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1.9 tdi sport losing power at 3k and smoking a lot!

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by joshW, Jul 30, 2013.

  1. joshW
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    joshW Member

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    [Jul 30, 2013]
    Hi all, had my 1.9 tdi sport avant for a couple of months now. It's had a slight lumpy idle since I got it. I had it mapped about 3 weeks ago and all has been fine.
    I was giving it a bit the other night and then felt a loss of power and now when I accelerate, it pulls strong until it hits 3k revs and then loses power, goes really flat and pumps out a load of black smoke!
    Any ideas?
    Cheers
    Jake
    #1
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  3. stu_m
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    stu_m Active Member VCDS Map User

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    [Jul 30, 2013]
    sounds like its going in to limp home mode more then likely from overboost

    you need it scanning to know more
    #2
  4. joshW
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    joshW Member

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    [Jul 30, 2013]
    My mate plugged it into one he had which didn't throw up any codes.
    Take it I'd need a vcds scan
    #3
  5. stu_m
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    stu_m Active Member VCDS Map User

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    [Jul 30, 2013]
    ideally yes some generic code readers only pick up emissions related stuff
    #4
  6. stu_m
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    stu_m Active Member VCDS Map User

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    [Jul 30, 2013]
    oh and as for the lumpy idle that could be the synchro angle out again you need vcds to check

    if it is out its easy to adjust do a search there is some threads on it
    #5
  7. joshW
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    joshW Member

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    [Jul 30, 2013]
    Ok thanks mate. Ill take a look on the map to see if anyone's in my area
    #6
  8. Mike.M
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    Mike.M Well-Known Member

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    [Jul 31, 2013]
    Check hoses for boost leaks due to splits etc........this usually creates lots of black smoke when on the power pedal
    #7
  9. joshW
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    joshW Member

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    [Jul 31, 2013]
    I did have a quick look yesterday. Couldn't see anything but ill try having a closer look
    #8
  10. joshW
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    joshW Member

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    [Jul 31, 2013]
    On my way home today, I decided to try unplugging the maf just out of interest. It didn't smoke but had no power at all. It was really slow. But idle seemed a little smoother
    #9
  11. pauldazzle
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    pauldazzle Active Member

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    [Jul 31, 2013]
    I have VCDS, pm me if you want to hook up.
    #10
  12. stu_m
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    stu_m Active Member VCDS Map User

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    [Jul 31, 2013]
    you should never just unplug things as this will only cause confusion when it does get plugged in as it will probably be showing an error code for the MAF and would need to be cleared and checked again later on after a while of driving to rule it out
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  13. pauldazzle
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    pauldazzle Active Member

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    [Jul 31, 2013]
    Unplugging the MAF on Audi TDi's doesn't seem to work the same as on other VAG TDi's. The Audi ECU doesn't seem to revert to default setttings like a VW or Skoda. Seems to work on the Audi 1.8t's though.
    When the MAF died on my A4 unplugging it made no difference, it still had no power. New MAF fitted & all was ok again.
    #12
  14. DieselJake
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    DieselJake God Mode

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    [Aug 2, 2013]
    Seen this problem a few times (intermittent problem in my 1.9tdi too unfortunately), here's issues and claimed resolutions:
    Cleaning the EGR
    Broken engine mounts result in engine shaking
    Damaged boost pipes related to power issues
    For me nothing shows on VCDS but what cures the problem is always having over half a tank of fuel... don't quite understand this but there we go haha. Don't trust a money digging garage claiming they will cure this with an oil and filter change, but pretty much goes without saying.
    #13
  15. joshW
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    joshW Member

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    [Aug 2, 2013]
    I cleaned the egr about 6 weeks ago.
    The engine does wobble about a fair bit on idle so engine mounts will be worth looking at. Ill try have a look later and check boost pipes again
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  16. stu_m
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    stu_m Active Member VCDS Map User

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    [Aug 2, 2013]
    could also be sticking turbo vanes causing overboost

    you need a scan really to see whats happening
    #15
  17. joshW
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    joshW Member

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    [Aug 5, 2013]
    What should I be getting checked with vcds?
    Is just a full scan likely to throw any codes up? Or do I need to look into more?
    What would people advise checking while its plugged in?
    #16
  18. pauldazzle
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    pauldazzle Active Member

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    [Aug 6, 2013]
    You can do a full auto scan, but that takes a while. It's quicker to go straight to the engine module & click on fault codes.
    From the symptoms you described I'm guessing you're going to find an overboost code.
    Ah just noticed you have a 1,8T so ignore that it won't be an overboost fault.
    #17
  19. joshW
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    joshW Member

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    [Aug 6, 2013]
    No I don't. This is my brothers old account. I've gotta set up a new one. It's a 1.9 tdi a4 avant sport.
    #18
  20. pauldazzle
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    pauldazzle Active Member

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    [Aug 6, 2013]
    Ah well sticky turbo vanes is the most likely culprit, which will give an overboost fault code. Mr Muscle fix usually solves the issue.
    #19
  21. joshW
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    joshW Member

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    [Aug 6, 2013]
    Don't know anything about that mr muscle fix. Ill search it later. Cheers mate
    #20
  22. adamss24
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    adamss24 Well-Known Member

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    [Aug 6, 2013]
    take the rocker cover off and look at the cam, chances are the cam lobes are worn due to lack of servicing and incorrect oil grade !
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  23. joshW
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    joshW Member

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    [Aug 21, 2013]
    Had it scanned with vagcom last night and it didn't show any codes. Well only signal too low for my air con sensor.
    It could do with a service so ill do oil, oil filter, air filter and fuel filter. Ill also do the mr muscle on the turbo and see how it is after that.
    #22
  24. audilad9
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    audilad9 Member

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    [Aug 22, 2013]
    As well as an A4 tdi, I have a VW caddy tdi and had this problem last week. It has been remapped giving increased boost. It was going into limp mode at 3000 rpm. I figured overboost. I don't have vcds or any fault reader yet but am going to get it soon. I ordered a used 3 bar MAP sensor from ebay (£10) standard sensor is 2.5 bar, and problem solved, goes like a rocket :)
    Anyway I was lucky. Hope you get sorted.
    #23
  25. joshW
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    joshW Member

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    [Sep 8, 2013]
    Well today I did the mr muscle on the turbo and its still the same! I'm sure it was only a couple of weeks after the map that it started so I may contact who did the map and ask them
    #24
  26. adamss24
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    adamss24 Well-Known Member

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    [Sep 8, 2013]
    Take that rocker cover off and stop beating around the bush ! It will be obvious if the cam lobes are worn as they will be rounded off and with sharp edges, good cams have beveled edges so they don't cut your fingers !
    #25
  27. joshW
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    joshW Member

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    [Sep 8, 2013]
    Will try this tomorrow if I get time.
    #26
  28. joshW
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    joshW Member

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    [Oct 11, 2013]
    Changed the maf Wednesday evening and it seems a little better but definitely not right.
    I've noticed that the last two mornings, if I put my foot down from cold, it pulls fine in all gears up to 4k no probs. then as it starts warming up, second gear is fine but third loses power and smokes again. Then once up to temperature, same in all gears.
    Any ideas anyone? Hoping that the fact it's fine when cold may suggest something
    #27
  29. pauldazzle
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    pauldazzle Active Member

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    [Oct 11, 2013]
    Coolant temp sensor is one of the most common failures on VAG cars, & causes all sorts of running problems.
    If you can get to me in east Cardiff I'd be happy to scan it with VCDS.
    #28
  30. joshW
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    joshW Member

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    [Oct 11, 2013]
    I thought coolant temp sensor, but wouldn't of thought that would cause issues this bad. My mate scanned with vcds a few weeks ago and no codes came up.
    I drove it to London last week and after being on the motorway for a while, engine management came on so my mate plugged it in with a generic reader and it came up with p1556 boost variant negative or something.
    #29
  31. joshW
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    joshW Member

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    [Oct 11, 2013]
    It's having oil, oil filter and air filter done tomorrow, so while we have it on a ramp, were gonna check boost pipes and vacuum lines to see if there's anything damaged.
    From what I've read about that fault code, it seems it's either vacuum lines, actuator or sticking turbo vanes.
    I just thought its worth mentioning about it running well in the cold in case it points to anything specific
    #30
  32. pauldazzle
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    pauldazzle Active Member

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    [Oct 11, 2013]
    17964/P1556/005462 - Ross-Tech Wiki

    It won't be sticking turbo vanes as that applies to VNT turbos on TDI's.
    Split vacuum/boost pipes are extremely common on VAG 1.8T's especially all the pipes around & under the inlet manifold. If you can hear hissing in the engine bay with the engine at idle then you have a split somewhere.
    CTS failure will only throw a code if the CTS has gone open circuit or intermittent. If the ECU is getting a reading from the CTS it won't throw a code even if the reading is wrong, so the only way to check it properly is measuring blocks in VCDS.
    Generic scanners don't recognise all VAG fault codes so you can't rely on them for correct diagnosis.
    #31
  33. joshW
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    joshW Member

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    [Oct 11, 2013]
    Yeah I've got an a4 1.9 tdi. This account is my brothers old one.
    Oh so a coolant temp sensor could be worth trying then?
    #32
  34. pauldazzle
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    pauldazzle Active Member

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    [Oct 11, 2013]
    Ah ok so it's TDI.
    If your CTS is black you definitely should change it out for a genuine VAG revised green CTS. (Warning when it comes to VAG engine sensors buy cheap, & you'll be buying twice).
    Cleaning the turbo with Mr Muscle probably wouldn't be a bad idea too. There are guides on here so have a search.
    #33
  35. joshW
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    joshW Member

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    [Oct 11, 2013]
    I did give the turbo a clean with mr muscle a few weeks ago but made no difference at all.
    #34
  36. pauldazzle
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    pauldazzle Active Member

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    [Oct 11, 2013]
    Ok, well I think you can eliminate that.
    If you have access to VCDS go in to engine blocks & do an instrument test. Amongst other things it will test the N75 which is one of the things listed on rosstech wiki for dtc 1556.
    #35
  37. pauldazzle
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    pauldazzle Active Member

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    [Oct 11, 2013]
    There are a bunch of braided vacuum pipes which are prone to splitting. I replaced all of mine a while back as some didn't look to good. Really cheap & easy to do.
    When you did the MR Muscle fix did you check if the turbo actuator was moving smoothly with full travel?
    #36
  38. joshW
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    joshW Member

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    [Oct 11, 2013]
    I could pull the actuator rod up, but it did take quite a lot of pressure. Not sure how hard it should be but it was pretty hard. And would spring back down when released. Think I've got some pipe here for the vacuum lines so I'll replace what I can tomorrow. I'll also speak to my mate with vcds and see if he's free. So what things should I check? N75? How will I know if it's working? Also how do I check the cts?
    Anything else I can check with that to eliminate anything?
    #37
  39. joshW
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    joshW Member

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    [Oct 11, 2013]
    Ok just been for a quick look at the car. When I put a new hose onto the top of the actuator, I could suck and feel the rod coming up, then returning back down when released so I'm assuming this rules out sticking turbo vanes and leaking actuator?

    When I disconnected the vacuum for the egr and blew down it, I could hear a hissing coming from down by the air box. I think it sounded like it was between the air box and headlight.
    Have I got a leak or is this where the egr gasses are released back into the intake?
    #38
  40. joshW
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    joshW Member

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    [Oct 11, 2013]
    Sorry it was the vacuum line to the anti shudder valve I blew down
    #39
  41. pauldazzle
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    pauldazzle Active Member

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    [Oct 11, 2013]
    Sounds like you've got some dodgy pipework. The N75 is down there just below the turbo actuator so you may be on to something.
    With the engine fully warmed up go in to VCDS engine measuring blocks & you can see the temp the ECU is getting from the CTS. It should be about 88 degrees.
    #40

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