308 gt4 stalling with a/c on | FerrariChat
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308 gt4 stalling with a/c on

Discussion in 'Technical Q&A' started by rickjaffe, May 21, 2005.

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  1. rickjaffe

    rickjaffe Formula Junior

    Mar 6, 2005
    363
    houston
    Full Name:
    richard jaffe
    #1 rickjaffe, May 21, 2005
    when I have the a/c on the car sometimes stalls at stop lights, even after it is at normal operating temps. It's ok when the a/c is off; I've only started having this problem since the outside air temp is over 90. Is the idler set too low. I had a similiar problem with my vette; I guess I just bumped up the idler up alittle. But that car only has one carb. this one has 4. would it be any different? does each carb have it's own idler adjustment. I should say that I'm not too handy and synching four idlers in the carb is probably beyond what I could do from the posts I've read about synching carbs.
     
  2. dinogt4guy

    dinogt4guy F1 Rookie

    Oct 31, 2004
    3,411
    Hewitt, Tx.
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    Kurtis Fordice
    #2 dinogt4guy, May 21, 2005
    Rick

    I would agree about the idle set too low. Where does it Idle at w/o the air on. Mine idles around 950. Never have any issues like that. I wonder if the brg in the pump could be going bad Causing more drag than usual? Or maybe could the pump have too much pressure or something wierd like that. Thought I'd just throw a couple other questions out there. Probably not either one. According to my work shop manual tha idle should be 900-950. Do you know which are the idle adjustment screws? It says to adjust the 2 screws the same ammount to achieve the proper idle. They are on the drivers side carbs, the screws are on the right side about 1/2 way down right next to the body of the carb. NOT the ones on the linkage inbetween the carbs. If your not comfortable with trying this have the shop do it or someome you know and trust. Hopefully I'm not confusing you. I went out and looked at mine and its pretty easy to see. You will have to remove the air cleaner assy to easely see them I think. Mine has 4 k&N's on it so no problem to see them for me.

    Good luck

    Kurt

    There is nothing like a Ferrari, there never has been and never will be!
     
  3. robertgarven

    robertgarven F1 Veteran
    Owner

    Feb 24, 2002
    5,322
    Ventura, California
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    Robert Garven
    #3 robertgarven, May 21, 2005
    if I am not mistaken there is a single idle adjustment screw for all four. You Idle should be closer to 1000 rpm's mine was idling very low and I had a transfer gear noise. I disassembled the entire transfer gear assembly just to find out the idle was to low. A well known mechanic said the engine needed to be at spec as at lower idle the engine doesn't get into its groove so to speak.
     
  4. rickjaffe

    rickjaffe Formula Junior

    Mar 6, 2005
    363
    houston
    Full Name:
    richard jaffe
    #4 rickjaffe, May 21, 2005
    maybe that's it, I'm idling closer to 600 to 700; it's no problem without air, but the a/c shuts it off. the other thing I've notices is that on start up, if I don't sit in the car and give it gas for a long while, it will die; I think that's related because I don't think I would have that problem if it were idling at 900.

    btw. unscrewd the cover for the carbs; was expecting to find the air filter; where is it? also partially removing the cover seemed to rip a foam rubber gasket; then just put back the 4 wing nuts and decided not to mess with it; I
     
  5. rickjaffe

    rickjaffe Formula Junior

    Mar 6, 2005
    363
    houston
    Full Name:
    richard jaffe
    #5 rickjaffe, May 21, 2005

    do where is the idler adjustment?
     
  6. ham308

    ham308 Formula Junior

    Nov 3, 2003
    358
    NE Switzerland
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    Richard Ham
    #6 ham308, May 21, 2005
    Last edited by a moderator: Sep 7, 2017
  7. dinogt4guy

    dinogt4guy F1 Rookie

    Oct 31, 2004
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    Kurtis Fordice
    #7 dinogt4guy, May 21, 2005
    Thats the screw"A". I was talking about, but had no way to post a pic from my work shop manual. There is the same screw on the carb in front (toward firewall) of the one pictured. They both must be rotated the same ammount. I'm reading straight from the manual as I'm typing.

    Kurt
     
  8. gerritv

    gerritv Formula 3

    Jun 18, 2001
    1,400
    St Catharines
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    Gerrit
    #8 gerritv, May 21, 2005
    Hi Rick
    once you get the top cover off, there is supposed to be an air filter around the periphery. If not, then you should get one to protect your engine from grit in the cylinders.
    Tav 12 in the parts manual on http://dino308gt4.com shows item 10 as the air filter. K&N has them.
    Idle should be near 1000.
    You should join www.owners.ferrari.com as well to get the downloadable owners manual. It has illustrations of the carbs and the idle adjustment. Also in the WSM on my site.
    I must agree though that setting them up takes some courage, then patience and skill. Much of what you need to accomplish after doing the balance of air flow (using an airflow gauge) is by sound, quite subtle differences.

    Gerrit
     
  9. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,651
    San Carlos, CA
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    Mitchell Le
    #9 yelcab, May 21, 2005
    600-700 rpm warmed up is quite low.

    Assuming that all carbs had been synched before, and that your tachometer is trustworthy, adjust screw A (one for rear bank, and one for front bank) the same amount. 1/2 turn or more until your rpm reads 900-1000.

    Air filter is inside the black box over the carbs. You must have one, and it is easy to replace. Just remove the four wing nuts, and pop out the top.
     
  10. patpong

    patpong Formula 3

    Jul 6, 2004
    2,274
    Bangkok, Thailand
    Full Name:
    Patpong Thanavisuth
    #10 patpong, May 25, 2005
    I have very similar problem with my 308 carb...stalling with a/c on at traffic. But it does not stall right away. It stalls when stop for about 10 minutes up when the rev start to go down...down then die. The rev with a/c on is 950 rpm. and 1200 when a/c off...

    The screw A on the front bank is impossible to see or reach without lift off air filter cover...

    please advise..
     
  11. Lusso5

    Lusso5 Karting

    May 2, 2005
    69
    Houston, Texas
    #11 Lusso5, May 25, 2005
    Check the tension on your drive belts.

    I would also do a carb rebuild , if you haven't already. The rebuild kits are inexpensive.
     
  12. lusso64

    lusso64 Formula 3

    Apr 12, 2004
    1,535
    Simi Valley
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    David
    #12 lusso64, May 25, 2005
    If the idle is too low, just upping the idle adjust screws is not really addressing the problem. You should check the tune, balance, and synchronisation of the carbs. Check out this article for step by step instructions... http://www.r-design.net/308/index_e.html then go to tech tips #5. It really is quite easy once you understand what to do and have the right tools (ie synchrometer).

    A carb rebuild is always a good idea if it hasn't been done recently. While you're there, you should replace the throttle shaft bearings in the carbs with sealed units.

    Dave
     

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