348 - ECU screeching/Buzzing sound | FerrariChat
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348 ECU screeching/Buzzing sound

Discussion in '348/355' started by Ravens_Shadow, Feb 15, 2025.

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  1. Ravens_Shadow

    Ravens_Shadow Karting

    Jul 18, 2022
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    Fuquay-Varina, NC
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    Nick Seavert
    #1 Ravens_Shadow, Feb 15, 2025
    Have the later gen motronic 2.7 ECU's in my 348 and when I was on a drive in fairly hot weather for a few hours, and near the end the ECU's were both screeching or buzzing. The buzz was a similar sound to the buzz you hear when you leave the door open with the key in the ignition, just quieter. I've been running the car without the covers on the ECU for a while just for quick CEL diagnosis. I didn't notice anything wrong with the car as I was driving it, just the noise seemingly getting worse. Let the car cool off for 30 minutes and when I cranked it back up, they were started buzzing pretty quickly. Haven't cranked it since last weekend to see if it still persists.

    Any thoughts? ECU's about to kick the bucket?
     
  2. m.stojanovic

    m.stojanovic F1 Rookie
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    Miroljub Stojanovic
    #2 m.stojanovic, Feb 15, 2025
    Are you sure that the buzzing comes from the ECUs? Perhaps you can verify this with a mechanic's stethoscope.

    Otherwise, the things on the engine that produce buzz/hum are the Idle Control Valves (ICV). This buzz is normally not easily heard but it could, perhaps, get louder if the ICVs are pretty worn. When your buzz appears, you can listen at the engine bay, with the engine not running but ignition "on", to check whether the buzz is maybe coming from the ICVs.
     
    IvanRico likes this.
  3. redwedge

    redwedge Formula Junior

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    Steve C
    #3 redwedge, Feb 16, 2025
    ...if you haven't got a stethoscope, a length of hose isn't a bad substitute.
     
  4. JM280z

    JM280z Formula Junior

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    #4 JM280z, Feb 16, 2025
    Could it be a relay? Relay and fuses are cheap and easy to replace. Just make sure to buy quality, but they’re still cheap in comparison to normal work on these cars.
     
  5. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #5 fatbillybob, Feb 16, 2025
    WTF! Never heard that one before and I have fixed just about everything on a 348 at least once.
     
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  6. JM280z

    JM280z Formula Junior

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    #6 JM280z, Feb 16, 2025
    Do they have cooling fans and it’s just a bad fan? Could it be the sound of an electrical short?
     
  7. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
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    #7 Mitch Alsup, Feb 16, 2025
    Thought #1: Do not run the ECUs with the covers off--you do not want a piece of road debris to land in the ECU and short out wires.

    Thought #2: The transistors used to fire the ignition coils can vibrate audibly just from the energy of firing the ignition coils.

    Good Luck
     
    JM280z likes this.
  8. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #8 fatbillybob, Feb 16, 2025
    I call bs on that. Does not happen can't happen
     
  9. JM280z

    JM280z Formula Junior

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    #9 JM280z, Feb 16, 2025
    On what?
     
  10. m.stojanovic

    m.stojanovic F1 Rookie
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    #10 m.stojanovic, Feb 17, 2025
    Just to add:
    Thought #3: The Flux Capacitors are playing up when they get hot.
     
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  11. JM280z

    JM280z Formula Junior

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    #11 JM280z, Feb 17, 2025
     
  12. Ravens_Shadow

    Ravens_Shadow Karting

    Jul 18, 2022
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    Nick Seavert
    #12 Ravens_Shadow, Feb 17, 2025
    Drove the car for 4 hours yesterday and didn't hear the buzzing noise at all. If it pops up again I'll see if its an ICV or actually an ECU buzzing. I don't have a stethoscope, but do have tubing I could use. I did stick my ear up to it directly when it was buzzing and it was pretty loud. But if ICV's are roughly in that area behind the firewall, maybe they could be the cause.

    I'm referring to the vented leather covered pieces that cover the ECU's behind the seat, not the metal ECU casing itself. Still risky?
     
  13. JM280z

    JM280z Formula Junior

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    #13 JM280z, Feb 17, 2025
    I drive with those leather covers off to access the button when driving too. I’ve been working to have zero CELs, not easy on these cars apparently. During the fall, I do get leaves all around the cabin, but overall, I’m not concerned. Maybe I’m wrong, the covers are there for a reason.
     

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