Stalls at Idle when the AC is turned on | FerrariChat

Stalls at Idle when the AC is turned on

Discussion in 'Mondial' started by Javelin276, Oct 11, 2018.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. Javelin276

    Javelin276 Formula Junior

    Jan 16, 2005
    512
    Idaho
    Full Name:
    Thor Zollinger
    #1 Javelin276, Oct 11, 2018
    Hey guys, my Mondial-8 is stalling when I turn on the Air Conditioner at Idle. Anyone know anything about this? I can't find anything in the Shop Manual on how this is controlled. I'm thinking of installing an IAC Valve (Idle Air Control) from another car to fix the problem.
     
  2. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    #2 spicedriver, Oct 11, 2018
    Last edited: Oct 11, 2018
    Car should be in a good state of tune. All ignition components good. No clogs in the fuel system. Clean injectors. Correct control and system pressures. Correct idle mixture. Correct idle speed. Air screw, and throttle valve adjusted properly. Note to adjust idle speed with the air screw, and not the throttle valve (throttle plate position).
     
  3. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,645
    Canada
    #3 moysiuan, Oct 12, 2018
    The idle ideally should be about 1,050 rpm after warm up. It should not be lower than 900rpm, or the system will not have sufficient flows to work properly. The ac load will take off about 150rpm, so if you are below the 900rpm level with ac on this might cause a stall. The tach may not be accurate to this precision, but at least start there. This is a higher idle than for many cars, but erring on the high side is where you want to be for this Bosch FI system.

    I have a 3.2, so I am not sure where the air flow adjustment for idle is on the 8.

    The IAC valve is only affecting cold start idle, and moderates it down as the car warms up, so should not be related to the ac load issue you are describing.
     
  4. Javelin276

    Javelin276 Formula Junior

    Jan 16, 2005
    512
    Idaho
    Full Name:
    Thor Zollinger
    #4 Javelin276, Oct 12, 2018
    Thanks guys. I'll make some adjustments and I'll see where I end up. I'm still considering installing an air bypass valve which opens when the AC compressor goes on if this doesn't alleviate the problem.
     
  5. Wade

    Wade Three Time F1 World Champ
    Owner

    Mar 31, 2006
    32,793
    East Central, FL
    Full Name:
    Wade O.
    #5 Wade, Oct 13, 2018
    I'd try to find a fix first before circumventing the problem.

    Does your A/C system actually work? Does it's clutch engage? If so, maybe your compressor is dragging?
     
  6. Javelin276

    Javelin276 Formula Junior

    Jan 16, 2005
    512
    Idaho
    Full Name:
    Thor Zollinger
    #6 Javelin276, Oct 13, 2018
    To answer your questions, yes the AC works, yes the clutch engages, and it's behaved this way the entire 10 years that I've owned the car. I've had my mechanic work on it too, but he couldn't really fix it to my liking either. I just decided there had to be a better way. After digging through the shop manual again, I've come to the conclusion that Ferrari simply raised the idle speed. More modern cars use an Idle Air Control Valve controlled by the computer to adjust things. These older cars don't have a computer, so I've pretty much decided to engineer my own mod.
    I've located the AC clutch wire in C4 pin 2, so once the cartridge valve and fittings come in next week I'll install the valve, wire it in, and test it out. It may need a second valve in the line to allow me to adjust the flow, but I'm confident it will work just fine. I'll be adjusting everything else today prior to trying that.
     
  7. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    #7 spicedriver, Oct 13, 2018
    Sounds like the motor has never been tuned up properly. It is not normal for the motor to stall when the A/C pump engages. I would start by measuring the system and control pressures.
     

Share This Page