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Possible faulty N75, how do I diagnose?

Discussion in 'A3/S3 Forum (8L Chassis)' started by Westy, Feb 9, 2010.

  1. Westy
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    Westy Double Dark Side! Diesel & 8P

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    I have no errors in VCDS but my car has been doing some strange things boost wise recently!

    Firstly I have had a strange fluttering noise since I first bought the car and it only does it when the engine is cold then it goes away when warm. And secondly my turbo has been getting louder as if the boost has been turned up and its spooling faster than normal!

    Is there any real way to diagnose the N75 valve? I seem to remember reading something about being able to log the N75 in VCDS and be able to see when its working?

    Any help appreciated guys.
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  2. s3dave
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    s3dave TFSI Hybrid

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    not sure how to check but ive got a liquid guage that can monitor the n75 and it bounces all over the place so i wonder if mine is fooked too
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  3. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Block 114 shows N75 duty cycle I think, will hit 90 odd percent while controlling initial onset of boost then settle... if its working ok it will stay more or less at the same figure after initial spike...

    <tuffty/>
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  4. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Cheers tuffty I'll give this a wirl.
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  5. badger5
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    badger5 RIP S3dave Site Sponsor

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    block 118 shows n75 duty cycle and actual boost, so combined with 115 block you can see it go to 95% initially to provoke spool then wind back to achive the requested boost
    in main engine setting, you can also exercise the solenoids including the n75 one (click click)

    only way to confirm if yours is on the fritz is swapping it for a known working one and seeing if there's a difference (what I do)
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  6. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    What he said :)

    <tuffty/>
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  7. Westy
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    Westy Double Dark Side! Diesel & 8P

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    You talk a good game mate:icon_thumright:
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