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S3 only boosting to 5 psi

Rice Oct 6, 2013

  1. Rice

    Rice Active Member

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    Was out enjoying the nice weather earlier when my car started playing up, engine is running fine, so smoke, turbo sounds fine and boosts as it should, but stops boosting at 5 psi, when it usually boosts to around 20. I'm not that clued up with turbos, so I'm not sure what things to check? There's no warning lights on, all the hoses I can see look fine (would have to take the bumper off to fully check them all for leaks).

    Suggestions please :(. Ta
     
  2. Dani_B19

    Dani_B19 Audi-sports own special child.

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    You scanned for fault codes? Could be a faulty n75 and the cars just running on actuator pressure.
     
  3. Broken Byzan

    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User quattro Audi A4

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    Limp mode, it needs scannig for codes.
     
  4. Westy

    Westy Well-Known Member

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    Sounds like you've triggered limp mode which is where you're running on actuator pressure to protect the engine. Normally it will return to normal once the car has been turned off and back on again but there will be an underlying issue as to why it's hit limp mode. You'll need it scanned to figure out what though.
     
  5. Rice

    Rice Active Member

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    Ok I'll try get it scanned asap, thanks for the help :).
     
  6. Rice

    Rice Active Member

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    I don't know if this could've caused it, but it's got an n249 bypass, which I secured with cable ties behind the hardpipe to keep it out the way, the cable ties have melted, and when I pulled over to look it was sat on the manifold, so it has melted a bit...
     
  7. Westy

    Westy Well-Known Member

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    There's your problem....
     
  8. Rice

    Rice Active Member

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    Ah! Can I unplug it or will it not like it?
     
  9. Westy

    Westy Well-Known Member

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    Sorry I think I've got the wrong end of the stick. What has melted? The N249 valve/wiring or the hose you've used from DV to inlet manifold?

    Get it scanned. It might have thrown a wobbly because it thinks the N249 valve is shagged. When you do the bypass you should leave the valve electronically plugged in.
     
  10. Rice

    Rice Active Member

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    The n249, the wiring is ok, just. Ill try get it scanned tomorrow.
     
  11. badger5

    badger5 www.badger5.co.uk Site Sponsor

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    n249 shorted wiring? blown fuse, lost 12v so n75 has no power now...
    check your fuses and repair your damaged wiring and place it somewhere cooler next time
     
    Westy likes this.
  12. Rice

    Rice Active Member

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    Ah ok, thanks bud. Can I put a resistor in there to fool it into thinking its an n249? Cheaper than buying a new n249 if mine is buggered.
     
  13. badger5

    badger5 www.badger5.co.uk Site Sponsor

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    yes
     
  14. Rice

    Rice Active Member

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    ​Changed the fuse, taped up the wires (temp fix), didn't initially think they were damaged but they are. Going to put a resistor in as soon as I send off for one, as the plug and n249 are a bit melted.&nbsp;<br><br>Thanks for the help. Saved me a journey to get it plugged in ​
     
  15. boost-addict

    boost-addict Well-Known Member

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    why dont you buy a generic lead and download vcds lite, least you can read and clear most codes. its all i do and i have made do for the last year
     
  16. Rice

    Rice Active Member

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    I've been thinking about getting it but I wasn't sure where from. I guess I just need a USB to obd2 lead, and download vcds from a torrent site? Or can you get it free legally if its a lite version?
     
  17. boost-addict

    boost-addict Well-Known Member

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    yes vcds lite is a freeware download direct from rostech.

    i paid £8 for the lead

    i wish i had full vcds but to be fair its not bothered me too much,

    yes full vagcom would be wonderfull, but dont just dont do enough to warrant the price. im going to regester my liite version costs £60
    if and when i can afford to go big turbo i will defently buy the full version from ebay, so i can log fuel and boost etc

    and fyi you wouldnt even find it on torrents. and the generic lead wont work with the full version any how, the coding and software licence is within the brain of the hex lead.
     
  18. Rice

    Rice Active Member

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    Thanks for the info :)
     
  19. boost-addict

    boost-addict Well-Known Member

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    thats ok, a generic lead would tell you the code for your problem with no doubt,

    my brothers a3 was only boosting 5psi had a broken wire on the n75 valve.
    bought the car dirt cheap because of this i scanned it before he bought the car (with unregistered vcds lite) and the code stated broken wore or faulty n75 valve, as it said n75 valve short to ground

    so bought the car, fixed the wire, boosting 12psi. not had a issue since, altho he could do with a proper plug on there! rather then speaker terminals on the end of the prongs!
     
  20. Sidey

    Sidey Active Member

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    What Fuse was it that popped sir?
     
  21. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow... Staff Member Moderator Audi S3

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    There is info on getting a lead and VCDS lite plus links on looking up fault codes and how to log stuff here:
    http://www.audi-sport.net/vb/a3-s3-...-help-please-read-before-posting-updated.html

    This thread (and others) is in the FAQ's sticky...

    The full version of VCDS requires a genuine lead from RossTech and has a software dongle built it to allow the software to work... there are cheaper copies suggesting they are genuine leads with full versions of the software available for very little money (30-40 quid iirc) but... these are NOT genuine and Rosstech keeps on top of these by building checks into the software that stop it from working after a while...

    Get the lite version and if you need more then register it and it works as per the full version but is locked to one computer... full version can be used on any computer you have as its tied to the lead not the software

    <tuffty/>
     

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