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S3: Surging on Part Throttle. N249?

Discussion in 'A3/S3 Forum (8L Chassis)' started by AL_B, Apr 4, 2005.

  1. AL_B
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    AL_B Active Member

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    Hi guys,

    Having had my spark plugs changed, in the hope of fixing the hesitation (split-second loss of boost) that occurred at about 3800rpm. And it did seem to fix that problem.

    My car now has another problem....a surging or running-on feeling on part-throttle. It also seems to get confused in high-revs throttle-on-off-backon situations.

    My intial thoughts were, it has to be the DV, and it could still be that. But browsing the internet and talking to my dealer, seems to suggest it could be the N249 valve.

    Paul-S3 - I saw your post on tyresmoke about the N249. What caused you to think there was a problem? Was it surging?

    Anyone else experienced this and know the exact cause/solution?

    Cheers

    AL
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  2. Khufu
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    Khufu Active Member

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    I dont know if it helps but mine does it too occasionally when you take your foot off the throttle it seems to surge a bit and I dont have a turbo...
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  3. AL_B
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    AL_B Active Member

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    Cheers Khufu, but I think I may have found the cause of the problem.

    There could still be a problem with the N249 or DV, but I have found a hole in one of the tubes going into the N249. See pics...

    [​IMG]

    [​IMG]

    Got the idea to check this from Wak's site...

    http://www.wak-tt.com/warnings/n249pipe.htm

    (nice one Wak)


    AL
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  4. AL_B
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    AL_B Active Member

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    Hole is caused by the electrical connector rubbing against the tube over the period of years.

    How the "mechanic" did not spot this when the plugs were changed I do not know.

    AL
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  5. Khufu
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    Khufu Active Member

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    Glad you found out the cause. Let us know if repairing it rectifies your problem.
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  6. olekvi
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    olekvi Member

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    [ QUOTE ]
    Hi guys,

    Having had my spark plugs changed, in the hope of fixing the hesitation (split-second loss of boost) that occurred at about 3800rpm. And it did seem to fix that problem.


    [/ QUOTE ]

    I'm having a similiar problem with my car now; could you please describe how 'you felt it'? (full throttle, part throttle?)

    regards
    #6
  7. PaulRS3
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    PaulRS3 Active Member

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    "Paul-S3 - I saw your post on tyresmoke about the N249. What caused you to think there was a problem? Was it surging?"

    hi mate, ive never had a problem with this valve, i just posted a pic so people could see where it was located.

    common faults are its been unplugged, pipe popped off or a split like Waks site.

    the N249 controls the DV.


    N75 controls wastegate.
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  8. AL_B
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    AL_B Active Member

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    Cheers Paul.

    I temporarily put some insulation tape around the hole this morning and there has been an improvement. No hesitancey in on-off-backon throttle situations. There may still be a little surging, not sure.

    Still going to get the dealer to do a diagnostic, replace the pipe and possibly the N249.

    AL
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