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Decelerating over a bump causing Roadster to lurch forwards

Discussion in 'Roadster' started by alang_94526, Jul 5, 2017.

  1. alang_94526

    alang_94526 Member

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    My 2010 roadster has always had this issue and I'm not sure if it happens on ALL roadsters or just mine.
    On a flat road, when I decelerate the regen braking kicks in and you see the Amp gauge swing to charging (OK, that's all pretty much as you would expect).
    When you do the same thing but go over a bump in the road, the car lurches forward, the regen disengages, the Amp gauge swings to the right and the TC light flicks on for a second. The loss of regen braking makes it feel like the car just accelerated forward.
    This doesn't sound like its meant to be this way but this is a "basket case" according to Elon Musk, so maybe it's just the way it is.

    I've tried disabling TC but it has no effect.
     
  2. BrettS

    BrettS Member

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    I don’t have a roadster, but I did have a Prius before my model S and the Prius suffered from the same issue... regen would cut out when the car went over a bump or rough pavement as you were breaking. I think it’s a standard issue for cars with regen on the brake pedal because the wheel speed sensors start getting unusual readings, so the car stops doing regen to make sure the wheels don’t lock up and cause loss of control.
     
  3. wiztecy

    wiztecy Active Member

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    It can be a combination of things or even limited just one. Traction Control and ABS. Either can send your car lurching forward when the car hits bumps which causing one or multiple wheels to spin freely and the known calculations it uses to be off. I turn TC off when I drive spirited to prevent any surprises. ABS, well its just the nature of the beast. Just have to be aware of the roads your driving on. Any car with ABS will do the same. Thing is regen is very aggressive in the Roadster, so when TC shuts down it acts as if you're accelerating. Also the crappy stock brake pads and rotors don't help hence why I upgraded them early in the game.
     
  4. dhrivnak

    dhrivnak Active Member

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    This happens to me in my Roadster and even to a lesser degree in my Volt
     
  5. alang_94526

    alang_94526 Member

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    Thanks all. I can relax now, consider this normal behavior and no longer anticipate the day when the wheels are going to fall off.:(
     
  6. wiztecy

    wiztecy Active Member

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    Always good to ask and it felt weird to me as well when I also experienced it... Still driving #531? Hows it holding up?
     
  7. alang_94526

    alang_94526 Member

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    Still driving it. I was able to find someone to service it for me and they had to jump through a few hoops to get parts. The downside is it takes weeks to get serviced so I try to get things done when on vacation.
    I still wait for something catastrophic to happen to it and won't be able to fix it. But that's for another day
     
  8. wiztecy

    wiztecy Active Member

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    Glad you found a way to keep it on the road and surely appears you're using it. Thanks for the update.
     
  9. TEG

    TEG TMC Moderator

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    Was driving a friend's roadster recently and had the same thing happen when I hit a bump. It was downhill with heavy regen so the "regen reboot" caused a brief moment of panic but then all was well again.
     
  10. MileHighMotoring

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    I've felt this in every vehicle with regen braking, including traditional hybrids.
     
  11. wiztecy

    wiztecy Active Member

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    Its really bad when this happens while your racing through corners and braking late, can make you overshoot your turns for sure. Best to disable TC when you know you're having fun and when you also know the car.
     
  12. alang_94526

    alang_94526 Member

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    And as soon as I said it, it broke down ;p
    DMC FW: PhaseC OverTemp fault

    Luckily my service guy was able to fix it and did a full drive and PEM service at the same time.
     
  13. wiztecy

    wiztecy Active Member

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    Happy you fixed it. What was the issue and what did they do to resolve it? Was this a fault during an attempt to charge?
     
  14. alang_94526

    alang_94526 Member

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    Accumulation of dirt in the fans causing it to fail, hence causing overheating apparently. He stripped the whole drivetrain and cleaned it all out. Apparently it was a dirt-fest.
     
    • Informative x 1
  15. wiztecy

    wiztecy Active Member

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    Gotcha, you have the 2.0 if I recall. Yes, the 2.x PEM / Fan design pics up everything that's on the road unfortunately. You do have to keep on it annually and monitor your PEM temps in the VDS screen for any signs of restricted cooling flow to the PEM.
     
  16. alang_94526

    alang_94526 Member

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    Yes you're right on all counts.
     
  17. gavine

    gavine Petrol Head turned EV Enthusiast

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    BMW i3 does this too
     
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