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Maf seeing turbulent air, any idea on causes?

Discussion in 'A3/S3 Forum (8L Chassis)' started by slowcoach3, Sep 28, 2013.

  1. slowcoach3
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    slowcoach3 Active Member

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    [Sep 28, 2013]
    I've been doing some research and can't find much in the way of information, so wondered if anyone has any experience or knowledge on what causes a maf to see turbulent air? So far I've changed the maf as this needed doing anyway, swapped cone filters around, tried a short run wth no filter, changed the maf plug all to no avail. Both mafs were genuine bosch ones and have always been correctly supported by a heat shield on the end of my b5 TIP. Does anybody have any ideas?
    Cheers
    #1
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  3. jojo
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    jojo Looking for Boost! Staff Member Moderator

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    [Sep 28, 2013]
    How do you see/measure turbulent air going through the MAF ?!
    #2
  4. jimmcgee
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    jimmcgee Member

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    [Sep 28, 2013]
    X 2 :think:
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  5. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Sep 28, 2013]
    If the MAF tube is screened and has a straightener then it shouldn't see turbulent air... has seen idle and part throttle issues with de-screened MAFs before and even though it shows more airflow it actually makes less power

    <tuffty/>
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  6. slowcoach3
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    slowcoach3 Active Member

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    [Sep 28, 2013]
    When you log airflow on vcds, when the rpm is the same normally aaround 4k in 4th for example and you look at throttle position-always on light part throttle- and rpm whilst the throttle and rpm is exactly the same the maf readings are all over the place! Sorry if that's a convulted answer! When this turbulence occurs it shows itself as a pulsing which is felt in the cabin as it feels like it rocks the engine
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  7. slowcoach3
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    slowcoach3 Active Member

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    [Sep 28, 2013]
    The screen ia intact and I believe the maf is all in the correct position, sounds dumb but what do you mean by straightener?
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  8. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Sep 28, 2013]
    The plastic matrix thats typically covering the mesh... flow straightener...

    [​IMG]

    [​IMG]

    <tuffty/>
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  9. slowcoach3
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    slowcoach3 Active Member

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    [Sep 28, 2013]
    Thanks tuffty, should have realised lol Yup all is present and correct as bosch intended. Bloody car.
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  10. jimmcgee
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    jimmcgee Member

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    [Sep 29, 2013]
    #9
  11. slowcoach3
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    slowcoach3 Active Member

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    [Sep 29, 2013]
    Thanks dude, I appreciate that, I have given that a bash but I have tried pretty much everything, different brand new bosch mafs, filters no filters etc but it still persists. Weirdly its something that appeared overnight one day not there then bang. Doing my head in. Cars 100% fine on WOT though
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  12. jimmcgee
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    jimmcgee Member

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    [Sep 29, 2013]
    no problem lol , you have me wondering now , so going to log maf v rev on my torque app that i use every time in the car :thumbsup:
    #11
  13. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Sep 29, 2013]
    perhaps lambda playing silly buggers
    narrow band on yours yea?

    try disconnecting it and seeing how it fares
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  14. slowcoach3
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    slowcoach3 Active Member

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    [Sep 29, 2013]
    It is narrowband yes, disconnect the lambda? I'll give it a shot :) I'm going to be up with Phil tomorrow so I might bring something to bribe you with and try and pick your brains for a minute or two...
    #13
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  15. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Sep 29, 2013]
    You could try a velocity stack on the end of the MAF. Most factory installations have a velocity stack, and they're often binned when you fit a cone filter.

    That said, i cant see why it could just appear randomly one day. Might make sense if it appeared after you'd fitted the cone.
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  16. slowcoach3
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    slowcoach3 Active Member

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    [Sep 29, 2013]
    As you say it's random and that's what's annoying me! If something had been changed I would go back over everything but it doesn't seem to be that easy!
    #15

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