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Power drop

Discussion in 'A4/S4 forum(B5 Chassis)' started by Iceash, Jul 3, 2012.

  1. Iceash

    Iceash Member

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    Hi All,

    Yesterday while accelerating in 1st, for a second felt like an elastic band was attached to the back to pull me back! Now I was passing over 3 manhole covers so wonder if I might have just spun up a wheel to loose the push as such.

    It was very smooth de acceleration and came back incredibly quickly.

    Just wondered if anyone had this as well?

    Thanks,

    Ash
     
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  3. gen.heinz guderian

    gen.heinz guderian Well-Known Member
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    Did the traction control light flash?
     
  4. Iceash

    Iceash Member

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    I don't have traction control not that I know of. But now you mention it that's what it felt like.
     
  5. aragorn

    aragorn "Stick a V8 in it!"
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    You do have EDL though, which is active at lowish speeds. Probably spun up a wheel on the manhole and the EDL has jammed the brake on to stop it.
     
  6. Iceash

    Iceash Member

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    edl Whats that? Something that can be turned off? Was in first gear so sounds like that
     
  7. aragorn

    aragorn "Stick a V8 in it!"
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    Electronic Diff Lock.

    Older quatrros had a lockable rear diff, or an LSD in the rear axle and a lockable centre. When Audi developed the system in the B5, they went for a limited slip centre, and open front and rear diffs, presumably as a cost saving measure, and to make the car more "general public" friendly.

    The problem with this setup, is that in really low grip conditions, for instance snow or ice, because of the open diffs on each axle, you can end up having one wheel spin up and lose all drive as a result. The LSD in the centre can only bias torque, not speed, and the open diffs in each axle send the drive to the easiest wheel to turn, so you end up with say one front wheel spinning on a patch of ice and transmitting very little torque, and the centre diff cant really do much to help.

    To rectify this, they added a feature to the ABS system, which independently monitors the wheel speeds across each axle, and if it sees one wheel spinning a lot faster than the other, it assumes a loss of traction and applies the brake on the spinning wheel in an attempt to shunt power to the other side and to give the centre diff something to work with.
     
  8. Iceash

    Iceash Member

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    you never fail to impress me! So this is what happened to me then.
     

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