Engine not accelerating past 40mph

Discussion in 'Engine' started by Oteda, Oct 15, 2011.

  1. Oteda

    Oteda Active Member

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    I was driving quite casually for a while in my W221, and then when I finally got some space I decided to accelerate at around the 40 mark and noticed no power was felt, the rev meter almost stayed at 2 revs if not lower and the car slowly accelerated. I even put my foot down to the floor and this made no difference. Tried it in manual, same thing.

    Parked up and switched the engine off, after a while I started again and the problem had disappeared. Accelerating as normal. Any idea what it could be? I have a health check booked in next week and will see to it then, at the mo its driving fine.
     
  2. Harrythedog

    Harrythedog MB Enthusiast

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    You've gone into limp mode. Switching the engine off then on again sometime resets the problem. Could be a number of things causing this and a STAR diagnosis will determine what it is.
     
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  3. SPX

    SPX MB Club Veteran

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    Sounds like the MAF.
     
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  4. OP
    OP
    Oteda

    Oteda Active Member

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    So thats limp mode, thanks a lot. I did some research on signs and symptoms of a faulty MAF, and it does seem like that is what it is. My car hesitates to accelerate by about 2 seconds, and sometimes I feel a slight chug at 40mph. I have a health check up at Merc on saturday I will look into all of this. Anybody know a good mechanic in London who can just clean it for me would be appreciated.
     
    Last edited: Oct 15, 2011
  5. ucr

    ucr MB Enthusiast

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    Must be the cheapest S Class in the world to run
     
  6. artyman

    artyman MB Enthusiast

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    Silly question, but had you activated the speed limiter by mistake.
     
  7. hestonmob

    hestonmob New Member

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    london
    Car:
    mercedes benz c240 v6
    had a similar problem with my c240 just wouldn't respond. it turned out to be the air mass sensor.
     
  8. OP
    OP
    Oteda

    Oteda Active Member

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    Sep 3, 2011
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    No I hadn't. But I do believe it is the air mass sensor. My car was parked up for a while before I bought it and since the incident I gave it a good blast and its running better. I will look into getting the MAF cleaned and hopefully not replaced. Thanks for all your help guys.
     
    Last edited: Oct 16, 2011
  9. cuprastu

    cuprastu Member

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    Sep 25, 2009
    Location:
    Herts
    Car:
    W202 230K Sport
    Another vote for the maf sensor, my car wouldn't go above 80, nor accelerate from a standing start very well, cleaned maf and everything back to normal, in fact the idle was smoother after cleaning.
     
  10. BlackC55

    BlackC55 Authorised Forum Sponsor Authorised Forum Sponsor

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    Your best bet is to get it plugged in first. I take it its a diesel? If it is I doubt a MAF fault as they are fairly relaible.

    Inlet port shut off is my guess.
     

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