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A3 Quattro and ESP

lil_coz Feb 13, 2008

  1. lil_coz

    lil_coz Active Member

    I've just been wondering at how the system works with the ESP system turned off. I know when the ESP is on that it shifts power to the back when the front loses grip etc, but what happens when you turn the ESP off? I remember someone telling me that in normal conditions the power delivery is 70:30 front to back. Or did I dream this up? Anyone know what the two extremes are?

  2. s3mike

    s3mike Member

    As far as I know the ESP has nothing to do with power transfer.

    The Haldex controller does the power transfer based on throttle angle, speed and front wheel slip. I'm not sure if there is a 'normal' power transfer as it will vary constantly depending on conditions. At high speed with no front wheel slip I thought it was 100% fwd ( could be wrong though ! ).

    The ESP has two parts really, traction control (ASR/EDL) and ESP itself. With the system on the ASR/EDL will brake any wheel that spins ( front or rear ) and can reduce engine power to stop wheel spin - with if off it won't intervene. With it off you could get all 4 wheels spinning on ice or very slippery roads as the hadlex will distribute the power to all 4.

    The ESP part takes into account steering angle, yaw rate, and wheel speeds to stop the car from understeering or oversteering. So if you go into a corner to fast and start to understeer it brakes the inside rear wheel and can but power to bring the car back on line. It does this for oversteer to by braking the front wheels as needed.

    As far as I can tell the ESP part is never completely disengaged - so with ESP off you get on ASR/EDL plus a later acting ESP. It lets the car slide more before intervening but will still intervene in extreme situations. I've never seen the light flash or felt intervention with the system off though - but I probably wasn't trying hard enough!

    I'm sure I'll be corrected if my understanding is wrong!
  3. lil_coz

    lil_coz Active Member

    Thanks for that Mike. I thought I read in the manual that the power transfer is part of the ESP and was wondering what happened if it was turned off. I havent got the manual at hand so cant double check if I read it right or making it up!

    It makes sense that its not part of it from what you've just said. Thanks again for the info :icon_thumright:

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