1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

1.8T AUM Throttle closing under power?

Discussion in 'A3/S3 Forum (8L Chassis)' started by Craig1.8t, Sep 12, 2013.

  1. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    First off I have no logs as of yet, these will come in the next few days, all I have is a description of whats happening.

    On full throttle the boost builds up to 19-21psi and just after this the throttle body closes, opens, closes, opens, closes, opens and so on until red line, does this in every gear its not violent or jerky its pretty smooth. its not closing fully (Last log I did shown a sign of this but since then I haven't done any other logs. On previous log I saw 30 odd percent when I was giving it WOT.

    So in a nut shell, what could be telling the throttle body to back off?

    If I am on honest I must say the actuator isn't in its ideal position, the rod has to be pulled over to waste gate arm, this makes the actuator a bit harder to control wastegate arm as it only wants to open at 8psi but with rod not connected it opens at 5psi so I know the preload is fine. I'm sure this could be my problem, but I thought I would ask if there is anything else that could be causing me this problem?

    Thanks.
    #1
  2. Broken Byzan
    Online

    Broken Byzan Photographic Moderator Staff Member Moderator

    Joined:
    Apr 26, 2004
    Messages:
    12,568
    Likes Received:
    267
    mods? what map is it? Is the map suited to the mods? Seems like you have alarge turbo perhaps?

    Not really enough info to make a call
    #2
  3. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    Sorry, it has de-cat I have replaced turbo and fitted a ko3s/82 I believe? from the polo gti bjx engine. Is this not the same turbo? stage 2 map (not custom) no other mods apart from a panel filter.
    #3
  4. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    Also replaced front lambda, throttle body, n75, maf, gave it a full service checked timing
    #4
  5. beachbuggy
    Offline

    beachbuggy Well-Known Member

    Joined:
    Jan 27, 2010
    Messages:
    1,756
    Likes Received:
    139
    Throttle cut... Over boost so the ecu closes the throttle..
    #5
  6. Broken Byzan
    Online

    Broken Byzan Photographic Moderator Staff Member Moderator

    Joined:
    Apr 26, 2004
    Messages:
    12,568
    Likes Received:
    267
    I'd say it's reacting to the turbo. You need to get it mapped to match the turbo. Need to log boost and load request at a min to catch what's over reaching it's mapped limit
    #6
  7. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    Thanks, so as I described the actuator being difficult to move due to the rod having to be forced over to slot into the WG arm, this could cause the problem?
    #7
  8. Broken Byzan
    Online

    Broken Byzan Photographic Moderator Staff Member Moderator

    Joined:
    Apr 26, 2004
    Messages:
    12,568
    Likes Received:
    267
    not likely, it will make boost control difficult, however logs will show it not reacting as expected
    #8
  9. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    I will get some logs then and let you know, just want to add the power delivery from full boost doesn't come until around 3,500-4000rpm. Thats like td05 lag lol from evo lol.
    #9
  10. Broken Byzan
    Online

    Broken Byzan Photographic Moderator Staff Member Moderator

    Joined:
    Apr 26, 2004
    Messages:
    12,568
    Likes Received:
    267
    hae you had a smoke test done?

    If the actuator was holding closed due to rubbibg i'd expect it to boost early not late, I guess it could be holding open... What's it like with n75 electircally disconnected
    #10
  11. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    Replaced all vac pipes under inlet manifold all clips fitted etc, no leaks anywhere on the car boost pipes or vac pipes. Sometimes hits limp mode and when it does this, its 5 psi max boost, am I right in thinking unplugging n75 is same as limp mode?

    I get SAI incorrect flow fault code I'm guessing this hasn't anything to do with this though.
    #11
  12. badger5
    Offline

    badger5 RIP S3dave Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,263
    Likes Received:
    668
    ecu intervention

    map not matching hardware my guess
    #12
  13. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    Hmmm what to do. How can I prove this Bill? If I put original file in and get no boost cut will this be enough evidence to almost guarantee its the map? Any suggestions to try prove its the map would be much appreciated as it would cost me around £500 to come to you and I can't justify spending that much dollar for in case it doesn't solve the issue.

    Thanks in advance
    #13
  14. badger5
    Offline

    badger5 RIP S3dave Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,263
    Likes Received:
    668
    if you see the ecu intervene and close the throttle on your current map, and flash another map onto it and it does'nt... then there is a high likelyhood the first maps not suitable for the hardware.

    I dont recall your spec however..
    #14
  15. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    Spec is std apart from decat and panel filter, Turbo is std from polo gti BJX engine ko3/82 which I believe is the same as an aum ko3s, is this right? All I have is std map, but std boost pressure is lower than mapped boost pressure so it may lead me down the wrong path. Getting another mapped file 'to test' might prove a little tricky. I will see what I can do. Thanks
    #15
  16. badger5
    Offline

    badger5 RIP S3dave Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,263
    Likes Received:
    668
    who's "map" is on it now?

    flash to stock will confirm its working as expected - the hardware should'nt be different.. k03s for another k03s, unless its actuator is much stiffer than 5psi

    got any logs yet dude?
    #16
  17. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    I'll get you some logs Bill. I will send you them through Facebook, I won't be like last time I promise I was a pain last time coming to think of it, lol. (A mans just desperate :( lol) Actuator cracks off at 5psi that is all I can pretty much say about how my actuator works. I want to change my actuator but not looking forward to removing manifold, can it all be done from up top? Cheers
    #17
  18. badger5
    Offline

    badger5 RIP S3dave Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,263
    Likes Received:
    668
    if you remove mani and can access the oil/coolant banjo bolt which traps it yes
    #18
  19. Craig1.8t
    Offline

    Craig1.8t Member

    Joined:
    Dec 7, 2011
    Messages:
    108
    Likes Received:
    6
    Thanks mate, I will change it for my peace of mind so I know it's right, I will take it from there. Will report back with any news. Thanks
    #19

Share This Page