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only 0.4bar boost?

Discussion in 'A4/S4 forum(B5 Chassis)' started by neilA4, Mar 12, 2010.

  1. neilA4
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    neilA4 Member

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    [Mar 12, 2010]
    Finally fitted boost gauge,

    I'm only making 0.4bar! It's a steady 0.4 bar, no spikes. Thought the car felt slow!

    Apart from a boost leak what could it be?

    Whats the easiest way to get to the actuator? just want to make sure the nuts havent come loose on the threadded bar?
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  3. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Mar 12, 2010]
    0.4bar is actuator pressure.

    Means the ECU's dropped into limp mode, or the N75 is faulty
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  4. neilA4
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    neilA4 Member

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    [Mar 14, 2010]
    I've checked for fault codes, only one is where i have disconnected the battery. Would the N75 give a fault code if bust?

    ta.
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  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Mar 14, 2010]
    Ye it did on ours when the wiring broke.

    But then if it was a mechanical failure you'd also get a fault code...

    When our turbo broke, it popped a "charge pressure limit not reached" code.
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  6. neilA4
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    neilA4 Member

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    [Apr 13, 2010]
    So far I have checked the inlet piping and swapped the n75. Now i'm only getting 0.3 bar !!!

    There is a slight rattle coming from the cat / wastegate area at certain revs whilst on throttle and off throttle, the actuator is in one peice so i'm thinking the penny valve is lodged in the cat? Also seemed a lot of play in the shaft when I had the inlet pipe off.

    I have a spare k03-029 exhaust housing but my turbo is a k03-005 so i'm guessing it will not be compatibale due to the larger exhaust wheel on the -029?

    Can you run a scroll sp51R on standard ECU? without any fuelling issues? This looks to be a good option at the minute as they are on ebay for $550 just need to bolt up to -029 exhaust housing, which I have spare!!

    http://cgi.ebay.com/ebaymotors/ws/e...0366860981&viewitem=&sspagename=STRK:MEWAX:IT

    Cheers
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  7. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Apr 14, 2010]
    Without a wastegate penny you'd struggle to see any more than 2 psi i wouldnt think.

    On ours (and a few others on here) when the penny came off, it didnt drop into the cat, it went the other way, inside the turbine housing, and blocked the entrance to the turbine, meaning the entire engine was breathing thru the wastegate hole.

    You could test it by removing the boost sense line on the actuator and blocking up the pipe, then very carefully seeing if it will make any more boost. bear in mind without the boost sense line the boost could easily climb to 20-30psi.
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  8. neilA4
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    neilA4 Member

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    [Apr 15, 2010]
    Just ran a code check

    VAG-COM Version: Release 409.1-S
    Control Module Part Number: 8D0 907 558 DA
    Component and/or Version: 1.8L R4/5VT MOTR HS D01
    Software Coding: 04201
    Work Shop Code: WSC 06325
    2 Faults Found:
    00575 - Intake Manifold Pressure
    11-10 - Control Limit Not Reached - Intermittent
    01262 - Shareware Version. To Decode all DTCs
    26-00 - Please Register/Activate

    At least it know's it's not boosting, will try your test tomorrow cheers
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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Apr 15, 2010]
    the "Control limit not reached" is what i was getting when the wastegate failed, however you also have 01262 which means theres a fault with the N75 valve.

    Unfortunately the shareware version you have isnt showing what is wrong with the N75 valve.

    Clear the codes and see if the N75 one comes back with a real description.
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  10. neilA4
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    neilA4 Member

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    [Apr 15, 2010]
    cleared codes and just sat there on idle-

    VAG-COM Version: Release 409.1-S
    Control Module Part Number: 8D0 907 558 DA
    Component and/or Version: 1.8L R4/5VT MOTR HS D01
    Software Coding: 04201
    Work Shop Code: WSC 06325
    1 Fault Found:
    01262 - Solenoid Valve for Boost Pressure Control (N75)
    26-00 - Output Open
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  11. neilA4
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    neilA4 Member

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    [Apr 15, 2010]
    :redface:Well, ive just plugged the n75 back in (oops)

    Been for a run and no fault codes now, may need a longer drive to register low boost not sure? Still only 0.3 bar max and rattle on/off throttle

    cheers.
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  12. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Apr 15, 2010]
    Ours popped the code the first time you gave it some throttle when the wastegate was dead. It was also seriously slow, even trying to hold 70 up motorway hills required mostly full throttle.

    It did rattle BEFORE the valve fell off, but once it failed the rattle stopped.
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  13. neilA4
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    neilA4 Member

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    [Apr 15, 2010]
    Well the car is not that slow, looks like something is wrong with the penny valve/actuator then. could be poorly adjusted actuator.
    The sp51r kit is tempting, just don't want to take my turbo off and find it's something simple to fix lol

    car has done 120,000 so turbo prob a bit tired anyway.

    Cheers
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  14. neilA4
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    neilA4 Member

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    [Apr 16, 2010]
    Well had another look, wastegate arm seems pretty stiff, if I hold it and rev the engine you can feel/hear the rattle is pretty bad!!!

    SP51R is on the way hopefully!! To bolt up to my pristine -029 housing.
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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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    [Apr 16, 2010]
    Ours only ever rattled on the overrun. Maybe the actuator isnt applying enough pressure to keep the gate shut?
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  16. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Apr 16, 2010]
    Also you will need to liberate your actuator for the Scroll as Sean doesn't supply them with the CHRA.

    Yes you can run the scroll on a normal ECU buy it won't be any faster than a working normal turbo.
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  17. neilA4
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    neilA4 Member

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    [Apr 16, 2010]
    I have a spare actuator.

    I'll be happy just to have a working turbo for a while lol
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  18. neilA4
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    neilA4 Member

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    [Apr 18, 2010]
    actually, I may put a forge one on there, should be able to get to the little screws to change the spring if I need to, just saves having to take the turbo off to piss around with actuator!!
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  19. neilA4
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    neilA4 Member

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    [Apr 30, 2010]
    SP51R K03-029 Turbo has arrived, All bolted together ready for the swap over tomorrow. Managed to get a forge actuator body off ebay for £13 then went to forge today (only live 15 min away) and got the internals for £45, so all together £58!! Had to cut off an old actuator and drill bracket to fit it. The threaded rod is JUST long enough for a couple of turns to preload actuator a bit, may get longer rod tomorrow not decided yet. Pics...

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    Last edited: Apr 30, 2010
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