308 warm idle issue, WUR at fault? | FerrariChat
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308 warm idle issue, WUR at fault?

Discussion in '308/328' started by Dmctwelve, Sep 10, 2011.

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  1. Dmctwelve

    Dmctwelve Karting

    Jun 25, 2011
    55
    Mass
    #1 Dmctwelve, Sep 10, 2011
    I have done some searching but not having much luck. On my 1980 GTS it will start fine when cold and idle around 1k, after it warms up (not even full operating temp) the idle will stay around 1500-2k rpms. the cold start valve has been removed and lines plugged. also both electro valves have been unplugged and vac lines capped. The car runs great and always starts easily no matter if its hot or cold. when the A/C is on it will drag the idle down a little bit but i think that is normal regardless of what rpm it is idling at. the car was doing the exact same thing when the valve was still in place. removing it and plugging off the lines made no difference. all lines appear to be tight and i dont think they are leaking.

    anybody have any insight on where to look next? could the WUR be at fault?

    thanks in advance!
     
  2. fastradio

    fastradio F1 Rookie
    BANNED Professional Ferrari Technician

    Apr 26, 2006
    3,664
    New England
    Full Name:
    David Feinberg
    #2 fastradio, Sep 10, 2011
    These are somewhat odd symptoms, with the idle rising as the vehicle warms up. By cold start valve, do you mean the cold start injector, or are you referring to the aux. air valve?

    CIS warm and cold pressure are always nice to know when starting the diagnostic process, although nothing that you've said thus far points directly to the WUR. Also, do you know if the throttle plate "base" angle has been tampered with? Have you tested for mixture level and/or for vacuum leaks?

    We deal frequently with these types of problems and often find that there are several causes to the concern that you describe.
     
  3. Dmctwelve

    Dmctwelve Karting

    Jun 25, 2011
    55
    Mass
    #3 Dmctwelve, Sep 10, 2011
    The valve that i removed was the aux air valve, not the actual cold start injector. The system did not work prior to removing it and both electro valves were unplugged, plugging them in caused the idle to jump way up so it was always left unplugged. The other day i removed the valve and made sure the van lines were capped off properly. i did fond some loose hoses but none of it made any difference in the idle speed once warm.

    I do not have any pressure readings as of yet, I have no idea if the throttle plate base angle has been tampered with? if I had to guess I would say that it has been lol. What is the easiest way to test for mixture level? and vac leaks? everything seems to be tight with the exception of one hose on the pass side of the plenum that runs over into the wheelwell it looks like, that hose is loose on the barb.

    I wiped out the TB, and it was a little dirty, but did not look like it was anywhere near enough to cause it to stick. the return spring feels strong as well.

    I plan to take it for a ride again tomorrow and see if i can narrow it down any further. any other thoughts? thx
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,854
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #4 Steve Magnusson, Sep 10, 2011
    Last edited: Sep 10, 2011
    I think the nouns are getting a little mixed up and might be confusing things a bit:

    cold start air valve = this item is only used on a US 308i-2V and gives the crazy super-high cold idle RPM (my guess is this is what Dmctwelve removed/disabled).

    cold start injector (or sometimes cold start valve) = a fuel item, not an air item.

    aux air valve = used on both euro and US (you wouldn't normally remove this).

    Sounds like your system has been well-molested Dmctwelve so you never know how many other things have been (wrongly) tweaked, as fastradio mentioned, so I wouldn't be hopeful that you'll have a simple, single fix.

    Newman posted a interesting new "air leak" possibility in post #4 of this thread for your model:

    http://www.ferrarichat.com/forum/showthread.php?t=336369&page=2
     
  5. Paul_308

    Paul_308 Formula 3

    Mar 12, 2004
    2,345
    #5 Paul_308, Sep 10, 2011
    Last edited: Sep 10, 2011
    The Warm-Up Regulator has no effect on idle speed, it simply controls fuel pressure to compensate for cold start, normal run, and wide-open throttle conditions.

    The AAV or Auxillary Air Valve controls idle speed by bypassing air flow around the throttle plate. When the engine is cold, the channel through the blocking plate is open. As soon as the engine is started, voltage is applied to heat a bi-metal strip to allow the blocking plate to gradually close the channel, reducing idle rpm from 1200 to 1000. When tubing is misconnected by evil part removers, who knows.

    Soooo, your AAV needs inspection to the tubing and perhaps an internal clean-up. They have been known to dirt-up and not work freely. The connector to the bi-metal heater may have gotten removed. But more likely, since your idle is bassackwards, the vacuum tubing has probably been mis-connected to a 'slow idle' in the part removal attempt to improve on what Ferrari determined what worked best.

    ASIDE: Do people actually think a car goes faster if you remove parts?

    Your Owner's Manual (188-80) has a complete section on this stuff including the idle speed setting, diagrams of the components. The Pollution Label and TuneUp label (unless they were removed too) also has diagrams and help info. There are also many internet articles on the Bosch K injection as it was widely used by Porsche, VW and MB in the early 80s. Google 'Bosch Jetronic'.
     

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