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84 308 qv auxiliary air valve & fast idle

Discussion in '308/328' started by jimmyp11, Nov 28, 2020.

  1. jimmyp11

    jimmyp11 Rookie

    Dec 25, 2019
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    jim patterson
    I have read the posts by Birdman and others about eliminating the fast idle on a cold start on the 2v and earlier cars. Is this possible on the 308 qv? I'm down here in south FL and I doubt it needs to sit at 2K for 60-90 seconds.

    Thanks
    jim
     
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  3. Steve Magnusson

    Steve Magnusson F1 World Champ
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    #2 Steve Magnusson, Nov 28, 2020
    Last edited: Nov 28, 2020
    1980-1983 US 308 have an AAV and a cold start air valve (it's the cold start air valve that gives the ridiculously high ~3K cold idle RPM and which people often remove).

    1984-85 US 308 only have an AAV so don't usually report such a high cold start idle RPM (especially in a warm climate like FL).

    Few things you might do IMO:

    1. Check the Bosch PN on your existing AAV -- might have been wrongly changed to something that looks about right, but isn't the correct one.

    2. Measure the voltage between the two wires going to the AAV (and confirm that it is plugged in ;)) -- should be +12V DC whenever the engine is running.

    3. Measure the resistance between the two terminals of the unplugged AAV (engine not running) to confirm/deny if the internal heater coil is intact -- should be some sort of fairly lowish resistance (10s~100s?) and not infinite Ohms.

    2K RPM cold idle isn't crazy, but it is high-ish for a warm climate and the time you report it persists does seem on the long-ish side.
     
  4. jimmyp11

    jimmyp11 Rookie

    Dec 25, 2019
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    jim patterson
    Thanks I will do that. Well . . .its more like 45 sec. When your sitting there waiting for it to quit, 45 sec seems longer LOL

    So I take it I cant do any trick like the 80-83 with the air valve? I just need to let it do its "thing"?

    jim
     
  5. Steve Magnusson

    Steve Magnusson F1 World Champ
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    If you pass the three tests above, the next thing to do would be to confirm that it is correctly fully closing when warm (the oven test):

    If it is not closing when warm, it should really be replaced (and this would require retweaking things as, if it is still passing air when warm, when that is corrected, the warm idle will be reduced).

    If it is closing when warm and the only "problem" is that it is opening too much when cold, you can place a fixed orifice in one of the air lines to limit how high the cold idle goes (i.e., the area of the hole in the fixed orifice is made smaller than the AAV area open when cold).
     
  6. thorn

    thorn F1 Rookie
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    Aug 7, 2012
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    Tallahassee, FL
    What is your warmed-up idle RPM? Both with, and without a load?
     
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  8. jimmyp11

    jimmyp11 Rookie

    Dec 25, 2019
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    jim patterson
    right at 900 rpm
     
  9. jimmyp11

    jimmyp11 Rookie

    Dec 25, 2019
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    jim patterson
    I also timed it, from a cold start its about 40 sec at 2K, then drops to 1K. So I guess long and short this sounds correct. I just was wondering if it needed to run @ 2K for 40 seconds? Sounds like it does . . . .
     
  10. thorn

    thorn F1 Rookie
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    #8 thorn, Nov 28, 2020
    Last edited: Nov 28, 2020
    Honestly, I'd leave well enough alone, Jim (I'm also in Florida). My QV starts around 1700-1800, drops to 1100 (no load) and 1000 (with load). If it's not causing issues (and inherently, it won't), let it be.
     
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  11. jimmyp11

    jimmyp11 Rookie

    Dec 25, 2019
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    jim patterson
    I need to find some Ferrari guys down here - I'm in Port Charlotte. I agree, its not a big deal I was just wondering if there was a way to make it not do idle high for a min. But its really not an issue. Only reason I even thought of it was I ran across that article by birdman on the older 308s'

    jim
     
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