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ko3S boost leak-HELP, seriously, I've had enough

Discussion in 'A3/S3 Forum (8L Chassis)' started by Prawn, Feb 18, 2008.

  1. Prawn
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    Prawn My other car is a MINI!!!!

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    Hi guys, I need help.

    DESPERATELY.
    I've recently done a ko3S conversion on my AGU, I like to think I've done a fairly good job of it too.

    The problem is, ever since fitting my FMIC from tuner-stop.com, I have had boost leak problems.

    These were not apparent before mapping, but were very clear after it was mapped.

    Around 12-14psi, I get a quiet whine beginning, then around 15psi, this turns into a full on scream sounding like a ghost train! the noise gets more and more high pitched as boost builds, to a max of 18psi spike, and holds around 15psi, with the scream constant.

    The car was mapped to spike 22psi, and hold 20psi. Which it did, for around 30 minutes after I picked it up from Storm.

    It also did not make any screaming noise. There was obviously a slight turbo whislte at low throttle, and there still is, but nothing sounds like this bastard!

    So, to fix the problem, I have done the following:

    Tighten all T-bar clamps on the 3 ply silicon couplers it came with Still leaks
    Replace cheap silicon with very thick tight fitting 4 ply from Siliconhoses.com Still leaks
    Replace T-bar clamps with JCS HI-Torque stainless worm drive clamps Still leaks

    Add mikalor clamps on every joint, so its now double clamped Still leaks
    Add an RTV silicon sealant to every joint Still leaks

    Rebuild forge 007P, run it both ways, no difference Still leaks
    Run new N75 hose, with sealant at both ends Still leaks

    I give up.

    I am running a brand new forge cold side kit, with the DV right near the throttle body
    the ko3S has done around 60k miles, and seems to be in great condition with no play in the shaft. the wastegate hasn't been adjusted since comming off a TT.
    I have had the core pressure tested this evening, and it showed no leaks at 1bar at all. I have asked them to test it at 2bar, which they will do in the morning, although they do not think it will leak at all.

    really guys, help me! I have NO idea what can be the cause of the leak now, I have done everything I can possibly think of, short of selling the car and buying something jap and chavvy that will at least work.


    Any suggestions what the problem could be? To me, a noise that was not previously there, and a drop in boost, coupled with it using LOTS of fuel, and back firing very loudly on down shifts, can only suggest a boost leak.

    but where from????
    #1
  2. jesters3
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    jesters3 Active Member

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    Have you got a VAG.COM error at present;this may help single out the location. Currently have a 17705 boost leak on my BAM S3, after checking all the hoses I have found a split hidden between two hoses - you couldn't see the split until you pulled them appart - near the oil reservoir; have ordered the part and waiting to see if this clears it as like you i have checked all visible hoses and the like. Failing that Stewart mentioned that under the manifold are more hoses that are prone to splitting (esp in Cupra 1.8T) so I'll be looking at them next.
    #2
  3. HTC
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    HTC Active Member

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    I don't mean to unduly worry you, but a whine may not be a boost leak.

    I've heard noisy turbos that have ingested a foreign body into the compressor sound like you describe. Seeing that you've done everything to search for leaks I would at least pull the TIP from the inlet of the turbo to check for a bent blade.

    Or eliminate the new intercooler. Either plumb in the old one or bypass it all together and perform one run to see if the sound disapears.
    #3
  4. golf
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    golf ***** rent boy

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    Make one of those home made boost leak detectors to find the culprit.

    A4mods.com has a writeup.
    #4
  5. pat@forge
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    pat@forge New Member

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    I'll second the boost leak tester, traditional vacuum leak tests do not suffice on turbo cars as there can be leaks that only appear when the charge piping is pressurized.
    #5
  6. Jimbo.King
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    Jimbo.King Member

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    Hi, have you found anything to sort the problem out yet Prawn, im having the same problem with my A4.

    Mines Mapped to hold at 20/21psi and it dropped to 15/16psi along with a louder Turbo whistle that wasn’t as noticeable as before as it was more of a rush of air suction from the induction
    It also seems a little lazy to make the boost, before it came in like an on off switch.

    I’ve had all the induction / boost pipes off, done a pressure test to 22psi with no leaks, removed the N75 and cleaned it out, cleaned Maf + Map sensors with no luck, cleaned the forge diverter valve and re-greased, cleaned air cleaner.

    The turbo has some very slight up / down play and some in and out play in the shaft with no damage to the blades or housing.

    You seem to get the effect of the turbo trying to make the boost with the loud whistle but the wastegate is slightly opening bleeding some off.

    Im going to replace the N75 next and failing that remove the cat to see what’s going on that side of the turbo.

    Any other help would be very appreciated
    #6
  7. A3_Turbo
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    A3_Turbo Swaying towards IHI....

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    Spoke to Prawn the other day on the phone,

    I believe the problem was down to the turbo and he spicked up a replacement K03S.

    Im sure he'll be along soon to clarify...

    Jason
    #7
  8. Prawn
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    Prawn My other car is a MINI!!!!

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    I found out what my problem was, the turbo was dead!

    I had it checked out on a few different rolling roads, and there is no boost leak at all. The sound i hear is the turbo whinning as it comes on boost, as it looks like the thrust bearing has given up.

    Mine still spikes 22psi, but it wont hold it at all.
    As a result, its currently whinning terribly, and
    making 202hp and 240lbft, so a fair bit down on where it should be :(

    http://www.jkm.org.uk/performance/GallerySCN010308.htm

    mines the only audi on that page, thats from the SCN RR day yesterday.

    On the bright side, I picked up a genuine 26000 mile old ko3S from an 04 ibiza cupra yesterday, for the lovely price of £100!

    I'll get that fitted, and get it dyno'd again, and let you know the results
    #8
  9. HTC
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    HTC Active Member

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    So you aren't going for the hybrid now I assume?

    Good score picking up that k03s for a ton.
    #9
  10. simch
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    simch Active Member

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    I think your turbo could have been goosed due to the set up you have there.
    Any "screeching" from a turbo is not good. The fact it started 30 minutes after pickiung up your car suggests that the mapping (either process of or the actual map) are too agressive for your turbo.
    It could also be a n249 valve or wastegate problem that caused some over boosting whihc goosed your bearings.

    But i would be wary with the new turbo also, it would be a shame if there is some issue that will destory that one too, if only because they are a right pain to fit!

    My AGU K03s has been on now for 4 years and 60k miles car now done 125k. So it should be a reliable conversion if done carefully.
    #10
  11. Dave_Bayern
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    Dave_Bayern Slipping at 3.5Krpm

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    I also have the same setup as Prawn, K03s, but my map is slightly less agressive than his (boosts to 17psi) and mines been fine with no issues or noises whatsoever for 6K miles so far.

    Same mapping company though, so it could be hardware and software related the problems he is having.
    #11
  12. Jimbo.King
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    Jimbo.King Member

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    Cheers for the replys guys, ive just got it sorted, Heres what i found when i took the downpipe off:-

    [​IMG]
    [​IMG]

    The cat has decided to break up and block the hole that leads to the downpipe, it must have been back feeding into the turbo making it sound different and causing the lack of power.

    No wonder the turbo and manifold glowed cherry red after a short run !!

    Back to normal running and holding at 20/21psi (k03) and its never gone so well, even after a good hard drive the turbo only glows slightly now so im well happy. :rockwoot:
    #12
  13. RSTuning
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    RSTuning New Member

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    I assume you have fitted a nice new cat then Jim ;)
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  14. Jimbo.King
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    Jimbo.King Member

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    LOL its a modified one :p
    #14
  15. RSTuning
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    RSTuning New Member

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    0 Cell sports cat yeah?
    #15
  16. AudiSport
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    AudiSport Member

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    What is a 0 cell cat - and how much?
    #16
  17. Prawn
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    Prawn My other car is a MINI!!!!

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    is that a joke? I do hope so :)

    If not, then I can tell you.

    a 0 cell cat is a cat with no cells, so it converts nothing.

    Its basicly a straight bit of pipe, or a cat with no middle to it!
    #17
  18. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    :laugh::laugh::laugh:
    #18
  19. HTC
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    HTC Active Member

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    Or a cat that doesn't sell very well?
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