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Traction Control/Swaying under Firmware v4.2 ?

Discussion in 'Model S: Driving Dynamics' started by Vger, Jan 26, 2013.

  1. Vger

    Vger Active Member

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    Last night, while on a road trip to beautiful Tofino on the west coast of Vancouver Island, we got updated from 4.2 (.41) to 4.2 (.42). The download seems to have occurred WHILE driving the 4 hours here, and then I did the update in the hotel parking lot.

    Today I was giving friends rides and found what might be a significant improvement in this release-- traction control stability. I did a number of 0-60 runs on dry to damp pavement and with the Pirelli winter tires. I found that the traction control seemed much more stable. Several times before (on 4.0 or 4.1), I found that the car would fishtail notably doing a full-power start. I was actually rather unnerved by it. Now, the starts are very stable, with little or no wheel spin, and even in I am at the limit of adhesion, and there is some wheels spin, the car remains absolutely stable at blasts straight ahead.

    BTW, I think I may have sold my two friends on either an S or an X each!
     
  2. Zapped

    Zapped Model S - PURE EV

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    With TC did you still get 0-60 in 4.4 ?
     
  3. Vger

    Vger Active Member

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    Had no good way to measure, and without the high-performance tires and a bone-dry and warm road surface, I would not expect that time. It "felt" more like 5 seconds to me. I was highlighting the apparent improved stability and balance.
     
  4. patp

    patp Member

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    That's exactly the feeling I got today. First, I saw that regen was feeling different. Then I felt the car was much more stable / easier to manage during acceleration on slippery roads. Also, I felt that T/C was kind of letting the wheels spin more.

    So I'm not alone! I've asked Tesla if I was crazy or not.
     
  5. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Of course that has nothing to do with the traction control :)

    Sorry, couldn't resist.
     
  6. Jeeps17

    Jeeps17 Cath Jockey in a P85

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    Are you saying that we may have a snow-friendly(er) car?

    Bring on the snow storms! :biggrin:
     
  7. patp

    patp Member

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    The weather conditions are not the same (very cold / no snow) these days so I can't really compare. But I FEEL something different. It's like the car is easier to handle under acceleration (feels a little bit less RWD). I hope I'm not dreaming.
     
  8. Jeeps17

    Jeeps17 Cath Jockey in a P85

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    It's a start... and since you've driven the car for a little while, I would tend to believe your perceived change in driving dynamics.
     
  9. RedSoxDoc

    RedSoxDoc Member

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    Since updating my Model S Performance to 4.2 there seems to be (dare I say) too much torque! The wheels are spinning more on rapid acceleration. Then after a second or two of that it launches! It clearly changed with the update and the update info said there was indeed an adjustment to the acceleration. I thought that the performance was a little better with 4.1. There has even been some fish-tailing secondary to the increased torque. Anyone else notice this?
     
  10. ChadS

    ChadS Petroleum is for sissies

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    I'm not positive, but I don't think there is any more torque or better performance - I think it just applies the torque without you having to press the pedal quite as far (that would not matter if you just floor it). I also believe it feels like it applies the torque sooner after you press the pedal, rather than waiting a tiny bit to see if you change your mind.

    So if you're used to pressing the pedal a certain amount and it used to grip, it is possible that it now spins with the same amount of pedal input.

    I've noticed less fishtailing (not that there ever was a lot given the power I was putting down in wet conditions); but if you weren't spinning the tires at all before and now you are it does make sense that you're seeing more fishtailing. Did you happen to change tires or anything? My 19's were very slippery when I first got them.
     
  11. brianman

    brianman Burrito Founder

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    I was patiently waiting for 4.2, and then you guys have to start talking about new candy:
     
  12. sfriedrich

    sfriedrich Member

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    "Anyone else notice this?"

    MS Perf here. 21" wheels. Yes. Operates much closer to traction limits IMO. Still brings a grin to my face EVERY time though... after 2 1/2 months.
     
  13. Jcmason

    Jcmason Member

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    I updated to 4.2 on Saturday, then yesterday drove 270 miles round trip to go skiing in the Catskills (NY). On the way back, driving at 55mph, I needed to accelerate past a car in the middle lane before another car I could see coming up behind me in the left lane, so I floored it. My Model S quickly accelerated up to around 75mph, but I also felt it start to sway left and right, as though it was about to take off. I backed off the accelerator and moved back into the middle lane. No damage done, but it felt a little too close to being out of control to be entirely comfortable. Has anyone else experienced this and/or have an explanation for what happened?
     
  14. Doug_G

    Doug_G Lead Moderator

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    It's basic physics - when you floor an extremely powerful RWD car, the weight transfers to the back wheels. This helps traction for acceleration, but reduces the grip on the front wheels. The best way to avoid this sort of thing is to be very smooth on your inputs, both accelerator and steering.
     
  15. Jcmason

    Jcmason Member

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    #15 Jcmason, Jan 28, 2013
    Last edited: Jan 28, 2013
    @Doug_G Thanks, makes sense. I've not noticed this effect as much previously, so thought it might be related to the discussion above about changes to torque in the 4.2 release. It could just be that I accelerated a little harder than normal though. I didn't actually floor it btw, just accelerated fairly hard. Your explanation stands to reason all the same. I'll try to be a little smoother in future :tongue:
     
  16. nolngrgrsngslde

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    WADR, I have to disagree. The weight transfer to the back wheels would have to occur via some rotation of the center of gravity around the rear wheel axle. Being that the center of gravity is almost at level with the rear axle (battery being so low), it would take a humongous torque to lift it and rotate the battery weight enough to make the front wheels feel so light as to loose grip. A regular car is another story.

    IMHO, I think that Tesla's Stability Control needs some more work.

    Having said that, i am not a physicist, nor a Mechanical engineer...
     
  17. aaron.s

    aaron.s Member

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    John, All -

    Now that you and others are posting this - I have to say it happened to me too. Yesterday on my way back from the Supercharger, when I let my friend do some spirited acceleration (flooring the accelerator) on the Merritt we felt it (left and right swaying) several times during fast, passing acceleration. I thought it was him not being used to the car and lightly moving the wheel back and forth - but now I don't think it was that - but actually the 4.2 update.

    I havent personally done any "flooring" since upgrading to 4.2, so I haven't noticed it.... If Tesla did some tweaking to the traction control - perhaps this is a bug....

    Aaron
     
  18. Hank42

    Hank42 Member

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    I can confirm the same experience under very similar conditions (60-90MPH). But this was with 4.1. I still notice it with 4.2. A little scary, because you, the driver, expect to compensate but something does it for you and then you, the driver, over-react. Very disconcerting. I don't like it. Can we turn that damned stabitrack off, EASILY?
     
  19. dtich

    dtich #P708

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    #19 dtich, Jan 28, 2013
    Last edited: Jan 28, 2013
    maybe i'm imagining, but i actually think i sense less of this in 4.2. in quick lane changes previously i would feel what you both are describing acutely, and not like it, doesn't feel 'on rails', feels floaty, more like a cadi. however in the days since 4.2, with no change to my driving habits, i don't think i'm feeling it quite as much. ymmv.

    edit: (alright, maybe not acutely, or floaty exactly.. but i feel it. at any rate, the car drives like a dream. but if we're discussing the finer points, let's discuss the finer points... :) )
     
  20. apacheguy

    apacheguy Sig 255, VIN 320

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    For the record, mine just got updated from 1.15.14 to 1.19.42 today. I'll try to steer clear of any hard acceleration while TM fixes the TC issue. :wink:
     

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