Disabling cold start fast idle on 84 QV | FerrariChat
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Disabling cold start fast idle on 84 QV

Discussion in '308/328' started by Rossa a nord di, Mar 23, 2014.

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  1. Rossa a nord di

    Rossa a nord di Karting

    Apr 30, 2008
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    Brent Pilon
    #1 Rossa a nord di, Mar 23, 2014
    Hi guys
    I have an US 84 QV that revs at 2000rpm for 15 mins and longer when it's really cold outside before returning to 1000rpm.

    I have read quite a bit on disabling the 2 valve cars cold fast idle and some 83s as was described by birdman and others.
    The problem is the 84 and 85 apparently do not have a cold start valve and only use the auxiliary air valve so I have not found any information on disabling them.
    So I have 2 questions.
    1: Do most people still recommend disabling the fast idle like in the other years, or do people recommend replacing the AAV and keeping the system in place?
    2: If the first answer is to disable, then is it as easy as plugging the hoses to the AAV to disable the cold fast idle on my 84 Thanks.
    p.s. I have cats but not plugged in…if that makes a difference.
    Also contemplating getting Dave Helms gold connector kit for the engine management which I imagine addresses some of these issues.
    Thanks. Brent.
     
  2. bentrm

    bentrm Formula Junior

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    #2 bentrm, Mar 23, 2014
    I have an 83. Not sure if 84's are the same but I simply bypassed the sensor on the coolant expansion tank. Just jumped the wires. It works. I'm interested if anyone has done the same or if anyone thinks this is a bad idea.
     
  3. ClydeM

    ClydeM F1 World Champ
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    #3 ClydeM, Mar 23, 2014
    I just did the same thing. The sensor is NLA and even getting a used one is tough.
    A visit to radio shack or Pep boys & you can buy a "piggyback twins" spade connector.
    Down side is I don't have a warm-up idle until I get a replacement sensor.
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #4 Steve Magnusson, Mar 23, 2014
    This (the long time for the AAV to close, but eventually OK warm idle) can indicate that the AAV's internal electric heater isn't working. Two thing to check:

    1. unplug the AAV electrical connector when the engine is running and measure the voltage between the two pins in the harness side connector = should always be +12V whenever the engine is running.

    2. measure the resistance between the two electrical terminals on the (unplugged) AAV -- should be a relatively low value (a few hundred ohms IIRC); a value of infinite ohms = bad (open) resistive heating element in the AAV.
     
  5. Rossa a nord di

    Rossa a nord di Karting

    Apr 30, 2008
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    Brent Pilon
    #5 Rossa a nord di, Mar 23, 2014
    Thanks guys.
    I have seen some previous posts on the problem and unfortunately it does seem that it is different than the 83. i'm not sure if jumping the wires would solve it. Birdman mentions this in his write up but only up to 83.

    Steve I will definitely try that. Thanks. What are your thoughts on disabling it like other 308s? Should I not just get rid of it all together and save the engine some high revs when it's cold? Love to hear your thoughts.
    Brent
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #6 Steve Magnusson, Mar 23, 2014
    Last edited: Mar 23, 2014
    I believe that you are mixing up issues here a little bit. The AAV is a basic component of all Bosch CIS systems (regardless of version/type) -- this is not commonly disabled (and there is only goodness to keep it operational, and only downside if you removed/disabled it). The 1980-1983 US version F (K-Jet without Lambda, but with cats and continuous belt-driven airpump air injection) additionally have the cold start air valve system (your '84 US doesn't have this) -- this system often gets removed (not my preference), or modified (my preference), to lower the cold light-off engine RPM.

    AAV(s) need to be present and operational. It could still have some sort of internal thermo-mechanical/mechanical problem causing the closing action to be lazy/slow, if the electrical heater stuff is OK, but don't go there until confirming/denying those simple electrical items (even just unplugging it, and replugging it in, could fix a bad/corroded connection.)
     
  7. Rossa a nord di

    Rossa a nord di Karting

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    #7 Rossa a nord di, Mar 23, 2014
    Thanks. I think I understand now. I thought the only use was that it was open when cold and closed when warm. I thought that if I closed it, it would simulate warm situations and avoid high RPMs when cold.
    I will perform the tests you recommended. I have found some for around $300. Not bad price I guess if it turns out to be bad. Thanks a million. Brent.
     
  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #8 Steve Magnusson, Mar 23, 2014
    Yes, but the idle RPM would be too low when cold (as the engine and gearbox oils are more viscous when cold). Your main problem isn't the cold light-off RPM being 2000 RPM, it's being at a raised RPM for 20 minutes (that probably increases a little over the first few minutes) rather than being increased for just a couple~few minutes (and always decreasing from cold light-off).
     
  9. Rossa a nord di

    Rossa a nord di Karting

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    #9 Rossa a nord di, Mar 23, 2014
    Yes your exactly right. I could handle 2-3 minutes then return to normal idle. I will perform the tests in the next few days. I'll let you know what I find out.
    Thanks again.
     
  10. Rossa a nord di

    Rossa a nord di Karting

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    #10 Rossa a nord di, Mar 24, 2014
    Last edited by a moderator: Sep 7, 2017
    Hi again.
    Ran the the tests that Steve recommended.

    I have 11.66 volts at the connector with the car running after jamming the probes in tightly.

    I also get a resistance of about 200ohms on the connector at AAV.
    It is definitely not infinite resistance.

    Is the next step to remove the AAV and inspect in warm and cold temps?

    Also found an electrovalve under the coolant expansion tank. Going to do a little research then I'll probaby post some pics. I know it's not part of a cold start system as the QVs do not have it but I'm curious to find out what it does! It looks like the cold start system from
    The older cars as it has vacum lines that go to another valve and also to the intake!
    Image Unavailable, Please Login
     
  11. Rossa a nord di

    Rossa a nord di Karting

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    #11 Rossa a nord di, Mar 24, 2014
    Last edited by a moderator: Sep 7, 2017
    The first pic is the electrovalve and the second is the valve that receives the vacum line.
    Had something similar on my 1990 TR but can't quite remember how it worked.
    Image Unavailable, Please Login
     
  12. Rossa a nord di

    Rossa a nord di Karting

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    #12 Rossa a nord di, Mar 24, 2014
    The first pic is #36 (111704) on table nine of the spare parts catalogue and the second pic is #26 (119694). Any info on what their function is would be appreciated.
    Thanks. Brent
     
  13. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #13 Steve Magnusson, Mar 24, 2014
    Why can it never be the easy things :(

    Those other components are part of the pulse air injection system (which has no relationship to how much air enters the intake system).

    Generally, yes, but you might try just "pinching" one of the large air hoses closed during the high cold idle operation (to simulate a fully closed AAV) to confirm that that is the path allowing the extra air into the engine -- i.e., pinch one of the air hoses closed and the cold idle drops significantly = further test (watch) the AAV internal blocking plate motion with the AAV off the car and going from cold to warm; if the cold idle stays high with one of the AAV's large air hoses pinched closed = it's not an AAV problem.

    Have you downloaded, and read, Chapter D of the Mondial 8/QV WSM?
     
  14. Rossa a nord di

    Rossa a nord di Karting

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    #14 Rossa a nord di, Mar 24, 2014
    Thanks Steve. Never the easy things!

    I will try pinching the lines. They seem rock hard and I'm scared to crack them but I'll start slow. If that fails I might run it for 10 minutes until it's warm, then remove it and plug the line for a minute to see if the idle falls.

    I have been reading some of your previous posts on the electrovalve and diverter valve so I have a better understanding now.

    I do not have Chapter D. My manual has no chapter D. I thought it was strange. I have the 308QV/328 workshop manual.
    I'll have to look that up. Could be useful….
    Thanks again for your help. I'll let you know how pinching the line goes or visual inspection of the AAV off the car goes.
     
  15. Rossa a nord di

    Rossa a nord di Karting

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    #15 Rossa a nord di, Mar 24, 2014
    Just downloaded. Great info!!! Thanks for letting me know about that. I should have a better understanding now.
    Take Care. Brent
     
  16. Crowndog

    Crowndog F1 Veteran

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    #16 Crowndog, Mar 24, 2014
    If your test reveal a functional AAV perhaps you might want to check the mechanical parts like cable, throttle linkage and even the throttle pedal. Any could be sticking and finally loosening after 20 minutes of vibration. Then vacuum leaks, I had a broken nipple on the charcoal canister and had high idle. It's a long shot but ..........


    Sent from my iPhone using Tapatalk
     
  17. Rossa a nord di

    Rossa a nord di Karting

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    #17 Rossa a nord di, Mar 25, 2014
    Thanks. Checking for vacuum leaks is the next step, then looking at the CIS in general; the TPS, etc…
    I will still double check the AAV because I have my coolant expansing take loose it should be relatively easy to check.
    Brent
     
  18. Crowndog

    Crowndog F1 Veteran

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    #18 Crowndog, Mar 25, 2014
    Note: in the TPS the s stands for switch. With engine off you should hear it click while moving from throttle off to wot.
     
  19. Rossa a nord di

    Rossa a nord di Karting

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    #19 Rossa a nord di, Mar 25, 2014
    I removed the AAV from the car.
    Hoses were loose and just pulled off easily; clamps were not tight; might have been part of the problem.

    The inside shows an open hole at room temperature. Placed in the oven at temps rising from 170'F to 210'F and the hole never completely closes. After 15 minutes it is 80-90% closed. I suspect that this is my problem.

    If I understand it correctly, the AAV will warm up from the electrical component but also ambient temperature.

    I am assuming that this means I have a faulty AAV and I will be sourcing one out. I hope this is the problem. I have been backwards on my understanding before but I am pretty sure that the plate should be completely occluding the hole when warm and 15mins in the oven at 200' is more than enough time.
    If i'm wrong let me know before I order it.
    Thanks Crowndog. I do have a Bosch fuel injection book and I previously set the microswitch as you mentioned. I thought it may have moved but I'm going to chase down the AAV for now.
    Thanks. Brent.
     
  20. Rossa a nord di

    Rossa a nord di Karting

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    #20 Rossa a nord di, Mar 25, 2014
    Apparently the AAV for the QV is NLA. Anyone have an idea where to get one? Price isn't a big deal for my. I don't mind paying to get the right part.
    Thanks.
     
  21. Crowndog

    Crowndog F1 Veteran

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    #21 Crowndog, Mar 25, 2014
    I no longer need mine since conversion. Have not tested it but assume it was working when taken off.


    Sent from my iPhone using Tapatalk
     
  22. Rossa a nord di

    Rossa a nord di Karting

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    #22 Rossa a nord di, Mar 25, 2014
    Found one on ebay from an 87 328. Exact same Bosch part #;
    I spent all day trying to find a suitable one from info from previous posts but not successful.
    This one was $100 so I thought it would be a good gamble. They had not tested it but for $100 I'll see what happens.
    Also spoke to Charles at Italian Car parts who rebuilds them.
    You have to send in your core, but he indicates that there is a 40% chance that your core will not be rebuildable and you re still out of luck.
    So if this one doesn't' pass the tests, I might send both cores in for only a 20% chance of failure. I like those odds!
    I'll let you know how it turns out.
    Thanks. Brent.
     
  23. jimpo1

    jimpo1 Two Time F1 World Champ
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    #23 jimpo1, Mar 25, 2014
    Search this site. It's a Porsche part too, and they're readily available.

    EDIT: Here you go, I paid $27 for mine, used.

    http://www.ferrarichat.com/forum/308-328/343829-328-auxillary-air-valve.html
     
  24. andyww

    andyww F1 Rookie

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    #24 andyww, Mar 25, 2014
    You would also need to check the internal heater by applying 12 volts to the connector. It should cause the valve to completely close in 2-3 minutes.
     
  25. Rossa a nord di

    Rossa a nord di Karting

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    #25 Rossa a nord di, Mar 25, 2014
    Thanks guys
    Crowndog, sorry I missed your post. I would have taken you up on it.

    I read the thread about a Wells-AC4233 but was unable to find it on line anywhere.

    If this one is a bust I might come knocking for more advice. I checked the mentioned parts dealers but none popped up. At least I feel a little better knowing that I have options.
    Thanks. Brent.
     
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