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Car Stalls When Coming To A Stop

Discussion in 'Mondial' started by ssrealty, Jun 15, 2011.

  1. ssrealty

    ssrealty Formula Junior

    Sep 12, 2010
    325
    Austin, TX
    Full Name:
    Chris Warren
    My Mondial 85 QV frequently stalls when coming to a stop (drives fine for 2-3 days and then stalls suddenly). You can increase throttle to increase RPM and prevent car from stalling. If you watch RPMs after taking foot off gas, you will see the RPM needle drop and the ignition light will turn on/blink if you don't increase throttle immediately. After stall, car will start up immediately. And sometimes, it will immediately idle again with no problems. I don't think it is a fuel problem, because you can increase throttle to prevent stall. Very strange. Any suggestions?
     
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  3. PV Dirk

    PV Dirk F1 Veteran

    Jul 26, 2009
    5,401
    Ahwatukee, AZ
    I just read the bosch fuel injection book and I know enough to know that this simply makes me dangerous. Let's consult the book.... and that's only if it's fuel.

    The only one close listed is "engine starts but stalls at idle" I know this isn't your problem because it does run fine and it is mostly when slowing down. Is it associated will fully warmed up, cool, in between?

    Number one thing to check for above issue is fuel pressure. Cold start valve leaking, aux-air regulator/idle speed stabilizer faulty (I like this one), vaccuum leak, intake air. The rest are more serious issues that are unlikely. I like the vaccuum leak or the idle speed stabilizer.

    The best advise I have is to not take advise from someone who just read a book about something. Good luck.
     
  4. hank sound

    hank sound F1 Veteran

    Jan 31, 2004
    5,786
    Burbank, CA
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    Hank Garfield
  5. Valenzo

    Valenzo F1 Veteran

    Dec 4, 2010
    5,013
    IL & NC
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    Ted
    +1. The guy is a wealth of methodical practical information. We spoke one evening for over an hour and the way he explains Mondial ailments and cures you feel you are talking about fixing a lawn mower, he's that practical. I bought his GCK afterwards without a second thought
     
  6. PAP 348

    PAP 348 Moderator
    Moderator Owner

    Dec 10, 2005
    86,854
    Mount Isa, Australia
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    Pap
    Sounds like the one or the other to me. :):)
     
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  8. ssrealty

    ssrealty Formula Junior

    Sep 12, 2010
    325
    Austin, TX
    Full Name:
    Chris Warren
    Well, I finally took my 85 Mondial to shop. The car consistently stalled when coming to a stop. RPMs would drop, and engine would stall if you did not give throttle while braking.

    David Moore with Moorespeed in Austin quickly diagonosed the problem. The warm up regulator (WUR) needed to be replaced. This controls the fuel pressure in the CIS sytem.
    Ferrari wanted $3,000 for the part. Fortunately, David was able to find a rebuilt unit for $700. It was the last one his source had. Bosch will no longer be manufacturing these parts, and the costs have really gone up. Amazing how expensive a simple part is.

    Moorespeed also replaced the air injection valve at header. The engine bank by back seat sounded like it had an exhaust leak. Car was in shop only two days. Car runs much better, and I am happy I did not have to pay $3,000 for a warm up regulator.

    Just thought I would share this with anyone who has an idle or stallling problem.
     
  9. Wade

    Wade Three Time F1 World Champ
    Rossa Subscribed Owner

    Mar 31, 2006
    32,194
    East Central, FL
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    Wade O.
    #7 Wade, Jul 22, 2011
    Last edited: Jul 22, 2011
  10. PV Dirk

    PV Dirk F1 Veteran

    Jul 26, 2009
    5,401
    Ahwatukee, AZ
    Thanks for the update. The book was partially correct with the fuel pressure diagnosis, unfortunately as you illustrate there are more than one elements of the system that manipulate fuel pressure. Glad you got it fixed.
     
  11. davidgovett

    davidgovett Karting

    Apr 9, 2010
    134
    Nice to see a post from a fellow Austin area Mondial owner! Can't beat Moorespeed for getting things done. So far, they have been the best resource for better priced parts compared to anything I can find online.

    Cheers
    Dave (Georgetown TX/1988 Mondial 3.2 coupe/Red/Tan)
     
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  13. ssrealty

    ssrealty Formula Junior

    Sep 12, 2010
    325
    Austin, TX
    Full Name:
    Chris Warren
    Just thought I would give an additional update on the stalling problem. Moorespeed replaced the WUR a few weeks ago. This improved the stalling problem substantially. However, the car would still stall when coming to a stop intermittently.

    I took it back to Moorespeed. Upon further inspection, the purge valve located underneath the air intake box had come loose. This caused a periodic vacuum leak which caused the lambda unit to richen the mixture and cause stalls. We also replaced the oxygen (O2) sensor which was fouled. Ferrari wanted $375 for the oxygen sensor. Moorespeed was able to find a replacement sensor for $129.

    Now car is stall free. For the first time since I purchased car in February, I can drive with a/c turned on. Temperatures in Austin area have exceeded 100 degrees most of the summer, and we have a record drought. The a/c helps, but it is still darn hot driving with top down.
     
  14. PAP 348

    PAP 348 Moderator
    Moderator Owner

    Dec 10, 2005
    86,854
    Mount Isa, Australia
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    Pap
    I knew 'we' were on the right track, thanks for letting us know and glad to hear it's sorted now. :):)
     
  15. RichardAguinsky

    RichardAguinsky Formula Junior

    Nov 12, 2007
    477
    Palo Alto, Californi
    Full Name:
    Richard Aguinsky
    Reviving an old thread. I am running into this problem occasionally, only on very hot days.

    Where is the purge valve located? Do I need to take the air plenum out?

    Thanks,

    Richard
    1984 Mondial Cab, US model.
     
  16. mike32

    mike32 F1 Rookie

    May 13, 2016
    3,381
    Uk
    This stalling can also come from the injectors, it happened on mine coming to a stop sign, no fun when no brake servo- cure was a good shot of redex fuel treatment in the tank once a year and no problem over next 15 years
     
  17. Meister

    Meister F1 Veteran
    Silver Subscribed

    Apr 27, 2001
    5,448
    Duluth, MN
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    The Meister
    I had a,similar problem on my 85 euro QV cab. There is a little adjustment screw on the throttle stop/linkage. I adjusted the screw to slightly increase idle. The car still dips below normal idle when coming to a stop but recovers and does not stall. Cost was $0
     
  18. RichardAguinsky

    RichardAguinsky Formula Junior

    Nov 12, 2007
    477
    Palo Alto, Californi
    Full Name:
    Richard Aguinsky
    Thanks for the replies. I use fuel injector cleaner once per year and tried the idle screw when it was stalling. I just put in another bottle of Techron in the tank; see how it goes.

    So far it happened only once on a very hot day. Same as the OP.
     
  19. mike32

    mike32 F1 Rookie

    May 13, 2016
    3,381
    Uk
    How old are the injectors ?
     
  20. davemqv

    davemqv F1 Rookie

    Aug 28, 2014
    3,055
    USA
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    Dave
    Chris if you were able to buy a rebuilt unit, have you considered having your original WUR rebuilt to either sell on to someone who needs it or keep as a spare?
     
  21. RichardAguinsky

    RichardAguinsky Formula Junior

    Nov 12, 2007
    477
    Palo Alto, Californi
    Full Name:
    Richard Aguinsky
    The injectors are about 1000 miles old. Replaced them during the major service.
     
  22. mike32

    mike32 F1 Rookie

    May 13, 2016
    3,381
    Uk
    Have you had the cam belts done recently ?
    Might be an idea to check the compression readings
     
  23. wildcat326

    wildcat326 Formula 3

    Dec 10, 2012
    1,614
    Chicago, IL
    Full Name:
    Justin
    I have a 308 with carbs, so can't speak to WUR or injectors as a possible culprit, but what's the health of your alternator? Mine was on its way out when I got my car, and I had similar symptoms when not actively using the accelerator.
     

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