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Eliminate diesel clatter CDUC, CDUD 3.0tdi

Leighspain1975 Nov 4, 2018

  1. Leighspain1975

    Leighspain1975 Member

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    Hi All
    Thought I’d share this with you in case it helps someone......
    Has any 3.0tdi CDUC, CDUD owners who have higher mileage engines notice a more pronounced diesel clatter noise at idle or at low rpm and maybe notice the engine isn’t quite as smooth in low rpm as it used to be ?.
    Here may be your solution?.

    I was desperate to find the solution to this issue and did everything, new injectors, Maf, egr and Dpf cleaning. None of these really worked and it annoyed me that such a nice engine wasn’t as refined as it should be.

    By pure fluke I found the answer in 2 words “Swirl Flap”.....

    Bear in mind that the older 3.0tdi engines has swirl flaps in the intake manifold. The 2nd gen engines don’t. It has one large motorised swirl flap before the manifold with two holes. One for EGR return and other for fresh air. The fresh air hole has a butterfly valve which opens and closes but mainly it’s a low rpm when it’s used to swirl the air into the intake.
    These things fail and can do so without any warning light or error codes. The flap which gets built up with carbon may not be opening properly literally starving the engine of fresh air and too much EGR gases.

    Quick solution is remove the part and remove the butterfly valve, it’s only two screws and the rod can be left in situ so no error codes are thrown when plugged back in.

    Before removing the butterfly valve you can make a quick test. Unlock car open the bonnet, close the door and lock the car. Leave for a minute and disconnect the sensor/motor. The flap will now be fully open and you can test for yourselves if it improves the drivability of the car. It will eventually throw an error code and your Dpf may not regen as a result so if it’s improved I would suggest you remove the butterfly valve.

    You may notice at first that the car pulls away a bit more sluggish than normal but the ecu will rectify this after a few 100kms.

    The second part was to connect VCDS....
    Go to Engine - Adaptation - EGR Correction

    Select 35 mg/stroke as new value. Old value should be 0mg/stroke. This will close the EGR valve more and effectively tells the Maf to read higher fresh air intake you will probably see around 350mg/ stroke at idle with this adaptation. It’s within the parameters of the ECU so no harm will be done.

    Guys give it a try if you think your engine is sounding a bit clattery.
    Would be good to get some feedback if you try this yourselves.

    Cheers
     
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  3. Daniel J.

    Daniel J. New Member

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    I will try this weekend :) My CDUC behaves kinda clattery in cold weather these days, in low RPM and kinda low demands of power. I will report :) First I thought it could be bad DMF, but I have not found a single thread about anyone having a DMF worn out on these newer 3.0 TDIs, mine is only around 70k miles… And this actually makes sense.
     
  4. Leighspain1975

    Leighspain1975 Member

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    Yeah,
    Mines be fine since. Wouldn’t say any increase in power but the engine definitely sounds more refined.
    Remember when you do it.... the butterfly will naturally be half open when the engine is off and you can’t get to the screws.
    Disconnect first and then plug in and switch on ignition. The butterfly will move to a closed position and you can then get to the screws.
    Don’t force the butterfly.

    Cheers
     
  5. Daniel J.

    Daniel J. New Member

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    IMG_5753.JPG

    Hi,

    I will ask additional questions, I am not native so I need to make sure I understood your description. In the attached Picture - is the description ok? Is the part on the left the motorised swirl flap thing? If so, to test it, I should disconnect the connector on the side of it? If so, I would like to first test it out. So the procedure should be - unlock the car, open the bonnet, close doors, lock the car, wait a few minutes, disconnect the connector on the side of swirl flap housing, start the car and try out? What does not make sense, since you mention the natural position is half open, how can it fully open when disconnected?

    If the test will be ok, the ride improves, then I should remove the black tuby thing and unscrew the flap plate on two screws, let the rod there and connect the housing to the connector again?

    Sorry again :)

    Thank you,

    DJ
     
  6. Leighspain1975

    Leighspain1975 Member

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    Exactly correct

    Unlock car, open Bonnet ( Hood ) , close door, lock car, wait a few mins and the. Disconnect.

    Remember.
    Half open is actually fully open. The flap will rotate 90 degrees to fully open position. So the flap will be horizontal and letting full air into the car.

    If you decide to remove completely you’ll need to do what I said before. But the testing is very easy to do first.

    Let me know the results

    Thanks
     
  7. Daniel J.

    Daniel J. New Member

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    Ah, fine. I thought half open means like 45 degrees. This explains everything.

    This actually looks pretty damn easy.
     
  8. Leighspain1975

    Leighspain1975 Member

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    Yeah it’s a piece of cake to try it out.

    Drive the car a little while too to allow the fuel / air adjustments to take place too. It may start a little lazy but while suddenly pick up and run much better.

    I also find the engine idles much better too. The engine sounds more happy.
     
  9. Rhyso

    Rhyso Well-Known Member

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    [​IMG]

    [​IMG]
     
  10. Leighspain1975

    Leighspain1975 Member

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    Mine looked the same. Filthy and clogged but I think the motor in mine wasn’t opening properly either.
    Amazing to think all this filth comes from the Egr return.

    I have closed my EGR to minimal allowable settings.

    Vcds UDS protocol ....

    Select Engine, Adaptations, EGR Correction. Should be at 0.0mg reduced mine to -50mg
     
  11. Rhyso

    Rhyso Well-Known Member

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    Mine is mapped out via my remap :D
     
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  13. desertstorm

    desertstorm Moderator Staff Member Moderator VCDS Map User TDi Audi A4 Audi Avant Owner Group quattro

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    Makes you wonder why they bother with an air filter TBH when they are recirculating so much stuff back into the engine.
     
  14. Leighspain1975

    Leighspain1975 Member

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    Why would mine better when the DPF is regenerating?.
    I know it’s doing it because the fans switch on.
    It’s such a big difference too the engine will run quieter, be more responsive and it’s so much smoother.

    Can’t figure it out
     
  15. Leighspain1975

    Leighspain1975 Member

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    After the regeneration it goes back to its noisy bumpy self ?.
     
  16. Daniel J.

    Daniel J. New Member

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    Hi guys!

    So I tested it out (disconnected the connector, drive around for like 40 miles), I did not notice any difference, so I decided to let it be. I did not even disassamble the intake to clean it, I felt like too lazy this weekend :D

    But thank you for advice anyway!

    DJ
     

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