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C240 low idle

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by bc100, Nov 8, 2018.

  1. bc100

    bc100 Senior Member

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    Your Mercedes:
    S203 C 240 estate 2001
    I have an slightly low idle on my 2001 C240 that occasionaly feels as though it might stall. Is this a simple adjustment?
     
  2. grahamcol

    grahamcol Senior Member

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    Your Mercedes:
    2001 SLK230, 2000 C280 V6
    My understanding is that the idle speed is controlled by the ECU and that it is fixed. However something's causing the low idle speed. Maybe the car needs a star diagnostic to help establish the cause.
    Good luck with it.
     
  3. alexanderfoti

    alexanderfoti MBO Forum Supporter Authorised Forum Supporter

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    Your Mercedes:
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    Could need a throttle body clean and adaption reset.
     
  4. OP
    bc100

    bc100 Senior Member

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    Reading further, some people have seen this behaviour linked with accelaration hesitancy which I also have from time to time. This could be due to a MAF sensor fault.
    Star would be good but I don't know a local garage that does just a star diagnostic. I have been going to Avantgarde but it is a long way for something that isn't too serious.
     
  5. alexanderfoti

    alexanderfoti MBO Forum Supporter Authorised Forum Supporter

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    Ah yes, if you also have drive ability issues, then I would suspect the MAF. If its not bugging you then maybe wait until you have a service due and go to Avantgarde?
     
  6. OP
    bc100

    bc100 Senior Member

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    Is it worth trying to clean it, assuming its dirty of course?
     
  7. AnthonyUK

    AnthonyUK Senior Member

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    Your Mercedes:
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    A simple check is to ensure the engine cover/filter housing is sitting correctly on the MAF. I had this once after changing the air filters.
     
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  8. OP
    bc100

    bc100 Senior Member

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    I'll have a quick look in the morning and report back. Thanks all for speedy replies.
     
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  9. LostKiwi

    LostKiwi Senior Member

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    Your Mercedes:
    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    Generally there is little point in trying to clean it.
     
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  10. Steve@Avantgarde

    Steve@Avantgarde Forum Supporter Authorised Forum Supporter

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    I too would suspect the MAF. Nothing to adjust on these engines, but not a lot that controls its running values other than the MAFs either.
     
  11. OP
    bc100

    bc100 Senior Member

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    So just buy a new MAF then? I'd pop up Steve, but as you know I'm a long way away unless I'm on my way to Bristol.
     
  12. Steve@Avantgarde

    Steve@Avantgarde Forum Supporter Authorised Forum Supporter

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    I would still STAR test it, otherwise its nothing more than a best guess. If you are going to replace the MAF, make sure it is a Bosch unit.
     

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