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boost gauge turbo flutter

V8Sam Feb 20, 2018

  1. V8Sam

    V8Sam Registered User

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    hello guys,

    done a bit of searching around and im not sure if its boost surge or flutter?

    so i thought id start a fresh.

    recently the car had an airtec intercooler fitted, as it turns out the battery was leaking over one of the older intercoolers causing a hole in it hence the boost leak. see previous posts.

    how ever, ever since fitting it, as the car builds up boost as normal the gauge needle can be seen heading up to 20 psi (which it normally boost at) but then once its there it flutters up and down incredibly so the needle is just a blur hence the 'flutter' term im using.

    you can hear it dumping at the equivalent rate of needle flutter, whilst this is happening the car really holds back on power.

    occasionally it boosts up fine and it runs perfectly. infact it runs very well, and very powerful.

    so, here is the question.

    whats do you think could be causing this?

    (unfortunately i cant do any logs as my laptop only runs whilst on mains power)

    also, is this bad for the car? (silly question maybe?) obviously trying to stay off boost as much as possible, and that seems fine driving round town, but the car is needed. so no real choice.
     
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  3. Stuart B

    Stuart B Registered User

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    DV Flutter - its usually a faulty Diverter Valve
     
  4. V8Sam

    V8Sam Registered User

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    faulty diverter valve? or the pipes that are to it? or both you think?

    i think its a forge type one.

    will try and take it out and plug it up see if it improves.
     
  5. GeorgieS3

    GeorgieS3 Registered User

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    I would replace with the oem valve mate, I had this exact same problem.
     
    andrew_wright likes this.
  6. V8Sam

    V8Sam Registered User

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    can a oem one fit in badger 5 tip?
     
  7. Stuart B

    Stuart B Registered User

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    yes of course, Bill virtually demands we all use OEM types :)

    maybe the spring is broken in your Forge DV don't they need servicing every year?
     
  8. V8Sam

    V8Sam Registered User

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    not sure?

    might have a spare spring somewhere though now you reminded me.

    ill look in the morning
     
  9. Stuart B

    Stuart B Registered User

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    You need silicon grease too and sometimes a piston if I remember rightly, but as others said just get a 710n or a 710p OEM DV. About £30 and will last for 10 years. The service kits are the same price.
     
  10. SHUk

    SHUk Once Bitten Forever Smitten =]

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    Try swooping the n75
     
  11. V8Sam

    V8Sam Registered User

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    Don’t have a spare n75.

    Will try one of my forge Dv off my b5 s4 to see if that cures it.

    If so I’ll go grab a oem one
     
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  13. Vishal Tween

    Vishal Tween Registered User

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    I had a forge DV fitted to my K03 MK5 gti running stage 2+. Useless thing. When it was failing the car topped out at 155bhp on the dyno. The curve double dipped!

    Swapped to Rev G and the car run sweet as a nut!
     
  14. nobbybonez

    nobbybonez Registered User

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    same, had a forge one fluttering and changed for oem, all sorted.
     
  15. Alex C

    Alex C Well-Known Member VCDS Map User

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    the boost gauge needle 'flutters' between what and what? 0psi to 20psi? 15psi? to 25psi?
    has the DV valve been installed the wrong way around? some people like to do this...
    does it still have the N249 valve?

    don't take the DV out and plug it up - that'll damage the turbo
     
  16. V8Sam

    V8Sam Registered User

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    Between 18-22 ish.

    Dv hasn’t been moved at all.

    Why would you want to install it the wrong way round?

    Infact how can you even install it wrong way round?
     
    SamHendry likes this.
  17. Alex C

    Alex C Well-Known Member VCDS Map User

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  18. desertstorm

    desertstorm Moderator Staff Member Moderator VCDS Map User

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    Is the turbo surging. If the intercooler has much better flow than the old one it may be allowing the turbo to surge. Does it start producing boost any sooner than before ?
     
  19. V8Sam

    V8Sam Registered User

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    Nope

    Runs as normal
    Untill boost is on

    Then it flutters

    If you are very gentle with the power it holds it to full boost with no problems.

    But 8/10 times it flutters and the power stutters with it

    Like I said will swap my b5s4 dv over at weekend if it stops I’ll get an oem one and keep you updated
     
  20. SHUk

    SHUk Once Bitten Forever Smitten =]

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    N75 valve
     
  21. V8Sam

    V8Sam Registered User

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    how would the n75 cause the stuttering?

    also whats the benifit/point of running a dv in reverse?:blink:
     
  22. Stuart B

    Stuart B Registered User

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    Unplug the N75 and see if it still stutters, it will be low boost but might help highlight the area.

    I think mostly myths and old wives tails, although I thought I could see some logic in it, being the pressure from the charge pipe is being diverted to the TIP, the flat faced bottom of the DV is facing that pressure rather than the side of the valve maybe the charge pipe pressure will open it quicker? Some people said it makes a nicer sound.
     
  23. SHUk

    SHUk Once Bitten Forever Smitten =]

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    N75 controls boost being the boost solenoid
     
  24. V8Sam

    V8Sam Registered User

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    little update on this.

    changed dv over for a known working forge one, that came off my s4 same issue.

    any other ideas floating about?
     
    Last edited: Mar 27, 2018
  25. superkarl

    superkarl MAN OF STEEL

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    Sounds like surge to me
     
  26. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow... Staff Member Moderator

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    If it's surge and not compressor stall then changing a dv will not help

    <tuffty/>
     
  27. V8Sam

    V8Sam Registered User

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    so, are the symptoms of boost surge any different to what was mentioned? bearing in mind it only happens when on boost and not when letting off. which i would assume is when compressor stalling is normally heard.

    how can you go about rectifying this? what would cause it to happen? just a new intercooler being fitted enough?
     
    Last edited: Mar 27, 2018
  28. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow... Staff Member Moderator

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    Fluttering under boost is generally surge.. . Fitting a fmic shouldn't cause it directly but it's plausible the increased flow capability could allow the engine to generate more airflow sooner and create surge

    It maybe that your map needs a tweak to sort boost out to prevent surge

    <tuffty/>
     
  29. V8Sam

    V8Sam Registered User

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    pretty much the conclusion we came to then.

    not much info on the map its running as its was done a while ago. and by a previous owner.
     
  30. Stuart B

    Stuart B Registered User

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    I would try to change the N75 you can pick up a second hand one for a few quid.
     
  31. superkarl

    superkarl MAN OF STEEL

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    There’s your problem
     
  32. V8Sam

    V8Sam Registered User

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    but never used to play up like this, since fitting the FMIC it has. so map tweek is looking like the option to go down.
     

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