Disabling the additional cold-start system, 1985 308 QV | FerrariChat
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Disabling the additional cold-start system, 1985 308 QV

Discussion in '308/328' started by jim rosenthal, Feb 8, 2023.

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  1. jim rosenthal

    jim rosenthal Karting

    Sep 10, 2006
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    #1 jim rosenthal, Feb 8, 2023
    My 1985 308 QV, when started from cold, revs up to 2500 rpm immediately. I can't imagine this is good for a cold engine, although the oil pressure does come up right away as well. But it certainly isn't what I would prefer.

    I reviewed the article on Birdman's 308 site regarding this, and printed it out and brought it to the car. The article seems specific to 1981-1983 308s, NOT to the 84 and 85 cars. So: do the 1984 and 1985 cars have a similar system which functions as an additional cold start system to speed up the cold engine, and warm up the catalyst? And, if so, how do I disconnect it or stop it from working?

    Ironically, my car no longer has catalyst(s). They were removed by a prior owner who fitted an ANSA exhaust system which is actually a set of headers. They fit well and sound fine, and I have no plan to remove them, although it's unlikely they do much other than make the car sound better.

    Any suggestions on the cold-start topic are welcome. I did search on this topic, but did not find anything specific to it, which may speak more to my search savvy than to what's out there on Fchat. Thank you all in advance!
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #2 Steve Magnusson, Feb 8, 2023
    Last edited: Feb 8, 2023
    No, they don't. On an '84-'85 308QV, the only device intentionally adding extra air at cold start-up is the AAV. Can't say that we've had many (if any) reports of an AAV opening too much at cold start-up, but it is possible. Where are you located and what is the ambient temperature when you get the 2500 RPM at cold start-up?

    It also possible that you may have the wrong AAV installed -- so you might check the 10-digit Bosch PN on it. My notes have:
    '82-'86 euro version 308QV (K-Jet without Lambda): AAV = Bosch 0280140104
    '84-'85 US version 308 QV (K-Jet with Lambda): AAV = Bosch 0280140229
     
  3. jim rosenthal

    jim rosenthal Karting

    Sep 10, 2006
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    #3 jim rosenthal, Feb 8, 2023
    Steve, I am located in MD, near Baltimore. The temp last evening when we started the car and it revved up was about 40 degrees F. My car is supposed to have Lambda, I think, but I have not been able to locate a Lambda sensor anywhere in the exhaust system.

    I'll find the AAV and see if I can read the part number off it. Thank you for your help!!
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    Steve Magnusson
    #4 Steve Magnusson, Feb 8, 2023
    Well, the cold start RPM should be up some at 40 deg F.

    Is your fuel distributor silver (euro K-Jet without Lambda) or black (US K-Jet with Lambda)? Could it have been a euro version 308QV that at one time had a quasi-Lambda system added to be US legal, but those additions have now been removed?

    The location of the AAV is also a clue:
    US version = AAV mounted to bottom of the coolant expansion tank
    euro version 308QV = AAV mounted to top of engine near the front (sort of just behind the water pump)
     
  5. jim rosenthal

    jim rosenthal Karting

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    #5 jim rosenthal, Feb 8, 2023
    It's black, and I'm pretty certain it's at the bottom of the coolant tank. What I have NOT found is a Lambda sensor. Where would that be located?
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,875
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #6 Steve Magnusson, Feb 8, 2023
    Last edited: Feb 8, 2023
    In the exhaust stream/piping at the entrance to the catalytic converter. Item 25 here:

    https://www.ferrariparts.co.uk/diagram/ferrari/308-quattrovalvole-usa/015-exhaust-system

    It mounts into a threaded port on the entrance side of the catalytic converter 14. Even if your catalytic converter has been replaced by a test pipe, it should still have a threaded port to install the O2 (Lambda) sensor.
     
  7. daynyc

    daynyc Karting
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    #7 daynyc, Feb 8, 2023
    I believe my late 1984 US 308QV has the same set up as you do. I experimented with partially plugging the AAV hose with an appropriately sized piece of wood dowel with a small hole drilled in the center. I adjusted the cold start speed this way to 1800 RPM.


    Sent from my iPhone using FerrariChat
     
    moysiuan and Steve Magnusson like this.
  8. BrockBenson

    BrockBenson Formula Junior

    Oct 18, 2018
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    #8 BrockBenson, Feb 8, 2023
    For what it's worth, my Dec 84 QV also had an aftermarket exhaust. The lambda sensor was re-installed, but a bit difficult to see as it was sort of hidden above the primary pipe going into the aftermarket muffler.
     
  9. jim rosenthal

    jim rosenthal Karting

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    #9 jim rosenthal, Feb 8, 2023
    Steve, this is very useful and thank you. My car no longer has a catalytic converter, plus it has an ANSA exhaust system fitted by a prior owner. But it may still have the Lambda sensor. We'll look for it, and much obliged.

    @daynyc, that is a very clever idea and we may emulate it and see if we can reduce the cold idle speed. thank you also.
     
  10. daynyc

    daynyc Karting
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    #10 daynyc, Feb 9, 2023
    It may seem unsophisticated, but I like simple and reversible solutions. I think the dowel was around three-quarter inch OD. After some experimentation, I ended up with a rather small hole, I believe 3/16 of an inch. I just placed the drilled dowel in the rubber hose that runs from the aluminum manifold from the fuel injection distributor, which enters the hose into the throttlebody, to the AAV valve under the coolant tank.


    Sent from my iPhone using FerrariChat
     
  11. daynyc

    daynyc Karting
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    #11 daynyc, Feb 9, 2023
    I will add that I am quite sure I have the same set up as you and everything: injection, AAV etc. was functioning well. I also originally had a cold idle speed of about 2500 RPM which I also thought was too high. The dowel only has to be about an inch long and, of course, you can pick the speed you like by the size of the hole you drill in it. The AAV, when working correctly, is simply opening and closing that auxiliary air hose.


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