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2.0 tdi hesitation/stutter between 1400-2000rpm

Discussion in 'A3/S3/Sportback (8P Chassis)' started by rickyquicky, Jul 15, 2010.

  1. rickyquicky
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    rickyquicky Member

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    Any of the TDI owners experienced this?

    When accelerating my car is fine, but between around 1400/1500 and 2000 rpm it will hesitate on and off a few times and then be fine after 2000rpm.

    Apart from that the car is fine, happens in every gear and any speed.

    Any ideas?
    #1
  2. GAudiTech
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    GAudiTech Member

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    sounds like a fuel issue. Common problems are tandem pump leaking internally causing oil contamination in fuel (take sample). fuel leaking passed injector seals and injector seats ovaled on cylinder head
    #2
  3. rickyquicky
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    rickyquicky Member

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    Cheers for the info, wheres thre best place to take a sample of fuel to check for oil contamination?
    #3
  4. rickyquicky
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    rickyquicky Member

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    Also noticed tonight that when its hesitating, I can hear the dump valve realeasing boost on and off at the same time as the car is hesitating if you know what I mean...like if it stutters say 3 or 4 times in quick succession, I can hear the dump valve in sync with it letting off boost every time it stutters?!
    #4
  5. devonmikeyboy
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    devonmikeyboy As far from JBS as possible !

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    Your car doesn`t have a dump valve it`s diesel.
    #5
  6. j50sho
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    j50sho Member

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    Got the same problem here mate, I've just had a new maf as it was on the fault code but still does it every so often! Try driving in first gear and hold the revs just below 2k , mine jerks like mad at this point. Normally around the 2kmark it will blip the power on a normal run though. Any other ideas?
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  7. rickyquicky
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    rickyquicky Member

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    Whatever its called surely you know what im trying to say?

    When my car changes gear I can hear pressure being released from the turbo.....whats releasing this pressure?
    #7
  8. rickyquicky
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    rickyquicky Member

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    Is yours a tdi too?
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  9. GAudiTech
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    GAudiTech Member

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    Take a fuel sample from the feed pipe to the fuel filter. I take it you have also checked for fault codes?.
    Last edited: Jul 17, 2010
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  10. GAudiTech
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    GAudiTech Member

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    I would be taking a fuel sample as well.
    #10
  11. rickyquicky
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    rickyquicky Member

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    I've checked and there are no fault codes logged btw
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  12. waring192
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    waring192 Member

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    Sounds very similar to what happens on my s3
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  13. j50sho
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    j50sho Member

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    Yep mines a 2.0tdi BKD engine, only fault that poped up was MAF which I replaced, it didn't do it as much after but is still doing it. Its as if it blips and loses power for 2seconds.. Take a fuel sample you reckon?
    #13
  14. j50sho
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    j50sho Member

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    Btw... Have u had it mmapped? I've only had the problem after getting it remapped and giving it some stick.
    #14
  15. jameshughes1974
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    jameshughes1974 Member

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    Do you hear the sound when you come off throttle for example as you come of the throttle to change gear.
    Makes a bit of a hissing sound?
    If it does you probably have sticking vanes in the turbo or a boost leak.
    Boost leak would be easier to fix!
    The BKD diesel seems to have a particuler problem with sticking sooted up vanes.
    Best to check all other options first thought as getting the turbo off isnt easy.
    There is a chemical cleaning solution called innotec but ?I have never tried it myself.

    If your realy lucky taking it for a high reving fast drive may blow the soot out.
    Its caused by a combination of the exhaust gas circulation oily sooty gunk and the very low down torque in the BKD engine which tends to stop people going into the high revs that would actualy clean them.

    Good luck this subject can be a real can of worms
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  16. rickyquicky
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    rickyquicky Member

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    Yeah mines been mapped mate, since December though and it used to be fine.
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  17. rickyquicky
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    rickyquicky Member

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    When it stutters I can hear 'tsss, tsss, tsss' that is in sync with the hesitation. Only happens 2 or 3 times up to about 2000/2100 rpm then its perfect all the way to redline. Its the same faint noise as what you get when you change gear in a 'healthy' car.

    Also if I floor it in a low gear and then quickly comes off the throttle I get whats sounds like a whirring/fluttering noise from the turbo, rather than the familiar 'tshh' (lol @ trying to spell how noises sound!)
    #17
  18. jameshughes1974
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    jameshughes1974 Member

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    On these cars the vanes are controlled by a vacuum actuator by a map in the ecu referencing specified boost v actual boost. Boost is measured by the map/maf(what ever you want to call it- that bit in the air intake that a lot of people change on the way to the real fault).
    If to much boost is detected their is less vacuum and vica versa. The tsss tsss tsss sound like the actuator is moving back and forth to find the right place (boost)
    to be at.
    Try holding the car in neutral at the rpm you hear the noise and see if the rpm pulses around the rpm you set it to with out you moving the throttle. mine can be set to 3200 rpm and will move 3100 - 3300 without me moving the accelerator.
    Mine also whirrs and flutters in a worrying manner when i come off throttle suddenly.
    The bottom of my intercooler pipe connectors are weeping oil but that might be expected considering its over boosting.

    I am not sure about the fuel oil analysis because the egr pumps semi burnt exhaust fumes straight back into the engine anyway so its not as if they cant handle it. as long as a metered amount of fuel comes out of the injector it should be ok. If your tandem pump is dripping oil and fuel down the end of the block then that's a different matter! I have a feeling that there are so many sooted up bkd turbos that everybody thinks the noise is normal, I think they just haven't tripped a fault code yet. I have driven plenty of other Audi tdi's and non of them sound like the bkd. In fact the only other non bkd audi tdi making anything like this noise has a positive deviation error which is a fault relating to boost aka turbo vanes not in the right spot. If I remove the vacuum hose on mine whilst being slower to spool up it if I come of throttle suddenly in neutral it does spool down like every other tdi I have driven.
    I have taken my turbo off once and freed off the vnt lever but I couldn't crack the turbo open to clean the insides. I am taking it off again to get it cracked open with a heat source so I can clean the vanes, there is a tech article on the web which said freeing the lever off without taking the thing a part is unlikely to fix the issue and it was spot on.
    Garages replace turbos rather than cleaning them as the time to clean it is the same cost as the part of a recon one – but if you do it yourself its worth cleaning it.
    The horror stories of turbos exploding are when they fail unsafe – ie the vanes stick in a overboost causing the turbo to revolve to fast. Mine is ok as the turbine has no play in it.
    I will post my results but it could be a while as I dont like the rain dripping in my face when under the car. I have vagcom and it showed actual boost consistently higher than specified. I tried the same test on a 1.9pd and it was a lot closer to the specified and sounded normal as well. Not sure where I am going with this post other than I think it might be worth you reading it. Would be great if a non noisy bkd engine could have its boost logged and the results put up so all us noisy bkd,s would know if our cars are working.
    If you get a fix please post it!
    #18
  19. jameshughes1974
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    jameshughes1974 Member

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    Getting a remap probably wouldnt cause it.
    Proper remaps tend to get blamed for causing problems when what they actualy do is highlight a problem that was there all along.
    #19
  20. rickyquicky
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    rickyquicky Member

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    Thanks for the info James, glad to hear that someone has some experience and give me an idea whats up with the car!

    Let me know how you get on if you do get round to cleaning your turbo :thumbsup:
    Last edited: Jul 20, 2010
    #20
  21. dunk
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    dunk Member

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    my bkd also does this kind of boost hicough, but only on partial throttle, somewhere between 2000rpm and 2400rpm - its very occasional, and nobody can find a fault

    mines a brand new hybrid and definately doesnt have sticky veins or any mechanical problems
    if you log the ecu, boost request drops for a fraction of a second, and the turbo and controller does its best to do what was requested.

    also if you log fuel, throttle position or anything else, there is nothing abnormal to find =so the ecu seems to temporarily decide to dump all the boost for no apparent reason.

    if you use a standard map, it still does it but its less noticable
    adding a normal remap, its more evident
    adding the hybrid turbo map with 1.8bar boost, its much more obvious, but only because the change in boost pressure is so much greater then the other ones

    so it doesnt appear to be an turbo or vane fault, its not the MAF cos i tried that as well, its not map dependent other than more noticable with more boost, its not a boost leak either.

    maybe there is a fault in audis original ecu code with the bkd and edc16 combination?
    #21
  22. jameshughes1974
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    jameshughes1974 Member

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    took my turbo off this evening and the lever to move the vanes has stiffened up considerably since I freed it off without taking the turbo apart- this confirms the tech article I found saying it needs to be taken apart and cleaned so I will be looking to get somebody with a proper blow torch to split it open for me.
    Dunks post seems pretty good info and does indeed sound like a software bug in the ecu. So perhaps you are dealing with two faults 1. the hesistation bug 2. noise off throttle probably vane related. There is probably nothing to be done with the hesitation but i would start periodicaly exploring the higher rev range of your engine to burn the soot out of the turbo before it trips a fault code. Dunk did you change the turbo because the old one was making noises coming off throttle or part of a quest for bhp, either way it would be good if you could confirm if the original had that dumping pressure sound - thanks
    #22
  23. jameshughes1974
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    jameshughes1974 Member

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    Does the hesitaion only happen when it warm?
    The BKD has the egr which also runs through the cooler thing -boost can be dropped by a leak or suddenly making the boost container bigger ie that valve in the egr cooler opens which effectively adds more volume to the inlet pipe work - not much but maybe enough to make a hesitation.
    This is where dunk tells me he has done an egr delete and blows that idea out the window!
    #23
  24. phil_w
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    phil_w Member

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    I had a 56 plate GT TDI Golf that did exactly the same - dealership could never find a fault or apparently ever make it do on a test drive - since spoken to my mate who inherited the car from me (it was a company car) - he has exactly the same issue so it wasn't just me!
    #24
  25. Gti Jazz Blue
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    Gti Jazz Blue Active Member

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    Stick vanes is a very common issue with the BKD - my mate works in a General Garage, they change loads of them due to sticky vanes. Usual mileage is 50K upwards - though they have done some with lower miles on them.

    I have a hesitation on part throttle round about 2K (usually in 3rd) and I can here a hiss - just haven't got round to a VCDS logging session yet to check the boost. I did have an overboost code about 6 months ago - but nothing since I reset it.

    Thinking of a Turbo Back Milltek, so will probably consider a recon Turbo at the same time as mine is at 70K.

    Paul
    #25
  26. jameshughes1974
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    jameshughes1974 Member

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    Well I finally cracked the turbo open and even after shoving all sorts of oils and cleaners down it whilst on the bench it was still sooted up.
    But all that is secondary. The exhaust impeller and the variable vanes look like somebody shot them. Its stuffed. Must be high exhaust temp gases as there isnt enough play in it to have hit the case. Perhaps all the over boosting rasies the temp.
    Any how its ebay time for a good second hand one - will be taking it apart before fitting it
    #26
  27. dunk
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    dunk Member

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    mine dumped the boost (and made the noise) with the factory turbo, standard map and also remap

    the brand new turbo (not rebuild)is a hybrid for more power, so definately not sticky veins or operating mechanism

    had egr system checked out, but i do not have the egr delete so in theory it could still be that

    the hesitation is much more likely when its cold - the first pull-out into the road at moderate throttle for instance, but it can do it when hot as well. - totally unpredictable, and i cant do anything to 'make' it do it to demonstrate the problem either - we had to do a long drive with logging to capture the boost drop just once
    #27
  28. jameshughes1974
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    jameshughes1974 Member

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    Tried mine with a new standard turbo today
    No dump valve or scuttling noises on gear change throttle off and no dropping into limp mode - pulls like a train and a lot smoother all round.
    Havent noticed any hesitation.
    It will be up for sale very soon - not because of any get shut quick its fixed! but because i should of waited for the right A4 to come along £7500 if anybody is interested-bose and leather and electrics fully serviced 12month mot cambelt etc- sorry moderators bit of a plug there! dont shoot me!
    #28
  29. bugwhizz
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    bugwhizz Member

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    I've owned 3 cars to date with this engine in.
    1st Mk5 golf gttdi
    2nd A3 tdi QS
    3rd Chrysler Jeep Patriot

    Only on the 3rd car have i had this issue and i decided to dig into it today, first checking all vac connections and electrical plugs.

    whilst checking the vac connections i came across a vac pipe that came from the airbox and went to what can only be described as a vac control unit, there were 6 other vac pipes going into it and the one from the airbox had come adrift.

    I refitted the vac pipe into the rubber boot it came from and then re seated the actual vac connector, my car no longer stutters or hesitates.

    Might be worth you guys checking this vac control unit for vac pipes adrift, or a vac leak as thats basically what mine was.

    Good luck and happy hunting, oh and btw, the only reason i bought my wife the Jeep patriot was because it had a German engine in it LOL
    Last edited: Aug 25, 2012
    #29
  30. Cossie_boy
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    Cossie_boy Member

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    Bugwhizz, any chance of a photo?

    I have a hesitation but at higher revs in higher gears and have virtually elminated all options!
    #30
  31. theo289
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    theo289 Member

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    Hi all,

    i have this issue and have had it for well over four months! So far I've thrown over £1k getting the dealer to look at this, getting new parts on the car and so much more. I'm at the ends with the car and just unsure.

    Wasthis just the vac causing the issue? Where about is this vac?
    #31
  32. theo289
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    theo289 Member

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    Did you manage to resolve this? I have the same issue and keen on knowing what the underlying issue was?
    #32

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