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Turbo Wastegate "stuck"

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Chrisavant, Dec 13, 2009.

  1. Chrisavant
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    Chrisavant Member

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    [Dec 13, 2009]
    Hi guys,

    Can anyone advise on this problem. My 2.5TDi Multitronic is jerky at low speed just after moving off. At about 25 - 40 mph it again slightly jerks and squawks like a parrot. I feared Multitronic problems (as this was replaced 20,000 miles ago), but Audi have diagnosed that the turbo is effectively giving full boost all the time because the wastegate is not operating over its full range. So the poor old Multitronic is getting too much torque at too low revs, causing the clutches to slip and making squawking noise. If I drive in manual and make it rev a bit, the problem goes.

    Audi want an arm and leg to fix it. They say that the problem is caused by internal parts for the wastegate, and a new turbo is the only answer. They say that the manifolds will also require replacement because they start to flake internally, and this quickly ruins new turbos.

    I have had this car from new, and it has done a high mileage (185,000) but runs like a dream and still doesn't use any oil between approx 18,000 mile services. It seems a shame to scrap an otherwise lovely car, which is in excellent condition.

    Any advice would be much appreciated. Best regards, Chrisavant.:think:
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  3. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    [Dec 13, 2009]
    Why would you need to scrap it?

    A recon turbo at that sort of mileage can't be grumbled at, and a pair of exhaust manifolds wouldn't break the bank either. Get an independant to do the work and I would guess at £1k to 1.5k max?
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  4. kite
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    kite Member VCDS Map User

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    [Dec 14, 2009]
    I thought overboost would cause "limp mode".
    I would get it checked by another garage.
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  5. maz1975
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    maz1975 New Member

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    [Dec 14, 2009]
    Neah that wouldnt cause limp mode, I had the same problem, and had to have a new turbo fitted. Like you I found Audi were charging an arm and a leg, but managed to source a brand new one for less than half the price. The turbos are made by Garret, if I recall correctly and these can be sourced quite readily. I might be able to dig up the place I got mine from who were the cheapest at the time, I think I got it for around £500
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  6. demus
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    demus Fire in the hole !!

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    [Dec 14, 2009]
    The turbo vanes got all jammed on my TDi 130 a while ago, caused by a year of a **** drive to work every day I think and not being able to open it up.

    The problem manifested itself by making an awful noise through the air cleaner when you shut off the throttle, the vanes where where not returning from the boost position quick enough, eventually getting to the point where it needed a couple of miles to loosen them, then if when I did open it up, the vanes would get stuck wide open, and as the engine revs increased the vanes should normally back off slightly to regulate the boost pressure, but mine didnt and the car quickly went to limp mode.

    I fitted a recon turbo in the end for about £400 and touch wood has been fine since.

    Hope you get it sorted..
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  7. Chrisavant
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    Chrisavant Member

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    [Dec 15, 2009]
    Many thanks to you guys above. Most helpful and thank you for taking the trouble. I think I have finally convinced myself that its time for a new one - well not new in these economic times, but perhaps a two year old.

    I'm going to see if there's any interest in this one, which would suit a low mileage driver. I'll start a new thread with all the spec.

    Once again, many thanks.
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  8. NHN
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    NHN Retrofitter - Audi - VW - Skoda - Seat Site Sponsor VCDS Map User

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    [Dec 15, 2009]
    Maz no disrespect, but if what audi are saying is true, debatable, then of course if the turbo was running at full whack it would cause overboost with the wastegate issues, so limp mode would be enforced because the actual & specified boost that the ecu is detecting is so improperly balanced, so to protect the engine it backs the power of, commonly known as LIMP MODE

    Tbh mate I would get the turbo removed & recon'd which is cheapest option & as for mani, well inspection would be best to see if anythings going on as I am finding this hard to beleive, dealers get one car in with the issue & immediately assign all that chassis with the same fault, not to say yours isnt but before coughing up loads of dough, get it checked visually by a sensible garage with actual proper knowledge instead of speculative.

    Sticking vanes, if the impellor isnt damaged & no visual issues, can be resolved by cleaning up the turbo mate.
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  9. demus
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    demus Fire in the hole !!

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    [Dec 16, 2009]
    If you can get to the turbo, see what the actuator lever feels like to move by hand.. you should be able to move it about half an inch or so reasonably easily, if your not getting truck loads of blue smoke chances are the vanes are just sooted up and sticky..
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  10. NHN
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    NHN Retrofitter - Audi - VW - Skoda - Seat Site Sponsor VCDS Map User

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    [Dec 17, 2009]
    Yeap I'd agree with that, sometimes a temp fix would be to manually move the actuator lever many many times to try & moves the vanes & internals that would grind some of the **** of the moving parts, but as I said this is a quite literal temp attempt at a fix to just even get you to the garage safely, by no means is this a complete fix, not at all, when mine blew I took it apart & after seeing the prob I could have helped it by doing this, but alas we live & learn.
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  11. demus
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    demus Fire in the hole !!

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    [Dec 17, 2009]
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  12. davkav
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    davkav Member

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    [Dec 18, 2009]
    I had a similar problem on my old 1.9Tdi.

    Firstly your turbo doesn't have a waste gate it has vanes in the turbo that change there pitch to increase boost.

    Before I sorted the problem my car would constantly go into limp mode becuase of over boost isssues. The actuator rod would not budge when i tried to force it by hand also.

    I found a DIY on the net to take the turbo out, strip down and clean it all out. Now the car drives like a dream not a bother on here.

    The turbo is very basic and very easy to strip down. The hardest part is getting the bloody thing out.

    Ill try dig out the DIY and you can see what you think.

    Edit: Link
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  13. Chrisavant
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    Chrisavant Member

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    [Dec 18, 2009]
    I'm in awe of you guys. Thank you so much NHN, demus and davkav, and for the links you sent me. I am now convinced that this is the trouble with mine. On switching off the engine, I can hear the tubo gradually slowing down to a standstill several seconds afterwards just as it's always done, so I don't think there's anything wrong with the turbines. I think it's just the variable vanes actuating ring which is stuck and that a good clean up would sort it out just as you said NHN.

    This tallies with my driving pattern which is a steady level motorway cruise at 80 for about 50 minutes to work each day. So the actuator ring doesn't get much exercise, and the soot can form and stick it up.

    I have managed to get to the unit and the actuator rod feels quite stiff but I guess there a stiff spring insde the vacuum motor? I will disconnect the rod and then feel what it's like. I notice that with the engine off, the rod is fully extended, which I guess is minimum boost position, and when the engine is started the rod retracts and moves the actuator arm up to the little stop screw with the yellow sealing paint on it (which I assume is maximum boost?)

    Thanks for improving my education davkav and showing me that there is no wastegate. This is Audi bullshit baffling brains (successfuly unfortunately!) and I now think I'll have a go or at least try to see how difficult it is to get out.

    As you say NHN we live and learn, and thank you guys for so generously sharing your experince with me. I'll let you know how I get on.
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  14. adamss24
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    adamss24 Well-Known Member

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    [Dec 18, 2009]
    Chris, if the actuator is moving smoothly from max boost to min boost, then the turbocharger is ok and IF the fault codes point to an overboost problem i would look elsewhere ! I believe the speed sensor or the gearbox brain does not comunicate with the ECU properly thus jerking and the dealer is just trying to buy their way out of it by misdirecting you ! First, the manifolds are dear on their own and toghether with the turbo they will suggest you to scrap the car. Take the car for a second oppinion and make shure you get all the fault codes...These multitronics are the most unreliable gearboxes and they should not be fitted to a powerfull, torquey diesel. By the way, how long is the gearbox warranted(i assume you had the work done by the same dealer !) ?
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  15. Chrisavant
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    Chrisavant Member

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    [Dec 18, 2009]
    Hi Adam,
    I completely agree that the Multitronic is unsuitable for torquey diesels. The 2.5 TDi has more torque than the more powerful versions intoduced later. It tries to get away with it by using the control electonics to turn down the torque at likely overload parts of the range, but when this fails or the turbo actuator sticks, the Multitronic is overloaded. You might like to look at the bit I wrote in
    "Multitronic problems - big problems". Katherine B. thread on this forum which discusses why I have had THREE multitronics fitted in my car!

    Surely this cannot be a coincidence that they keep supplying **** transmissions to me? It must be a feature of this particular car and I now believe that there has been something wrong from new such that there has always been too much torque. This is bourne out by the fact that the rev counter never moved about much. The transmission never needed to "change down" because it had so much torque it could, in effect, accelerate in top gear. Audis lent to me during the numerous lengthy replacement sessions had lively rev counters which showed significantly increased engine revs (ie lower ratio) for acceleration, unlike mine.

    This latest Multitronic 20,000 miles now is gauranteed one year and was done last February. When the Turbo was diagnosed recently, I had them change the oil early (ie not 40,000) and they said it was dirty like 40,000 mile old oil would be. This means the clutches have been slipping and wearing colouring the oil.

    I couldn't say the turbo was moving smoothly from max boost to min boost. The lever appears to move over the full range in the engine off to engine running conditions, but if it is sluggish or sticking as demus noted above, it could cause this jerkiness.

    Since the "diagnosis" by Audi, I have been driving it in manual, thus holding a lower ratio for longer and reducing the need for torque which I feel is damaging the Multitronic. This does produce a much smoother flow of power, so maybe the stuck actuator or the gearbox brain / ECU theories are the answer.

    Many thanks for your valuable suggestion and I will also try this route
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  16. adamss24
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    adamss24 Well-Known Member

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    [Dec 19, 2009]
    Chris, if you get a cheap vag-com or VCDS lead get a diagnostic scan done and post the faults on the forum...i really want to see them faults. Also with vcds you can cycle the turbo's actuator(charge control valve as audi refers to) on and off and you can see how smooth it moves. I still believe there is a problem with the multitronic brain and nothing to do with the turbo. When the turbo has an overboost condition it puts the car in limp mode and you wont be able to climb a steep gradient or get over 60/80 Mph. When you said the oil has been replaced, you mean the gearbox oil not the engine oil, yes ? They dont share the same oil and for god sake dont keep engine oil for that long(i think you meant the multitronic box oil there !). The multitronic box comunicates with the ECU via the CanBus so if the box brain dont see the engine speed it will jerk. For the money you spent so far on multitronic gearboxes, i would have done a manual conversion and have none of the problems !
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  17. Chrisavant
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    Chrisavant Member

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    [Dec 19, 2009]
    Hi Adam,

    Thank you very much for your comments above. I haven't done much today as it is so cold, and I had to work outside as garage full of another project. However I have removed or moved a few bit and pieces so I could get a really good look at the actuator rod whilst I got the little woman to start and turn off the engine. On starting the rod withdraws into the actuator smoothly but relatively slowly, presumably as it takes a few moments for the vacuum to build up. On turning off, the rod extends quite smartly but again without any apparent snagging. It moves right up to the stop screw, and fully back as far as I can see.

    Yes, it was the Multitronic oil (ATF) I was referring to, as you guessed.

    I'm not really up to speed on the electronic diagnosis tools so I'm not sure what a vag-com or VCDS lead is. Presumably this is something which would plug into VAG cars and present the signals in suitable form for a standard diagnostic box, is it?

    If so, where can I get one, and then where do I take it to? Would this forum or say Yellow Pages advise me where there is a diagnostic centre? Wouldn't a diagnostic centre already have ne of these leads?

    I'm sorry to be so thick but this is a new area to me. Audi did say that previous tests hadn't shown overboost but now this was apparent. I begin to wonder if this was just to get them away from the cost of sorting my Multitronic if that is what it really is.

    Any help would be much appreciated. With hindsight (a wonderful thing) converting to manual would have been a much better idea!

    Thanks, Adam
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  18. BILKO1
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    BILKO1 Member

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    [Dec 19, 2009]
    You can get a VCDS off of NHN for a very good price you will need a laptop too. If you don't want to buy one then try the VCDS forum http://www.audi-sport.net/vb/showthread.php?t=84603 to see if any members are near you to do a scan for a few beer tokens.
    Last edited: Dec 19, 2009
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  19. NHN
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    NHN Retrofitter - Audi - VW - Skoda - Seat Site Sponsor VCDS Map User

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    [Dec 20, 2009]
    Thanks Bilko, yes Chris if interested in purchasing genuine vagcom, send me a PM please mate & dont worry its not that hard to use overall & you have us to assist you if you get stuck anywhere.
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  20. Chrisavant
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    Chrisavant Member

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    [Jan 13, 2010]
    Back on the case now after Christmas and the snow. Since last on here I have driven almost 2000 miles using manual, and have not experienced the dreaded limp mode (the car that is!). Have not got VCDS lead yet but have cycled the Turbo actuator as Adamss24 suggested, by simply pulling off the vacuum pipe with engine running and pushing back on. The actuator rod moves the lever apparently smoothly over the whole range, so I am becoming very suspiscious of what Audi told me. The gearbox grunts and grumbles a bit, driving like this, but nothing like as much as in auto mode where it is all torque and low revs. If I can get them I will report the faults on here and ask you to have a look at them Adamss24 if you wouldn't mind. Chris
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  21. Chrisavant
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    Chrisavant Member

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    [Jan 29, 2010]
    Hi adamss24 and NHN.

    Well, Adam, you were absolutely right - thank you very much for your suggestion. And thank you NHN for your pm offer for vagcom; much appreciated.

    In the end I chickened out of buying my own on the basis I'm a virgin at all this, and got Colin Hicks, Mobile VW / Audi Independant Technician, recommended in this forum, to look at it for me. No matter what we did to the car, standing starts, full throttle from medium speed etc, the turbo never once overboosted but was always within the design range.

    So you were correct adamss24. There is no overboost and all this stuff about new turbos and new manifolds is complete Audi main dealer bullshit. The problem is with the Multitronic or the controls as you said, and they simply don't want a warranty claim.

    So my next battle is with the Audi dealership to try to get them to honour their warranty. If they refuse, I feel a bit of legal may come on! I'll keep you posted as to how I get on. In the meantime, many thanks for your guidance on this.

    Best regards,

    Chris
    #20

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