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8L S3 limp mode but no fault codes?

Discussion in 'A3/S3 Forum (8L Chassis)' started by Craig1.8t, Jan 24, 2012.

  1. Craig1.8t
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    Craig1.8t Member

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    Friend of mine has an Audi s3 1.8t and I've done a smoke test found pcv pipe split replaced that and it's still same. Clamped pipe to actuator and it boosts. Changed n75 made no difference. Any ideas?
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  2. Nilz
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    Nilz Defo worth the wait :)

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    What are the symptoms?
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  3. Craig1.8t
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    Craig1.8t Member

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    It feels like limp mode, that's best way to describe it. Smooth just no power.
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  4. Lewis583
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    Lewis583 Active Member

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    Done any logs? Tried unplugging the MAF?
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  5. Craig1.8t
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    Craig1.8t Member

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    Not done any logs, and can't do any till next week if I did. Maf is fairly new but tried unplugging it and still same. Pcv valve works as should too. As I said I made it run a lot better when a stopped the waste gate from opening, so must be related to that surely?
    Last edited: Jan 25, 2012
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  6. Steveo_A3_1.8t
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    Steveo_A3_1.8t Member

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    I read somewhere of a similar problem on an Ibiza, and it turned out the wiring to the N75 plug was faulty, maybe worth stripping back the trunking and checking it out.

    Steve
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  7. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    No, not really... the lack of boost is a symptom not a cause... all you have done is taken the ECU's control of boost and something I might say could lead to catastrophic engine failure so its not advised to fault find this way unless you are being very careful...

    Logging is the next step if you have no fault codes...

    As you have not given much info about the car at all are we to assume its mapped? what boost is it running currently? (actual boost not what you think it should run), what boost does it run with the N75 electrically disconnected? (that should also throw a fault code so don't forget to clear it)...

    Std S3's run to around 12psi normally, 3-5psi with N75 disconnected and typical up to 20/22psi mapped depending...

    <tuffty/>
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  8. Craig1.8t
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    Craig1.8t Member

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    Sorry. The car is fully standard. Brand new engine last year. According to measured values the boost matched specified. I put the pipe back as normal and stopped boosting once the boost came in.
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  9. quattros3
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    quattros3 New Member

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    Variable nozzle turbo. Sticking vanes!!
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  10. Alex C
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    Alex C Well-Known Member

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    not in a petrol motor, diesel maybe, but not a 1.8T. Petrol engines get too hot for a variable geometry turbo
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