News

Funny Idle When Cold/85 QV

Discussion in 'Technical Q&A' started by abarthracer, Apr 28, 2004.

  1. abarthracer

    abarthracer Formula Junior

    Dec 6, 2003
    373
    Falmouth, Cape Cod
    Full Name:
    david S.
    Hello All,
    Can someone help me figure out what is going on with my car when cold? Here are the symptoms after not running for at least 24hrs or more.
    Starts right up, goes to about 12-1500RPM for 5-10 seconds then chugs down to 800ish. Try to give it throttle and it coughs and spits.
    If I disconnect one wire of the coolant temp switch at bottom of resevoir, going to open loop I think. When I reconnect the wire I hear a click of the selonoid on the left side of engine bay that has 3 vacuum hoses going to it. If I leave the wire disconnected while cold, the engine runs much smoother and you can give it gas. If I drive it after a few minutes of warming up, all of a sudden it feels as though someone turned a switch on and it runs great. I am assuming that is the coolant switch contacts opening and having an effect on that selonoid. What is the deal with that selonoid? I can't find any info on that. It takes quite a while for the car to warm up and is almost unsafe to drive due to lack of power when cold. THanks
    David
     
  2. To remove this ad click here.

  3. kdross

    kdross Formula Junior
    Silver Subscribed

    Feb 10, 2002
    872
    NJ
    Full Name:
    Ken
    I had the same exact problem with my 1985 308QV. You need to replace the switch (cost about $30). The switch works in conjunction with the Aux Air Valve for the fast idle system. If the switch if bad, you will experienc your current problem. I spent months resolving this problem. Search the archives for more info since I posted a lot regarding the problem. Search for AAV, Cold idle, and fast idle for more info. I also posted on the other Ferrari site (www.*****************) and received a lot of help.

    Ken
     
  4. abarthracer

    abarthracer Formula Junior

    Dec 6, 2003
    373
    Falmouth, Cape Cod
    Full Name:
    david S.
     
  5. abarthracer

    abarthracer Formula Junior

    Dec 6, 2003
    373
    Falmouth, Cape Cod
    Full Name:
    david S.
    Ken, thanks for the tips. My switch/sensor does work, I think it is something else down the line. By the way, what is the "other" site. Not famaliar with it. Thanks
    David
     
  6. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
    Full Name:
    Malcolm W
    Has the problem just appeared or has it been getting progressively worse, here are some areas to look into for what you have described.

    Check the vacuum system for leaks
    Check to see if the auxillary air device is fully opening
    The cold start valve could be leaking
    Check the "cold" control pressure - you would need access to some special equipment for this, but for example if the ambient temperature is 20°C the normal control pressure should be 0.65bar - 1.05bar.


    MW
     
  7. To remove this ad click here.

  8. M.James

    M.James F1 Rookie

    Jun 6, 2003
    2,720
    Worcester, MA
    Full Name:
    Michael.C.James
    I think I'm experiencing the same problem, but for right now its very mild - on most startups, the car can be coaxed into 2000 rpm warmup idle. Lately, its needed more and more help getting to that 2000 rpm idle for warmup - the rpms keep dropping before the car is warmed up.....annoying for now, but I want to make sure things are good and ready before I start blasting down the highway.

    Since I'm no mechanic (working on it with THIS car....) I'd like to ask some bone-head questions before I consult my shop manuals:

    The Vaccuum system relates to the coolant system?
    The Cold Start valve and the Aux Air Valve are the same?

    Just thought I'd get some of the terminology straight before I go researching where these systems are in the engine bay....
     
  9. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
    Full Name:
    Malcolm W
    Michael,

    The vacuum system does not refer to the cooling system, various components on the fuel injection system are influenced by the engines vacuum.

    The cold start valve or sometimes refered to as the cold start injector, aids cold starting of the engine by spraying fuel into the engine when the engine temperature is cold and when the starter motor is activated - this is controled by the thermo time switch.

    The auxillary air valve also aids the engine when cold, by opening a small port in order to increase the engine's idle speed. The valve is controled by the heating of a bi-metalic strip or by natural heat soak from the engine.


    MW
     
  10. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,220
    TN
    Sticking AAVs are common especially being a 20 year old part.

    AAV and CSI are 2 diff. components.

    AAV is under the coolant recovery tank in 84-85 308 QVs.

    CSI is on the right side of the plenum chamber(big red thing that says Ferrari Quattrovalvole on it) with a blue harness connector on it.
     
  11. abarthracer

    abarthracer Formula Junior

    Dec 6, 2003
    373
    Falmouth, Cape Cod
    Full Name:
    david S.
    Mark,
    Thanks for the tips. So far these are the results of having the car for only 3 weeks.
    *cold start valve: working and not leaking
    *AAV was working, took it off, put 12v to it and it opened, put in fridge, and it closed
    *Have checked the vacuum and it seemed low to me at around 10 inches. I posted a query about what is normal vac. and a couple of replys came back that it was fine. I am used to seeing 15-20 on many other engines.
    *cold control pressure: I just picked up a CIS pressure kit and will check it soon. Going on vacation/holiday for a week and probably won't check till after that.
    * I still havn't figured out what the selonoid is with the vacuum lines on it that the temp sender on the bottom of the resevoir seems to control. It is on the drivers side right underneath the fuel filler in the engine comp. Check my original post again for the symptoms.
    At this point I think it is the WUR or a vacuum issue since it runs much better with the one wire disconnected from the temp sender. Which by the way is working with continuity when warm/cold and the opposite when cold/warm. Can't remember which way it is supposed to go!
    But have not seen the immediate RPM's go to 2K at start up. Still searching.
    Thanks
    David
     
  12. To remove this ad click here.

  13. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,073
    USA
    Full Name:
    Hugh G. Rection
    For those that would like a little primer on the FI system, check here:
    http://www.auto-solve.com/mech_inj.htm

    It is missing the info on the lambda sensor (O2 sensor), and throttle position sensor, but probably not relevant to a cold start issue. Or is it? I'm not a mechanic....
     
  14. M.James

    M.James F1 Rookie

    Jun 6, 2003
    2,720
    Worcester, MA
    Full Name:
    Michael.C.James
    I looked into replacing the thermal cold-start switch that kdross describes - instead of $30, I found one from Ted Rutlands for $105........

    The AAV unit, replacement cost, runs around $300. The CSI unit looks to be well over $600......

    Anyone recommend a better source, at least for the switch?
     
  15. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,220
    TN
    Are you referring to the Thermo Time Switch or the Coolant temp sensor.
    The thermo time switch sits in between the plenum and screws into a coolant passage in the block. The Coolant temp sensor has 2 wires that connect to it and it is on the coolant recovery tank. If your Cold Start Injector isn't spraying when cold then it is probably your Thermo Time Switch. They are around $60 or so new. A CSI shouldn't be much. $70 or so I would think. You can check it though so you don't replace it when it is working fine.
     
  16. Doc

    Doc Formula Junior

    Sep 13, 2001
    886
    Latham, New York
    Full Name:
    Bill Van Dyne
    Ken--where did you get your thermal time switch for $30? My '85 does the same thing at cold start in warm weather only. When the outside temp drops, the cold start system works perfectly. I thought that the system might just be very sensitive to outside temperature--when it's warm outsde it seems that the car doesn't need to use it.. I haven't seen this as a problem in that the car idles fine and needs to warm up a bit--something which should always be done anyway.
     
  17. kdross

    kdross Formula Junior
    Silver Subscribed

    Feb 10, 2002
    872
    NJ
    Full Name:
    Ken

Share This Page