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MPG gone aweful suddenly.

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by BlackQuat, May 3, 2011.

  1. BlackQuat
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    BlackQuat Well-Known Member VCDS Map User

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    [May 3, 2011]
    The mpg on my 2.5 tdi has suddenly gone aweful. I used to constantly see 38mpg, 35 if i was a naughty boy occasionally.
    Recently, when filling up and working it out. It's always on 31mpg.
    MAF? Temp sensor?

    Any tests using vcds worth doing?
    #1
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  3. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    [May 3, 2011]
    I take it you've scanned it and no fault codes?
    #2
  4. BlackQuat
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    BlackQuat Well-Known Member VCDS Map User

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    [May 3, 2011]
    I've done a scan on the engine, only fault is an engine code James.
    I did notice theres a 4 degrees temp difference between engine and instrument temps. Does that sound normal?
    #3
  5. Avant4me
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    Avant4me The're Graphite not black!!

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    [May 3, 2011]
    4 degrees is about right, the gauge is never going to be accurate.
    #4
  6. audigeezA4
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    audigeezA4 Member

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    [May 4, 2011]
    i have already accepted that the mpg on mine is never gonna be much more than what i am getting now, with a mixture of motorway and town driving i get 30.91mpg working it out manually, however, the dis states 24.8mpg on the 2 setting- so clearly my dis is completely inaccurate, i have even calmed down with my driving style but alas no effect.
    #5
  7. BlackQuat
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    BlackQuat Well-Known Member VCDS Map User

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    [May 4, 2011]
    Really odd, as when I took it to FortWilliam, I got 45mpg. That's worked out at the pumps too.
    #6
  8. vinesh
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    vinesh Member

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    [May 4, 2011]
    Hi,

    Have you checked for boost leaks.

    Is yours a auto or manual?
    #7
  9. audigeezA4
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    audigeezA4 Member

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    [May 4, 2011]
    Blimey, 45 would be nice. I thought 30-35 was the norm anyway? I have only got 64k on the clock with fdsh, 53 plate,Manual so i thought i would get betta mpg than say a higher mileage. I recall someone saying cleaning the injectors, replacing air/fuel filters would help which i will get roubd to doing mine- one day.
    #8
  10. BlackQuat
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    BlackQuat Well-Known Member VCDS Map User

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    [May 4, 2011]
    Mines a manual.
    When I said the difference in temps. I meant on vcds. Logging into instruments and engine. The engine temps are different.
    #9
  11. silversurfer
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    silversurfer Member

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    [May 4, 2011]
    Mine mates Diesel BMW had a similar issue, and he's just had to get a new turbo as the oil pipe was blocked :)

    This also didn't show up on the diagnostics before hand.
    #10
  12. Jama665
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    Jama665 Member

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    [May 5, 2011]
    try some redex or similar. dirty injectors are not good for diesels mpg. easy to do and could sovle the issue.
    #11

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