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Jay A3 KO4 build

Discussion in 'A3/S3 Forum (8L Chassis)' started by Jay A3, Dec 8, 2011.

  1. stevegti2
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    stevegti2 Member

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    do you live in welling ? or park there on a often basis near the blockbuster and suzuki motorbikes because i see a car that looks alot like this all the time there lol

    steve
  2. Jay A3
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    Jay A3 come fly with me

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    Thanks Ben, you thinking day time or afterwork?
  3. Jay A3
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    Jay A3 come fly with me

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    I have family in welling mate. Occasionally I'm there. Should come say hello next time
  4. stevegti2
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    stevegti2 Member

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    ahhh i see im like 20 doors down same side of road dads place but garage is all mine lol ive seen your car around ill beep next time i see ya a fellow a3 owner rare lol :)
  5. Jay A3
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    Jay A3 come fly with me

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    Got to stick together... I will keep an eye out for your motor. I think I know where abouts you mean.
  6. stevegti2
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    stevegti2 Member

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    ive got my project car there just a suzuki swift chassis in the garage im always outside lol
  7. Jay A3
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    Jay A3 come fly with me

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    Me thinks me need a new maf!
    Hope this video works

    [​IMG]

    Unplugged mag and no different to the engine. What do you think?
    Last edited: Aug 20, 2012
  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    You really need to drive it with it off and see how it feels.

    What makes you think its faulty?
  9. Jay A3
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    Jay A3 come fly with me

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    Its idling inconsistently and occasionally it drops idle to 500 revs then cuts out. I thought if the maf was unplugged and the engine didn't do anything then its not working? I will have to take it out for a spin at lunchtime with the maf unplugged to see if it makes any difference

    What else could it be?
  10. Jay A3
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    Jay A3 come fly with me

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    Ok I unplugged the maf Ang plugged the n75 back in. Took it for a spin and I can't boost past 5psi at all. Idling seems to be the same as when the maf was plugged in. Any ideas??
  11. Prawn
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    Prawn My other car is a MINI!!!!

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    my AGU will barely run AT ALL with the MAF unplugged, it's not like mE7.5 cars and replies on the MAF much more than the others do. If you're is dodgy I'd get it swapped out asap.

    Do you not get any fault codes when this random boost loss happens?
  12. Jay A3
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    Jay A3 come fly with me

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    Yeh it ran ok when the maf was disconnected, idle dropped every so often, but unplugging the maf, can it stop boosting over 5psi?
    Scanned it before and nothing came up. I think the only thig that came up prior to the turbo change was something to the "power train"
    Not got in touch with anyone to scan the car today.
  13. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    unplugged maf = limp mode = 5psi.
  14. BENJAMIN
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    BENJAMIN Member

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    Car will still boost past actuator pressure with maf unplugged.
  15. Jay A3
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    Jay A3 come fly with me

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    [SUP]Didn't think the agu had a limp mode (sorry with the noobie comments)
    Apart from scanning the car for faults are there othe scans I can do? I.e logging specific blocks?
    Or other ways of testing to try and eliminate parts one by one?[/SUP]
  16. Jay A3
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    Jay A3 come fly with me

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    Ok so I plugged the maf back in and the car is running fine. Boosting normal now, idle bounces slightly. Drops more when stationary and I turn the steering. But the power is there, i am just waiting for it to happen again. It's like Russian roulette at the minute; one day it will run sweet the next who knows!
  17. CHEZ
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    CHEZ moderately amusing

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    jay! might sound daft! (because i am daft) but when was your fuel filter changed?
  18. Jay A3
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    Jay A3 come fly with me

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    About two weeks ago mate..
  19. Jay A3
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    Jay A3 come fly with me

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    Small Friday update

    Got to spend a little more time diagnosing the car to find out this boost related issue
    The local VAG specialist ran vagcom and tried to test everything he could... maf readings were a little higher than normal as well as fueling but nothing to cause the max 5psi boost.

    Checked all the pipes we could and everything seemed in order... We were really stumped
    He then focused on the N75, checking the pressure to the acutator. All seemed within reason so back to the drawing board.

    Google how we could test the N75 and came to this:
    N75 wastegate actuator valve explained/symptoms. - AudiWorld Forums

    More importantly the bit about testing the ohms
    Warmed the car up and the N75 had a reading of 38.9ohms which is nearly 4 ohms over the tolerance and could be the cause of the intermittent boost. The reading should always be between 25-35ohms whether its cold or hot. So now we have a lead!

    The question now is what can i do to reduce this? This N75 and the previous N75 suffered the same problem, so i dont think changing it again would cure it. I did get suggested to wrap the valve up with some sort of heat shielding.. can that work!?
    I see the logic behind it..."Reducing the heat from the N75 so it doesn't read such high ohms"
  20. Jay A3
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    Jay A3 come fly with me

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    I also tried to tidy up the bay a bit more and help reduce the amount of hot air getting sucked in. The bay is hot enough as it is!
    Thanks to S3 Dave for the heatshield, scott B5 and Devon Sign company i got to put this little thing together.

    [​IMG]
  21. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    i seriously doubt the exact resistance of the N75 coil will cause you to have no boost.
  22. BENJAMIN
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    BENJAMIN Member

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    Buy a maf! ;)
  23. BENJAMIN
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    BENJAMIN Member

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    When the car starts misbehaving, check the voltage to the n75 valve. Your problem could well be a wiring fault. The n75 gets its power from the 14pin connector block on the inner wing behind the battery, check there's no corrosion or water ingress.
  24. Jay A3
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    Jay A3 come fly with me

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    Ok so it may not exactly be the n75 but somewhere along the lines it's malfunctioning... I will check the wiring tomorrow. I will also check the resistor reading on a cold engine.

    The boost issue seems to happen when the engine is hot. The cutting out / idle could be related to maf or ignition module (yes Benjamin I shall buy a new maf soon)
  25. beachbuggy
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    beachbuggy Well-Known Member

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    Have you run the car with n75 unplugged? Do you get a consistent 5-6 psi when the car is running.
  26. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Any VCDS errors at all? Have you checked any N75 blocks in there, might be helpful.
  27. Jay A3
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    Jay A3 come fly with me

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    Dan I unpluggedd the n75 and it boosted to 5psi, plugged it back in and unplugged the maf still only got 5psi. Plug all back in and it works fine for now.
    Westy I have tried to scan anything and everything. If you can advise what blocks I should be scanning?
  28. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    MAF unplugged will almost certainly give you limp mode on an AGU.

    ME7 ECU's might be able to keep boosting with no MAF as it has a seperate boost sensor, but an M3.8 one wont.
  29. bigal 1
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    bigal 1 Active Member

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    Prawn here:

    Jay: have you checked the N75 wiring into the plug at all? I had the same issue at a trackday recently, car would randomly drop to actuator pressure. thought it was the N75 so swapped it out in the morning, problem still there, eventually pulled back the casing on the wiring to find that the thin strands had cracked and seperated. In close proximity they made contact and I had boost, then every so often due to vibration they'd drift apart and it'd drop to actuator again.
  30. Jay A3
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    Jay A3 come fly with me

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    Thanks chaps. Yeh the wiring is on the agenda today, well that and the mot. I will have a closer inspection this afternoon!
  31. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    I had this on my old A4, but it did log a fault code for N75 open circuit, intermittent.
  32. Jay A3
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    Jay A3 come fly with me

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    The code did come up but that was because I had recently unplugged te n75. Cleared it yesterday, ran it and hasn't come back. Although saying tht neither has the boost issue... I will check wires today. When the problem happens again I will scan it to see if the intermittent code comes up.
  33. superkarl
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    superkarl MAN OF STEEL

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    hopefully you'l see a trend of when the boost dies you get the open circuit fault. No one likes tracing faults that are *** impossible to find.
    good luck jay.
  34. Jay A3
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    Jay A3 come fly with me

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    Didn't get a chance to check through the wires and loom today as i had to sort out 2 bald tyre's
    (Outside of them still new but inside both fronts were completely bald)

    Anyway i changed those, and car also went in for an MOT
    Passed with an advisory - my inner track rod was gone... One call to Euro car parts, half an hour later i get a new rod for £15!
    TPS wanted £100+ for the inner track rod and track rod end... So i spent the afternoon changing that with my brother. Not a long jobbie... the Killer bit was removing the old track rod end where it was seized. Out comes the blow torch!!!

    Late in the day and i was unable to go and get the tracking done.. Looks like a job for Tuesday

    Half hour before the garage closed we decided to fit the Lcr splitter
    This was thanks to Karl (Seen it on his car and loved it) and thanks to Benjamin for getting hold of one for me!

    Plenty of self tappers and a bit of trimming: not the best picture but will get some decent ones soon

    [​IMG]

    I will be doing some long driving this weekend so i will see if the boost problem comes back...
  35. StaceyS3
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    StaceyS3 Well-Known Member

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    Nice work mate

    I've really got to get myself a lcr splitter after seeing Karls and now you've reminded me ;)
  36. Jay A3
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    Jay A3 come fly with me

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    Glad i could help haha
  37. Westy
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    Westy Double Dark Side! Diesel & 8P

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    You two plums! I've had the splitter on my car for ages and you've both seen that loads ;)
  38. Jay A3
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    Jay A3 come fly with me

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    i would have noticed if you had turned up to the show on time and parked at the front rather than right at the back! Plus when I look at your front bumper my focus is normally on the stone chips lol.

    Sorry westy I will look next time!
  39. StaceyS3
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    StaceyS3 Well-Known Member

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    Lol ;)

    Had seen yours Westy as well as others but seeing Karls eventually sold it for me as been thinking about it fir a while and was worried that I'd rip it off with how low mine is, but suppose the selling point was when the mrs agreed I should get one lol
  40. deeman88
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    deeman88 Watch this space...

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    Wow, I like the amount of progress I see bro. Hope no more lil issues pop up. Have you got the 25mm anti roll bar kit yet?

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