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Eliminate the High Idle on 85 QV?

Discussion in 'Technical Q&A' started by 308GTS, Dec 25, 2003.

  1. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,220
    TN
    Well I thought I would start a thread on this. Many of us would like to eliminate the high idle on our later model QVs. Just to give some info. My 83's high idle can be stopped via the coolant temp sensor but this does not work on my 85' QV. Now my 85' QV isn't stock so your mileage may vary. Many have stated to install a bearing in the AAV. I don't see one on my 85' that doesn't mean that they don't have one but I just haven't seen it yet. My 83' does have one. So what is the best way to stop the high idle on an 85'. The items I see are the FD and metering device with damper, WUR, Cold start injector, pump, accumulator, filter. and coolant temp sensor, TPS. I don't see an AAV or other CIS components that my 83' does have. Thanks.
     
  2. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,157
    Texas
    Full Name:
    Steve Magnusson
    One problem with completely eliminating the extra air allowed into the system by the Auxillary Air Valve (if that's the only modification) is that the cold AF mixture will be very, very rich because the fuel side will still be adding the extra fuel that it "thinks" it needs to add (and it really adds a double shot of fuel: 1) for general cold enrichment and 2) even more to enrichen the extra air coming thru the AAV to the same level).

    However, I think "tuning" the amount of air that the AAV allows in is a perfectly reasonable thing. IMO 3K cold RPM is excessive/unnecessary, but the 2K cold RPM you mentioned on the other board doesn't seem that bad -- are there no typical cold RPM values/targets given in the OM or the WSM? AAVs are rather crude open-loop thermo-electro-mechanical gizmos, and there might actually be a (paint-locked) adjustment you could fiddle with (or perhaps tweaking the internal linkages) if you don't want to add another valve/restriction to the AAV air line (but I wouldn't intentionally try to go below 1500 RPM cold).

    On your '85QV the AAV is item 30 in the SPC illustration -- is yours missing and the ports/lines plugged?:
     
  3. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,220
    TN
    Thanks Steve. Great info. Now why does jumpering the coolant temp sensor stop the high idle on my 83' but won't on the 85'? I will check and see if the AAV is there. I did notice that a few of my CIS components are missing and vacuum caps are now there. I assume it must be there as this raises the idle but I will look. If it is there are there any other alternatives beside a bearing or ?. Thanks Again and Merry Christmas to all!!!!!
     
  4. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,157
    Texas
    Full Name:
    Steve Magnusson
    On your '83QV there are two things that add extra air when cold: the AAV and the Cold Start Air Valve (see page 68 in the 260/83 OM) -- when you jumper the coolant temp sensor you disable the Cold Start Air Valve. Your '85QV only has an AAV to add extra air when cold (see OM 307/84).

    IMO you don't want a solid ball bearing in one of the AAV lines (which will block the AAV airflow completely) -- you need a "bearing" (or how about a short wooden or plastic dowel) with a drilled hole down the center to form an orifice that you can progressively enlarge until the max cold RPM is 1.5K~2K-ish (or whatever is desired).
     
  5. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,220
    TN
    Thanks Steve. I completely understand now. I appreciate the info. Merry Christmas!!!!
     
  6. mr. green

    mr. green Formula Junior
    BANNED

    Oct 31, 2003
    263
    CAN YOU HEAR ME
     
  7. Doc

    Doc Formula Junior

    Sep 13, 2001
    886
    Latham, New York
    Full Name:
    Bill Van Dyne
    Would it be possible to include a picture of the Aux air valve on an '85 and where to install a peg/bearing? Thanks.
     
  8. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,157
    Texas
    Full Name:
    Steve Magnusson
    Doc -- I don't understand your request as the picture below shows the AAV on 84/85 US 308QV. The partial blockage would be installed in either line 35 or line 36 (to limit the max cold RPM).
     
  9. Doc

    Doc Formula Junior

    Sep 13, 2001
    886
    Latham, New York
    Full Name:
    Bill Van Dyne
    OOps--sorry. I missed the nice illustration because, since the new Chat software has been implimented, my computer won't show pictures. I was just able to download this one through some juggling with I-E.

    OK--now I know where it is--thanks very much.
     

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