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Engine Stalling

Discussion in 'Boxers/TR/M' started by Hipporacer, May 17, 2023.

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  1. Hipporacer

    Hipporacer Karting

    Jun 26, 2021
    55
    Springfield IL
    Full Name:
    Julia M Stapleton
    #1 Hipporacer, May 17, 2023
    For a while now, I have noticed that if I going at a decent speed in 5th gear and coming up to a turn, that if I push the clutch pedal down and hold it down to shift the revs fall. They will fall below 1k and the engine will die. Once the downshift is completed and the clutch pedal let up the engine restarts itself. This also seems to correlate with the AC being on. But it is possible that has nothing to do with it. I'm sorry if that doesn't make sense. I know how to drive a manual but I don't understand the inner mechanisms behind the idea. It doesn't bother me too much because I've just adapted my driving style to avoid it. Instead of using the clutch coming up to a turn I throw the car into neutral and then complete the shift.

    This is an 87 testarossa BTW.
     
  2. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,572
    San Carlos, CA
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    Mitchell Le
    #2 yelcab, May 17, 2023
    You probably are due for a tune up where the idle speed is checked and set, the fuel pressure is checked, and the fuel mixture is set.
     
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
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    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    #3 Steve Magnusson, May 17, 2023
    What version? US (engine family F113A040), early euro (engine family F113A), late euro (engine family F113B), something else?

    Some of the pros here have reported setting the TR warm idle a little higher (1050~1100 RPM) with AC "off" so that it doesn't dip too low with AC "on". Have you ever measured your warm idle with something more accurate than the dash tachometer? What does you warm idle RPM with AC "off" and AC "on" show on your dash tachometer?

    Does the engine RPM always "undershoot" during deceleration (i.e., go below 1000 RPM), but just doesn't always stall?
     
  4. lagunacc

    lagunacc F1 Rookie
    Rossa Subscribed

    Aug 24, 2013
    4,402
    #4 lagunacc, May 17, 2023
    From her prior posts on this, it sounds like the two engine halves not being balanced - surging unstable idle etc.
     
  5. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    southwest Germany, France ( Alsace ) and Thailand
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    romano schwabel
    #5 turbo-joe, May 17, 2023
    does the engine also shut off when you come to a red traffic light?
    does the engine idle in cold, little warm and warm condition?
    I ask because you write it only happens when shifting from 5th to 4th, so I wonder
     
  6. 2008F430

    2008F430 Karting

    Apr 30, 2020
    106
    St Augustine
    #6 2008F430, May 17, 2023
    I have an 87 and had the same issue. Turns out the idle was just set a little too low.


    Sent from my iPhone using FerrariChat
     
  7. Hipporacer

    Hipporacer Karting

    Jun 26, 2021
    55
    Springfield IL
    Full Name:
    Julia M Stapleton
    #7 Hipporacer, May 19, 2023
    Can someone give me instructions on how to turn my idle up? On my mr2 it's just a screw, but I don't know where they are on the testarossa engine...I think there's two of them at least...
     
  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    Steve Magnusson
    #8 Steve Magnusson, May 19, 2023
    Last edited: May 19, 2023
    I think it highly unlikely that your problem is as simple as just "turning up the idle", but, if you want to try that, you would open each air bypass screw some more, but you should really confirm/deny if the intake vacuum in each plenum at warm idle is the same now -- if it isn't, that's just another sign that your TR is not tweaked up properly in the first place. I.e.:

    1. Measure the intake vacuum in each intake plenum at warm idle (using the same vacuum gauge to eliminate any gauge differences) -- they should be the same (if not equal = the whole thing needs to be tweaked up properly).
    2. Open each air bypass screws to increase the warm idle RPM - while keeping the intake plenum vacuums the same
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    However, you should also ensure that the idle throttle microswitch on the 1/6 throttle body is working -- just unplug it at warm idle = the warm idle speed should increase by 200~300 RPM. Then plug it back in = the warm idle speed should drop back to what it was. This is something that needs to be working correctly before it can be tweaked up correctly. Likewise, (if a US version F113A040 or late euro version F113B) the Protection Relay system need to be working correctly. Almost unfortunately, if either of these systems are not working correctly, the system can be tweaked up to run sort of OKish when warm, but it's not right. Attached is a summary for how to tweak up a US F113A040 TR.
     

    Attached Files:

    turbo-joe likes this.

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