SL 55 AMG Two strange electrical issues for diagnosis - video shows issues

Discussion in 'General Discussion' started by laurensparsons, Mar 31, 2014.

  1. laurensparsons

    laurensparsons Active Member

    Messages:
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    Car:
    VW
    Hello, I am having some issues with an 2006 Sl 55 with 22k miles, not been driven much this year, only a few miles,

    Basically there are two issues that i think are likely linked;

    1. First issue is in manual gear mode, you have very little control over the gearbox, it sometimes lets you change gear but this is sporadic and it drives just as if its in 'S'

    2. After a quick burst of power and breaking, 'esp inoperative' shows up on the dash and the cars goes into limp mode with irratic idle until you restart then the problems fixed, Video of the fault is linked here(turn volume up)


    Fast, Free Video Hosting & Video Sharing - VideoBam

    More detailed explanation found here:

    1. Manual gear control does not appear to be functioning properly, generally the car overrides your manual selection, this appears to be sum what intermittent and unpredictable, (please test drive) the paddle shifts seems to be worse than the gear nob selector, initially i thought that this was just the characteristic of the vehicle however after reading the brochure, i believe that when in manual ‘M’ mode the car should not perform its own gear changes at all, please let me know what you feel?

    2. After very hard high rpm, low gear, full throttle acceleration , then immediately after heavy breaking the ‘ESP inoperative’ warning appear on dash (please test drive) - the engine then looses nearly all its power and the throttle appears to do very little, even full throttle will only cause the car to creep along at 15mph, engine idle with no foot on accelerator also flutters around highly at around 1500rpm and a slight gradual depression upon accelerator will infact cause the revs to drop slightly however the engine is very unstable and flutters up and down a wide tolerance of a few hundred rpm, one time the engine management light came on during this event and stayed lit afterwards for quite some time even after restart, however an engine restart will always immediately remedy the problem and remove the ‘ESP inoperative’ warning on dash and return the engine to its normally idle rpm, but for about a minute after restart the engine still lacks most of its power say its only has about 30% power after the restart, but this soon returns to normal. The last time strangely the 'bonnet up’ warning flashed up on the dash whilst in hard acceleration at high rpm, then quickly disappeared, its like the computer electrical system goes mad under hard acceleration or breaking, (Please see video i took which shows this issue,Fast, Free Video Hosting & Video Sharing - VideoBam
     
  2. cb1965

    cb1965 Banned

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    No video links in your post, but firstly two questions.

    1) you say the car has not been drivemn much, are both batteries in tip-top condition as this could be partially an electrical issue althiugh that is an outside chance really!

    2) Has the car ever been re-mapped or tuned as the ESP/limp home mode after hgh revs would indicate the engine reading its sensors incorrectly... this could be down to the map!
     
  3. OP
    OP
    laurensparsons

    laurensparsons Active Member

    Messages:
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    Feb 19, 2011
    Car:
    VW
  4. cb1965

    cb1965 Banned

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    OK next I would check one of two things.

    Has the airbox to throttle gasket become damaged and/or partially dislodged?

    Is the pedal position sensor functioning correctly?

    To answer these questions you will likely need to take it to an independent specialist (you can try a Merc dealer, but you will need deep pockets and to be lucky finding one that can diagnose the problem correctly without just chucking parts at it).

    If it was me I would look firstly at the pedal position sensor as the two issues you are experiencing could both be related to that.
     
  5. miro

    miro Hardcore MB Enthusiast

    Messages:
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    Location:
    Sydney NSW Australia
    Car:
    W203 slightly modified
    CANBUS-C sounds like it is faulty.
     
  6. RattlerRattler

    RattlerRattler Hardcore MB Enthusiast

    Messages:
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    Joined:
    Sep 26, 2013
    Car:
    SL 55
    Did you get any warantee when you bought the SL? Did you buy from a specialist dealer? And as you've only owned for a short time, the seller should offer some after-sales service here to at least assist with the diagnosis.
    Tim
     
  7. JasPed

    JasPed New Member

    Messages:
    20
    Joined:
    Feb 12, 2014
    Hi, could possibly be Air Mass Meter or Potentiometer (Accelerator Pedal) or both. Had the same problem as you are describing 2 years ago.
    Not too expensive to fix £118 for Air Mass Meter and about £130 for electronic Accelerator pedal from Mercedes Benz dealer. Add on about an hours labour for both items to be replaced and should be good to go. After this problem was diagnosed on Star Diagnostic on my SL 500 she ran like a dream !

    Regards
    Jason P.
     
  8. JasPed

    JasPed New Member

    Messages:
    20
    Joined:
    Feb 12, 2014
    Just had a look at your video and it shows very similar problem as what I had. When you you restart the engine you are still in limp mode which will get you home as long as you don't hit the accelerator to hard, I am pretty certain it is the 2 components I have described in above post.
     

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