Idle Speed setting dropping off. | FerrariChat

Idle Speed setting dropping off.

Discussion in 'Boxers/TR/M' started by Santino1, Feb 22, 2015.

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  1. Santino1

    Santino1 Karting

    Jun 4, 2014
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    Sacramento, CA
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    Daniel
    #1 Santino1, Feb 22, 2015
    Just finished my first major service, trying to get some ideas on troubleshooting my idle problem. Symptoms, driving the car, when I lift off the throttle, when the engine returns to it normal idle speed 1000 RPM's, it's starting to drop below 400 to 600 RPM's causing the engine to die. Also it's not happening all the time, some times it stays at it's normal Idle.
    The first time it did this, I was coming to a stop, and the engine died, had to really stand on the brakes, since I lost vacuum to the power booster on the brakes. Thanks'
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    #2 Steve Magnusson, Feb 22, 2015
    Assuming that it's a US version TR, two things you should check IMO:

    1. Operation of the throttle microswitch (for the RPM undershoot during closed throttle engine deceleration) -- although just being poorly tweaked up can give the same symptom, and

    2. The check valve and vacuum pump for the brake booster -- even if the engine dies, vacuum should still be present at the brake booster (because the check valve should close and preserve vacuum in the vacuum reservoir).
     
  3. Santino1

    Santino1 Karting

    Jun 4, 2014
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    Sacramento, CA
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    Daniel
    #3 Santino1, Feb 22, 2015
    Thanks' Steve, BTW My car is a 1988.5, does this year have the microswitch?
     
  4. ozziindaus

    ozziindaus F1 Veteran
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    Aug 16, 2012
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    Sam
    #4 ozziindaus, Feb 22, 2015
    Had this exact thing happen to me after I got mine back from a major. Turned out to be the battery terminals not clamped on enough.
     
  5. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Austin TX
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    Brian Crall
    #5 Rifledriver, Feb 22, 2015
    Yes



    Make sure there is slack in the throttle cable.
    Make sure the idle is at 750 rpm with both idle air bleeds totally closed with the banks balanced.
    Make sure both idle stop screws are equally supporting the linkage during the above.
    Make sure both air bleeds are screwed out until you have 1100 rpm with fans and A/C off with the banks balanced.
    Make sure you have 1.2%-1.4% CO, more than 15% CO2, less than 150ppm HC and less than 5% 02 with the O2's disconnected pre cat.

    Make sure when the throttles are opened via cable that the balance is even.
     
  6. Melvok

    Melvok F1 World Champ
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    #6 Melvok, Feb 23, 2015
    :D !!
     
  7. ago car nut

    ago car nut F1 Veteran
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    Aug 29, 2008
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    David A.
    #7 ago car nut, Feb 23, 2015
    Check the O-rings on the injectors. If they are hard, they can leak vacuum around the fuel injectors and cause erratic idle.
     

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