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

Question - N75 open circuit fault

Discussion in 'A3/S3 Forum (8L Chassis)' started by Scullies, Oct 5, 2012.

  1. Scullies

    Scullies Well-Known Member

    Joined:
    Feb 9, 2012
    Messages:
    1,395
    Likes Received:
    413
    I have had some boost issues, no boost sometimes then full boost then half boost.
    Did a scan and found N75 open circuit.

    I took the N75 out and tested it will a compressor and 12v, when I apply the 12v the air gets diverted back towards the TIP, no voltage air is diverted to wastegate. There is also power at the N75 plug.
    Weird thing is its only seems to be a problem when things are hot underneath the bonnet.

    Would an ultrasonic clean do anything for it and some heat protection or relocation?

    Or is it in need of replacement?
     
  2. Google AdSense Guest Advertisement



    to hide this advert.
  3. <tuffty/>

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

    Joined:
    Sep 14, 2008
    Messages:
    17,999
    Likes Received:
    2,289
    Open circuit fault is electrical... sounds like you have a break in the wire somewhere... it happens more often than you think...

    <tuffty/>
     
  4. Scullies

    Scullies Well-Known Member

    Joined:
    Feb 9, 2012
    Messages:
    1,395
    Likes Received:
    413
    Bugger, guess I will be pulling wire over the weekend :(
     
  5. Westy

    Westy Double Dark Side! Diesel & 8P

    Joined:
    Dec 2, 2008
    Messages:
    17,362
    Likes Received:
    1,009
    Tam just had this issue on his mates Ibiza. There's a thread somewhere in the 8L section from about a week ago. He sorted the issue by replacing the wiring.
     
  6. Scullies

    Scullies Well-Known Member

    Joined:
    Feb 9, 2012
    Messages:
    1,395
    Likes Received:
    413
  7. Scullies

    Scullies Well-Known Member

    Joined:
    Feb 9, 2012
    Messages:
    1,395
    Likes Received:
    413
    So after replacing the wiring and N75 plug, it still playing up. So this time when it was hot and had thrown the fault, I tested the N75 for resistance. There was nothing across the 2 terminals, I let it cool down and tested it again. I got a reading of 30.4 Ohms. So I then relocated the N75 to behind the front left head light, went for a drive. It seemed to run for longer without throwing an error, then as soon as I tried to have a go with a Mk6 Gti, BOOM - no boost and the Gti left me as if I was looking for parking.

    So my next plan is to relocate the boost feed to the N75, currently the N75 gets its boost feed from the the original place. This is hot compressed air directly from the turbo.
    Would it affect anything N75 related if I moved the boost feed to after the FMIC and before the TB. I have already extended the return to TIP and wastegate lines when I relocated the N75.
     
  8. badger5

    badger5 www.badger5.co.uk
    Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    8,142
    Likes Received:
    1,097
    you just sound like you have a buggered n75
     
  9. Jezzas3s

    Jezzas3s New Member

    Joined:
    May 15, 2012
    Messages:
    12
    Likes Received:
    0
    I think i got a spare n75 valve.
     
  10. Scullies

    Scullies Well-Known Member

    Joined:
    Feb 9, 2012
    Messages:
    1,395
    Likes Received:
    413
    PM sent :thumbsup:

    So I relocated the boost feed to the N75, fitted a nipple to the intake pipe after the IC, N75 still having heart failure when it gets hot. So looks like a new one for me.
    However, with the N75 relocated, the car seems to pull so much better until it stops working. I cant see how the relocation would have any affect on the power, its probably one of those mind game things like when you change something the car feels so much better :wacko:
     

Share This Page