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Boost Issue - It's Flat

Discussion in 'A3/S3 Forum (8L Chassis)' started by JamJay, Jun 5, 2011.

  1. JamJay
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    JamJay Member

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    1.8T & K04 LCR.

    Right, so the car revs to redline and boosts somewhat but it's lost it's urgency and punch in the back, obviously acceleration is slower too, much slower. I have no fault codes and ive tried all three DVs (007, split-r and OE) but I have noticed that the DV blow off sound is quieter so I guess I've lost boost somewhere.

    The car was fine yesterday morning, gave it some beans & it pulled hard. On the same jounrey I went to accelerate again and where it would normally throw me in my seat at 2500rpm, I get nothing, just hestistant (in comparison) progressive power, almost like NA. Does this sound like a boost leak? I've checked the TIP and all is secure so I'd guess it's post turbo...or something else? Where should I be looking?

    Please help :(
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  2. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Have you tried logging any blocks?

    If you could go out for a blast and log the following blocks it might throw up some info:

    log 031, 115, 020 and this will give us an idea of what the car is doing under boost. Also what mods do you have? The logs will show if the ECU is pulling the timing at all or if EGT is kicking in.
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  3. JamJay
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    JamJay Member

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    Unfortunately for me my XP laptop is dead, real dead so I'm stuck with VCDS Lite on my Win 7. I think I can log 020 on this, maybe 034 to show fuelling which may give an idea or boost? 115 & 118 were ideal on my old laptop but it's a no go.

    Mods:

    - B5 TIP
    - 3" DP & Race-Cat
    - 3" Cat-back
    - 007 DV Yellow Spring
    - Stage 1 AMD Map
    - Jetex Cone Filter
    - 2mth old MAF
    - Proven to work (1mth ago) OE N75
    - N249 Bypass
    #3
  4. Westy
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    Westy Double Dark Side! Diesel & 8P

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    So chance EGT protection is kicking in would be lower than normal as you have a 3" DP and exhaust system. Possibly ignition timing due to no FMIC but you'd need to log the blocks above to get an idea.

    Try logging air intake temps on block 118 and see if they are particularly high when you notice the "flat" issue.
    #4
  5. Sandip
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    Sandip Well-Known Member

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    By the sounds of it you're in limp mode, did it happen all of a sudden whilst driving, after being on full boost perhaps??
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  6. JamJay
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    JamJay Member

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    TBH I'm stuck unless I have a local member with full VCDS :(
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  7. JamJay
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    JamJay Member

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    Yep. Full boost and fine, off boost for a small period and then tried to hit it again and nothing...just an NA non-turbo feeling and has been the same since. However I have no error codes.
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  8. Westy
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    Westy Double Dark Side! Diesel & 8P

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    I had a period of hitting soft limp mode due to a faulty N75 that was causing some over boost. I was however getting a code :think:
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  9. Sandip
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    Sandip Well-Known Member

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    That's strange, it sounds a bit like what mine was doing but i had an overboost error code. Yoi might have already checked but if you haven't, check the red chargepipe to turbo hose
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  10. JamJay
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    JamJay Member

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    It might be worth montioning that since I added 3" TIP & 3" Exhaust I have experienced an overboost issue. Could it be that after a few weeks of this, it has finally decided to go into limp mode? I've had the car apart many times in many places and all have said that I need Stage 2 code. However I am waiting on a FMIC to turn up before I can get this done and still then, AMD won't be happy to map the car in limp mode.
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  11. JamJay
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    JamJay Member

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    I fitted a Forge one last week, it feels like it's on but that mani-melted part of my hand so I'll have a reach down again tomorrow.

    P.S. My overboost never threw a code at all throughout all the weeks.
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  12. Sandip
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    Sandip Well-Known Member

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    Check the hose, i actually took mine off today because it's popped off about a hundred times in the past month lol

    The jubilee doesn't seem to fit and hold the hose as well as the oem hose (on mine anyway)
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  13. JamJay
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    JamJay Member

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    Maybe the Forge one is a bit of a bum hose, the OE one I removed looked brand new so perhaps it has come loose. It's raining so hard here right now so I can't do much as we speak but on the list for tomorrow is to check my N75 connections and the TOP. I'll report back but I have also found a local member to log my car next weekend so that'll help things...I hope.
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  14. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Just to mention that my N75 didn't throw up a fault and the duty cycle was all good on VCDS but as soon as I fitted a new one the problem went away immediately.
    #14
  15. JamJay
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    JamJay Member

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    Cheers Westle, it's a risky game throwing money at sensors though. Been there and lost a lot of money but I'll bare that in mind as a last resort.
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  16. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Borrow one mate. There's a few members here that I'm sure would be willing to lend you a known working N75 valve for testing purposes. I don't just chuck money at sensors either. I borrow what I can from S3 Baby and let him chuck his money around ;)
    #16
  17. JamJay
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    JamJay Member

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    Haha love it, I'll see who's around this week.
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  18. JamJay
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    JamJay Member

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    Right...

    *N75 unplugged and reconnected to make sure it's on - No change
    *Checked that that Forge TOP hadn't slipped, all was ok
    *Battery neg terminal disconnected for 30mins and reconnected to reset ECU - No change
    So I guess I am looking for a boost leak or the N75 has gone? I need to borrow an N75 before wasting money on one though.
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  19. JamJay
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    JamJay Member

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    Ok, so a little update...

    - I just scanned the car...again and no fault codes.
    - I then unplugged the MAF, went for a drive and the car performed the same. I stopped and rescanned the car and got the MAF signal too low code, plugged in the MAF again and cleared the code.
    - I then unplugged the connector from the N75, went for a drive and the car again performed the same. I stopped and rescanned the car and got the N75 no signal code which I have now cleared.

    So does this show anything up? MAF is 2mths old, if that but the fact that the car behaved the same with N75 unplugged, would that point towards dead N75?
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  20. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Sounds like permanent limp mode to me but strange there's no fault code. Have you got a boost guage?
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  21. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    Sounds like mine jay, mine drives fine but just down on boost, tried all sorts so far and no luck either.
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  22. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    It really needs some more blocks logging.

    I had an issue that presented similar symptoms, the FPR was clogged full of rubber due to faulty fuel lines and as a result it ran rich and went into limp. It did throw a fault code eventually though...

    Boost leak could be an issue but with more logging it's guess work really.
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  23. JamJay
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    JamJay Member

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    It's just so strange how one moment I have all boost and the next I have nothing and now it's stuck in limp mode. It's due a Stage 2 map so I might just chuck it into AMD for it all to be done. Fed up with 1.8t ownership, I just want this sorted, get summer done and bye bye.
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  24. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Dont be like that mate. It'll probably be something silly that AMD will pick up straight away and fix then you'll love it again.
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  25. JamJay
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    JamJay Member

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    I really hope so, I used to get in this thing and smile even on a trip to the shops...it's such a bummer that it's slowly trying to kill itself. I've arranged an N75 swap tomorrow, PCV pipe, jubilee clip, DV & FPR vac line replacement for Saturday as well as fitting a Forge FMIC so I can have a look down there also. If none of these I have been advised to reset the ECU via VCDS as the Split-R I had may have thown this up but I'd have thought as soon as the 007 went back on the car would go back to normal? I'm also going to take the Forge TOP of again and refit just in case...after that who knows, AMD will have to have a look. I hope it's not turbo actuator but that seems fines, the turbo is working and dumping pressure, just not a lot of it. When I put my foot down the tubo sounds like it always did to a point but then just can't seem to push the performance, I have right now what feels like a well powered NA car.

    I have also arranged logs on Sunday, I will log 002, 003 & 020 together, then 115, 118 & 032 together...will those be ok for you guys? I don;t have a boost guage which sucks, I could buy one but I kind of think I might need the money to fix it :)
    #25
  26. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Yeah get them logs up mate.

    It could be worse, I've just spent nearly £2K on mine this week including a brand new K04 as my old map murdered my last one! I still get in the car and smile :)
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  27. JamJay
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    JamJay Member

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    That really is love for your car, I hope I get mine back :).
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  28. Westy
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    Westy Double Dark Side! Diesel & 8P

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    I've gone past the point of no return with it. I've had problems with it that have mad me loose interest but as soon as its sorted I'm back in the seat with love for it again. You'll get your smile back mate :)
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  29. JamJay
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    JamJay Member

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    I had this one keyed and also some fluid of some sort bleached my paint. I paid for a whole respray so it looks like the freshest yellow LCR around, it just doesn't go :). Fingers crossed massively for the N75 tomorrow but if not then at least it's another off the list but I'm running out of mechanical knowlege rapidly, would rather not have to pay AMD to diagnose as I would like to use the money elsewhere but I have to get this done one way or another. Thank God for ASN & SCN!
    #29
  30. s3dave
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    s3dave TFSI Hybrid

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    Agreed they do test your Patience for sure, but jamjay you will get it sorted bud....
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  31. JamJay
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    JamJay Member

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    Right'o,

    I just want to say a massive thank you to my friend Jay, he leant me his N75 this afternoon and stuck with me through some unforseen issues. Absolutely top guy.

    So let's outline the day. I arrive at my Jay's house and begin to remove parts from mine and his cars, I disconnect the Negative terminal on my battery, disconnect the N75 and remove it. I then replace my N75 valve with Jay's and I discover that it's a 'J' but it's a working one, that's all that matters [​IMG]. 30mins later my battery get reconnected, I tighten the bolt and nut that clamps the terminal only a little way and the bolt snapped completely in half! Ok, no biggy, we'll go to a motor spares shop and buy a new bolt...could I? NO! Nowhere sells them so a quick call to TPS & VW reveals that the bolt comes as part of the terminal AND wiring harness assembly = £35 or there about. Head scratching, Jay comes out from his house with a bit of old silicone hose which we wedge between the terminal and battery cover to stop it popping off, we then decided to go to a scrap yard in search of a MK4 Golf.

    The journey starts and I pretty much wipe out my splitter on a speed hump, it's ok but needs a rub back lol. Hit the road and I put my foot down, wow, the car is about 90% back to life...big smiles although I can feel that it's still not 100%. On the dual carriageway I look in my rear view mirror and see a white van storming after us, put two and two together and I knew it was a police van that we passed 1min ago but as I am doing the speed limit I don't worry too much. The van closes in quick so he must have been doing 80mph to make up some distance (50mph limit), sits on my bumper and then the blue lights flash...great! Pull in, the policeman comes to my window and tells me I was speeding, I say no I wasn't, he says yes I was blah blah blah but anyway as he can't prove complete fallacy he tells me I am lucky and he has to be somewhere else...waste of time.

    We make it to the scrap yard and hunt for a MK4. Half way round we get called over by a pikey who needs tools, like they always do. Fair enough, nice guy actually but we didn't have time yet we find ourselves helping him remove two headlamps from an old battered Transit van. A few sheared bolts later and we're on the hunt again, no Golfs but one Arosa with a smaller bolt which ended up being too small, luckily we looked in an mk5 Escort and it had the exact same termail type as the Leon. Job done, new bolt fitted and away we go.

    The car is still running well at this point and I have boost, but something is still up, hopefully the logs on Sunday can help here [​IMG]. I do wonder maybe if the fact I fitted a 'J' valve would make it run a little off as it's mapped for abn 'F' valve? Either way was better than with my old valve.

    I refitted my old valve and gave Jay back his, the car goes back to being flat and boring so I don't think this is limp mode at all, it's just a shagged valve not working and only giving me actuator pressure.

    We also had to pick up some parts for Jay and they forgot a pretty major part that he needed...a day in the life of my Leon eh? [​IMG]

    So, I think I need to get a new N75 on order.
    Last edited: Jun 8, 2011
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  32. s3dave
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    s3dave TFSI Hybrid

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    Well at least your getting somewhere well done...
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  33. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    The joys of car ownership and maintenance!

    FYI - Regarding the N75, the 'F' has recently been superceeded by part number 06A 906 283 E.
    #33
  34. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Sweet. Get a new N75 and you'll be in love with the Leon again :wub:
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  35. JamJay
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    JamJay Member

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    Thanks guys, I really hope this fixes it. I've just ordered a new one and I'll report back once it's on :).
    #35
  36. JamJay
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    JamJay Member

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    Thank you everyone for your advice, I really appreciate it all. I found the culprit, it was the N75. By the looks of it, it wasn't bleeding any pressure into the TIP and was just bleeding it all into the wastegate.
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  37. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Glad you found the problem mate. Do you love the car again now?
    #37
  38. JamJay
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    JamJay Member

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    Yes I pretty much do, I gave it some love this weekend and installed this baby too...

    [​IMG]

    TBH this and the new N75 have cured about 99% of my issues, the rest I believe is down to mapping and the lack of a 4bar FPR, both of which are on the menu this Saturday :)

    If I could mod again I think I'd go for Stage 2 all at once with the money and parts saved up, I'd also buy a new MAF, new N75 and new coilpacks at the start of ownership as spares.
    #38
  39. Westy
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    Westy Double Dark Side! Diesel & 8P

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    I knew you'd love it again.

    You dont need a 4 bar FPR for stage 2 though, or is this a Seat thing?
    #39
  40. JamJay
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    JamJay Member

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    Some maps do, some don't but my IDCs are maxed out so the 4bar will fix that...if only just temporarily while I consider which 440cc's to go for. Saying that I've never heard of a fuel pump failing due to higher fuel pressure and it's rumoured that 3bar was only fitted to help the engine fall within EU emmission and fuelling regs. Either way, the old girl is screaming for more fuel that the 3bar just can't give.
    #40

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