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in shock...

Discussion in 'Z3 Roadster & Coupé' started by David Cullen, Nov 19, 2014.

  1. David Cullen

    David Cullen Zorg Legend
    Supporter The M44 Massive

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    the runaway car issue has been resolved ;-)

    thank you all for your help on this, i understand it was a bit of an unusual one and i am in shock as to what the problem was, never would have thought of it. I have been trawling web posts the past few days looking for people with similar issues to mine, none quite hit the nail on the head till this evening when i spotted a thread with a guy explaining the exact same symptoms as i had, nobody on the forum could figure it out and as i read through the posts page by page i was beginning to lose hope but in the end he posted this...

    THE SOLUTION
    Check you rim sizes.
    No you are not misreading this post. The solution to my problem was changing rim sizes. Hats of to an awesome local mechanic who suggested tire sizes could be the problem. Recently I had swapped the rear wheels out for a pair off another car to save money and be better prepared for the rainy season. This "new" pair, where a much larger rim size and caused the speed sensors on the other wheels to go out of sync. I simply put back on the factory rims and it was good as new. Now I just need to buy new tread for the rims.

    it clicked with me straight away as i had changed my tyres a few days ago, got a set with 55 wall on the back and when we went to put the 55 on the front they didnt fit so we put back on the old tyre which was a 45 wall
    so running a 55 rear and 45 front was messing things up, car was trying to catch itself up, not quite sure how that is, maybe someone can explain :) but after reading the thread i went out and changed the new wheels back to the oem, which had all same tyre sizes and the car ran perfect....
    still a bit in shock here but glad it has been resolved and i think we maybe all have learnt something new today ;-)
    thanks
    dave
     
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  2. oldcarman

    oldcarman Zorg Guru (V)
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    Hi, found it, glad it was so simply!! JIM
     
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  3. Aceman

    Aceman Moderator
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    Wow I have never heard that one before and like you would not have twigged that one. Glad you have sorted and weren't going crazy trying to look for a sticky throttle when it actually didn't exist.
     
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  4. miller1098

    miller1098 Zorg Guru (V)
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    RESULT!:)
     
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  5. Lee

    Lee Zorg Guru (V)
    British Zeds #ZedShed M Power

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    Very satisfiying, they must of been quite a difference in rim size.

    Just think you have the cleanest throttle body z3 around at the moment ;)
     
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  6. GazHyde

    GazHyde The Gaz Monkey
    Staff Member Administrator Global Moderator British Zeds

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    Great news that you have found a solution. :drinks:
     
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  7. jonco

    jonco Zorg Guru (III)
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    Glad you have sorted it David but, out of interest and as Lee says, what were the different rim sizes? The 45 and 55 you quote are presumably the side wall heights which are a % of tyre width.
    I would have thought the ASC would have kicked in if they were that far out or have I got it wrong? Can somebody please explain?:confused:
     
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  8. David Cullen

    David Cullen Zorg Legend
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    @Lee @jonco
    yes Lee, throttle body is spotless lol ;-)
    Jonco, the wheels were the same, 17" all 4 and both tyres were 235 wide but the tyre wall on rear were 55 and front were 45 so i guess the system didnt like it and ASC never flashed or anything, just glad it sorted, i could have been looking a long time before i twigged that one lol
    thank god for internet ;-)
     
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  9. t-tony

    t-tony Zorg Expert (I)
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    Happy you got to the bottom of it Dave, I guess you'll be visiting this guy with a bottle at Christmas?:)

    Tony.
     
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  10. David Cullen

    David Cullen Zorg Legend
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    Ha thanks Tony, he is in the states so I guess not :) just happy its sorted and was a simple solution ;-)
     
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  11. Brian4

    Brian4 Zorg Guru (IV)
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    Just checked and the 55 profile is 147mm (5.7" for us old uns) bigger in circumference then the 45 profile so would have thoght the ASC would have played up but not affect the throttle but the ASC is wired into the throttle body so guess is was doing something. You live and learn and glad it is sorted now.

    PS me rambling to myself as I was typing.
     
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  12. t-tony

    t-tony Zorg Expert (I)
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    No worries mate, just send me the bottle;) and I will try my very best to find this guy for you in April:)

    Tony.

    ps. The bottle mightn't be quite as full by then though.=))
     
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  13. David Cullen

    David Cullen Zorg Legend
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    yes Brian, obviously the ASC comes in to play but in an undesirable way :-/
    yea Tony sure see what you can do :p
     
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  14. Drew

    Drew Regular Member
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    I have heard of this similar occurrence on 4wd but not on 2wd.
     
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