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1.9tdi sport poor mpg maf ????

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by rawtor51, Mar 30, 2012.

  1. rawtor51
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    rawtor51 Active Member

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    Guys,

    looking for advice here,my car returns roughly 500 miles to an £80 tank of diesel, its a non Quattro.

    Now the display2 shows an average of 35.9 mpg ive worked it out at 33.8 mpg.

    It heats up fine to 90 Deg C and stays there, heating is fine and no problems on the coolant side that i know of.

    Worth changing the MAF i can have a new Bosch one for 83.74 + vat.

    Its had new air & diesel filters and an oil change recently which didnt change anything.

    Thanks in Advance.
    #1
  2. mattyboyc
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    mattyboyc Active Member

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    Mine was returning an average of 33 mpg for ages and to be honest I didn't think it was that bad but my t
    preture was always below 90, I did a full service, injector cleaner and fuel filter, changed the temperature sender and thermostat also changed the maf and done the egr delete mod and my last to fill ups I have averaged 43mpg, I am due to fill up tonight ( if the silly arse people haven't panic bought it all) so will see what I get then.
    #2
  3. BlackQuat
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    BlackQuat Well-Known Member

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    My god! Our A6 130 is returning 52mpg and I thought it was broken.
    Change the CTS and see how that goes.
    #3
  4. rawtor51
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    rawtor51 Active Member

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    Thanks guys, may give that a shot in the near future, gonna give it a good motorway run to see what figures that returns
    #4
  5. pauldazzle
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    pauldazzle Active Member

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    CTS is a very common failure. Just because your temp gauge is reading normally doesn't mean the CTS is ok as the the CTS has 2 outputs one to the gauge & one to the ECU. If the ECU side has gone down the ECU won't be fueling correctly. The only way to check the ECU is getting a correct reading from the CTS is with VCDS/VAGCOM. Usually if the MAF is faulty performance really suffers, & it feels like you haven't got any boost. It's safe to unplug the MAF & see if the car runs better with it unplugged, if that's the case the MAF is goosed.
    If you decide to replace the CTS or the MAF use only genuine VAG parts as aftermarket CTS's & MAF's are notoriously bad.
    #5
  6. rawtor51
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    rawtor51 Active Member

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    Cheers Paul,

    its not the maf then , i unplugged it yesterday and it run like a bag of nails, plugged back in and it run fine again.

    done two seperate 10mile trips today both returning 39-40 mpg on the computer on a mixture of roads, not really any stop start either.
    #6
  7. pauldazzle
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    pauldazzle Active Member

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    Thats strange it shouldn't run badly with the MAF unplugged as if the ECU isn't getting a signal from the MAF it reverts to a set of default values.
    #7
  8. rawtor51
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    rawtor51 Active Member

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    Yeah no boost no power, ran a bit like it would if it was in limp mode
    #8
  9. pauldazzle
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    pauldazzle Active Member

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    You really need to get it hooked up to VCDS/VAGCOM & have a look at whats going on.
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  10. BlackQuat
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    BlackQuat Well-Known Member

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    Coudl well be the map sensor.
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  11. BuckleyTDI
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    BuckleyTDI Member

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    I've got a 130 sport tdi and it returns between 49-54 depending on driving never seen below 44 when hammering it either.

    James
    #11
  12. rawtor51
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    rawtor51 Active Member

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    Dunno guys out for another wee run today 18 miles, Country twisty hilly roads sitting around 65+ returning 47mpg on the computer, Is this all in my head or what, The car has been on vagcom a few times and never shown up any faults and its been logged on a run too, albiet not for a couple of months.

    Problem is i can jump into my non PD MK4 Golf and easily get 55mpg.
    #12
  13. stu_m
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    stu_m Active Member

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    Unplugging the MAF does not make it run default values it will put the car in to limp home mode this is not a good way to test them as it throws an error that will now be stored until its cleared

    A MAF needs checking with vag com
    #13
  14. pauldazzle
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    pauldazzle Active Member

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    Yep you're right Stu. I just tried it on my car & it went into limp. Strange as on VW's it doesn't, & on my old 2000 A3 1.8T Quattro it ran fine without the MAF plugged in.
    #14
  15. rawtor51
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    rawtor51 Active Member

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    Does on my mk4
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