specs label on the driver's side door jam says the car was produced in April, 1984. My fuel distributor is neither silver nor black, but instead is a dirty, silvery medium blue. Confusing.

    I will try pinching closed one of the large air lines on the AAV. My buddies at Norwood Auto Italia made the same suggestion.

    No, I have not disconnected the cold start system. As you suggest, with days consistently 100 degrees plus here in Dallas, a cold start system is not needed. Any suggestions on how to make that disconnection? .
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,769
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #5 Steve Magnusson, Jul 22, 2023
    That is a bit weird -- have you tried decoding your VIN at https://www.red-headed.com/vin.html ?

    A 1983 US QV OM will not apply to a 1984 US QV as the 1983 US QV is K-Jet without Lambda (and has a cold start air valve) while the 1984 US QV is K-Jet with Lambda (which does not have a cold start air valve).

    Engines can, and do, get "transplanted" sometimes so please post some engine bay photo(s) if you can.
     
  6. wsendelback

    wsendelback Rookie

    May 12, 2016
    31
    Dallas, TX
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    William Sendelback
    #6 wsendelback, Jul 22, 2023
    VIN checks out in all aspects. Says car is '84. Will try to post engine pix..
     
  7. Alden

    Alden F1 Rookie
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    Apr 25, 2010
    3,596
    Central Florida
    #7 Alden, Jul 23, 2023
    I was advised the disconnecting the cold start system was as simple as unplugging the electrical connection to the 9th injector located on the right side of the intake plenum, that's the way it is on my 88 3.2, yours might be different. Before you ask, the large black hose looping around the front and back of the engine. A fire suppression system, the Volkswagen van guys, we use it, and since I had lotus way back in the day that caught fire and tried to kill me I thought it was a good idea, lol.
    Image Unavailable, Please Login
     
  8. wsendelback

    wsendelback Rookie

    May 12, 2016
    31
    Dallas, TX
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    William Sendelback
    #8 wsendelback, Aug 5, 2023
    Thanks, gents. Solved the problem. Should have thought of this early on since the accelerator cable seemed sticky. Ended up thoroughly cleaning the throttle body and throttle plate with carb cleaner, and that took care of it and the very fast cold idle problem. Runs and idles great. Like I said, I should have thought of this sooner. Also, Steve, my fuel distributor had been replaced before I bought the car, hence the blue color rather than the black or silver you suggested.
     
    moysiuan likes this.
  9. Alden

    Alden F1 Rookie
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    Apr 25, 2010
    3,596
    Central Florida
    #9 Alden, Aug 12, 2023
    For everyone else, don't forget about the "Mondial cruise control carpets" that slide up against your accelerator pedal and give you more rpms than you expected, lol
     

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