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3.0tdi Cduc problem ( Please Help ).

Leighspain1975 Apr 8, 2019

  1. Leighspain1975

    Leighspain1975 Member

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    hi guys

    Had this intermittent problem for about a year or so.

    Symptoms
    Car runs ok but sounds a bit rough like it’s struggling a little.
    Engine sounds louder than normal and injectors can be heard rebounding off walls when accelerating. Power seems slightly down. Slight judder on idle and judder when switched off.

    However....once every ten starts or so car runs like a dream, engine refined loads of pull and no shudder or injector noise. I can then switch of the engine and back to the rough running again. Doesn’t matter if hot or cold will just start perfect or rough.

    Things done and changed

    Vcds .... No errors what so ever car is clean as a whistle.
    Changed for new injectors
    Had Egr remapped and deleted
    Dpf is fine

    Problems occurred before and after above was changed.

    It almost feels like an air restriction because it’s definitely over fueling as I can hear the injectors ticking loudly outside the car.

    Thinking what about the ASV not opening properly sometimes and blocking air flow ?. But surely and error would trigger on vcds ?.

    Cheers
     
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  3. desertstorm

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

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    Have you tried logging some of the engine parameters on VCDS to see whats different between the time it's good and the time it's bad?. Sounds like the engine is doing a regen most of the time . Where abouts are you in the country?
    @bobby singh what do you think?
     
  4. Leighspain1975

    Leighspain1975 Member

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    Huge thanks for coming back to me desertstorm...

    Yeah I need to do some logging otherwise I’ll be spending a fortune in replacing sensors etc.
    What’s the best parameters to log?. I’m using vcds and Ecu is UDS protocol.

    Funny you should mention DPF regen.
    I have noticed the reverse. When the DPF does a regen the car runs much better. How weird is that ?.
    The engine suddenly silences, the injectors go quiet and it pulls like a train. If I switch of the engine at this moment I can hear the fans going as it’s not finished the regen procedure.

    Cheers for your help much appreciated
     
  5. bobby singh

    bobby singh BSR VCDS Map User TDi Audi A4 quattro

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    Try stock map. On some of these ECU’s the egr and dpf off is done hand in hand to prevent these issues.

    Is the egr blocked off or just turned off via software?
     
  6. Leighspain1975

    Leighspain1975 Member

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    Hi Bobby Singh

    Egr deleted by software only and Dpf still functioning as normal.
    Only deleted the Egr a week or so ago to see if this caused the problem but to no joy.
    I did blank the Egr too but the engine wasn’t happy at all so removed it.
    Remapper at ATM said the Egr will have some function to allow the Dpf to regenerate ( not sure how true that is ).
    I forced a Dpf regen yesterday and has minimal calculated soot.

    Some of the symptoms when running bad
    1. Very slight vibration at idle
    2. Vibration when switched off
    3. Low diesel clatter at low rpm
    4. Engine noise louder than normal
    5. Injectors (pinging ? ) can be heard like loud sewing machines bouncing of buildings.
    6. Slightly under powered when accelerating hard

    Suddenly car will change engine noise will go quiet and accelerate super smooth with no vibrations at all. It will do this intermittently cold or hot but always seems to smooth out after a really long run.

    Same effect will happen when the DPF is regenerating. Engine will suddenly go smooth as silk accelerate well with no injector noise.

    Audi kept it for a week and their final verdict was theirs nothing wrong with it. It’s just the kms it has and the age it has. No faults on vcds. Drives me nuts cause I know it drives better than they say.

    Thanks for you help
     
  7. Leighspain1975

    Leighspain1975 Member

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    Forgot to mention....

    When it was at Audi I asked them to revert everything back to stock. Didn’t help unfortunately.
     
  8. bobby singh

    bobby singh BSR VCDS Map User TDi Audi A4 quattro

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    With vcds post log of calculated soot, rpm, measured soot and dpf back pressure.

    Log in 3rd from 1.5k to 4k
     
  9. Leighspain1975

    Leighspain1975 Member

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    Will do...

    What should I expect to see if all is well ?.

    Do you mean 3rd gear between 1.5-4K rpm?.
    ( just checking ).

    Cheers
     
  10. Paul battams

    Paul battams Active Member VCDS Map User

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    3rd pull flat to floor I would think


    Sent from my iPhone using Tapatalk
     
    bobby singh and Gazwould like this.
  11. Leighspain1975

    Leighspain1975 Member

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    Hi Guys
    I did some logging with VCDS I didnt copy/paste the entire thing thought would share the highlights.

    3rd gear pull (stronic manual mode )....

    Rpm. Diff pressure. Cal soot. Meas soot.
    770. 8mb 0,45g. 10.55g
    1500. 45mb. 0,48g. 10.56g
    4000. 179mb. 0,50g. 10.86g
    3000. 70mb. 0,50g. 10,86g
    1800. 40mb. 0,50g. 11g

    Did a couple of runs and was consistently the same except for the measured soot increasing slightly more.
    Hope this helps ?.
    Thanks for your help
     
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  13. bobby singh

    bobby singh BSR VCDS Map User TDi Audi A4 quattro

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    Could you post the full description of this diff pressure label?

    180mbar back pressure is normal.
    Maybe include the actual boost value too.

    Cheers
     
  14. bobby singh

    bobby singh BSR VCDS Map User TDi Audi A4 quattro

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    The only thing that sticks out for me so far is blocking the egr with a plate caused more issues. If the egr is off in software then blocking the egr should not make any difference.

    I would ask your tuner to locate a known stock map file for your car and write that.
    I’ve seen some cars with strange issues only to find the previous owner has had the error codes deleted from the file. So you wouldn’t even know.

    However, you mentioned Audi already tried this?
     
  15. Leighspain1975

    Leighspain1975 Member

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    Hi Bobby Singh

    Yes, I took to Audi with the hope of resetting the ECU would cure the problem. I had another remap from another tuner previously thinking it was bad. Audi made everything stock for me. Well they actually only reset the Stronic but they said this will reset the engine too?.

    Everything did seem much slower after that I have to admit. Still had the same problem so I took it to ATM for another tune which was definitely a better tune but still had the same problem.

    Such a shame because when the car is smooth it’s wonderful to drive but when it’s rough it’s awful especially in slow traffic and city driving. Don’t notice so much in WOT but definitely lacks power higher up too.
     
  16. Leighspain1975

    Leighspain1975 Member

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    Do you think it could be a fueling issue?.

    I’ve had new injectors and problem remained . New fuel filter too.

    Maybe I should log fuel pressure when driving?. At idle fuel pressure is spot on.
     
  17. bobby singh

    bobby singh BSR VCDS Map User TDi Audi A4 quattro

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    @Leighspain1975

    Are you local to Heathrow? If so drop me a message. Once I see it I’ll be able to better help you.

    Resetting adaption for gearbox has nothing to do with putting stock map flash on the ecu. Im not sure what Audi is talking about tbh.

    Cheers
     
  18. Leighspain1975

    Leighspain1975 Member

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    Cheers for your help.

    I asked the last tuner to check that the “Stock” map he saved is in fact stock. If not I’ll drop it back to Audi and get it flashed to factory settings. Can only imagine how many errors may or may not show up.

    Literally had another symptom this morning. Started the car and the engine was pulsating. Rev counting wasn’t moving but could hear the clattery diesel sound or injectors pulsating.
    Suddenly the clatter sound made a noise I can only describe is when you fill a bottle to the brim with water and makes that noise that gets higher pitched until full. Once it did this the motor smoothed out. Well still rough but smoother than before.

    Could that noise be the egr closing or opening making this type of noise?.
     
  19. Leighspain1975

    Leighspain1975 Member

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    Hi Bobby Singh

    I’m starting to have a big suspicion of the EGR valve playing up.
    It is definitely something that could cause intermittent problems like this.

    But if I blanked it off shouldn’t the engine have suddenly run better ?.
    The strange thing is that when I blanked it off the MAF reading went through the roof. Surely that shouldn’t happen if it’s deleted by software?.
     
  20. Leighspain1975

    Leighspain1975 Member

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    Hi

    When I blanked the EGR I put the plate at the blue circle in the attached image. I assume the best place is at the turbo.
    Would this make any difference as to where I installed the blanking Plate ?.
     

    Attached Files:

  21. bobby singh

    bobby singh BSR VCDS Map User TDi Audi A4 quattro

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    You can block it post or pre egr doesn’t matter too much.
    I normally just make a plate for the inlet manifold side as its easy access.

    Once blocked off the engine should run fine and no errors are normally shown if egr is off via software. I have most of the stock files for all VAG’s if your tuner doesn’t have it.

    Follow this guide to get the software id and I’ll get it for you or like i said drop me a pm and i can take a look etc

    https://store.034motorsport.com/checking-ecu-tcu-box-code-software-version-audi-volkswagen/
     
  22. Leighspain1975

    Leighspain1975 Member

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    Cheers Bobby Singh

    What other Logs can I check to solve this problem. I need to log when good and again when bad and compare the two.

    Definitely not the EGR unplugged it today. Car ran rough for about 8 starts and then 9th start as smooth as silk. Switched off again and rough again.
     
  23. bobby singh

    bobby singh BSR VCDS Map User TDi Audi A4 quattro

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    You sure the replacement injectors that were installed have the correct coding done for them?
     
  24. Leighspain1975

    Leighspain1975 Member

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    Hi

    Yeah injectors are fine.
    Had them fitted by Bosch service and have checked the codes of VCDS and the codes on each injector.

    What about the Egr solenoid ?.
    The one that powers the egr cooler valve by vacuum.
    Could this have the same symptoms ?.
     
  25. Leighspain1975

    Leighspain1975 Member

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    Hi Guys

    Is this normal ?.
    Used my OBD eleven to check Air mass flow.
    This is a screenshot during deceleration from a 3rd gear pull.
    Why is the specified value staying at 1500mg/s and not dropping ?.
    Should the actual be following this ?.



    B3E0EAA4-31D6-4761-BBF0-9ABBF3EB78A9.jpeg 5342EAEF-BA56-40E2-B677-4878D09474A8.jpeg
     
  26. Leighspain1975

    Leighspain1975 Member

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    Here’s a log of the actual acceleration and deceleration. Decelerating starts when Maf spec peaks at 1500 mg/s


    Time. Maf.Act. Maf.Specified
    31956 752.1 766.9
    32091 756.3 778.2
    32202 784.6 786.0
    32265 792.2 788.4
    32332 796.7 789.5
    32394 794.9 792.8
    32466 795.8 821.0
    32542 791.5 836.1
    32622 806.1 842.6
    32692 825.3 852.1
    32772 831.8 862.4
    32845 837.5 869.5
    32913 843.8 874.8
    33015 849.8 883.2
    33086 845.0 896.6
    33165 843.7 905.7
    33242 838.9 912.9
    33314 833.3 915.8
    33384 826.1 919.8
    33471 820.6 924.4
    33546 817.3 925.7
    33613 814.8 927.7
    33683 809.1 933.7
    33755 806.3 935.2
    33834 802.2 966.2
    33903 798.5 1021.1
    33970 795.6 1135.0
    34034 795.1 1282.1
    34204 825.4 1500.0
    34293 909.3 1500.0
    34364 977.5 1500.0
    34433 1054.1 1500.0
    34513 1119.7 1500.0
    34583 1176.9 1500.0
    34652 1251.3 1500.0
    34732 1328.8 1500.0
    34804 1381.4 1500.0
    34875 1378.4 1500.0
    34953 1311.6 1500.0
    35023 1201.0 1500.0
    35086 1182.4 1500.0
    35271 1195.5 1500.0
    35346 1175.7 1500.0
    35422 1177.4 1500.0
    35525 1186.9 1500.0
    35595 1189.4 1500.0
    35674 1194.3 1500.0
    35753 1192.9 1500.0
    35823 1189.6 1500.0
    35883 1189.1 1500.0
    35969 1196.7 1500.0
    36045 1195.7 1500.0
    36110 1200.0 1500.0
    36173 1201.8 1500.0
    36242 1203.1 1500.0
    36309 1204.2 1500.0
    36373 1211.2 1500.0
    36456 1215.5 1500.0
    36533 1214.5 1500.0
    36602 1212.4 1500.0
    36674 1204.2 1500.0
    36762 1195.2 1500.0
    36833 1181.5 1500.0
    36912 1173.2 1500.0
    36972 1160.6 1500.0
    37043 1152.9 1500.0
    37112 1146.1 1500.0
    37185 1147.9 1500.0
    37254 1140.7 1500.0
    37324 1119.6 1500.0
    37392 1118.1 1500.0
    37455 1135.5 1500.0
    37540 1068.7 1500.0
    37605 976.7 1500.0
    37677 921.8 1500.0
    37755 881.1 1500.0
    37824 847.2 1500.0
    37902 811.3 1500.0
    37984 765.0 1500.0
    38053 776.0 1500.0
    38125 794.1 1500.0
    38203 790.6 1500.0
    38356 799.2 1500.0
    38460 802.0 1500.0
    38535 800.6 1500.0
    38602 793.5 1500.0
    38674 791.2 1500.0
    38743 785.2 1500.0
    38808 787.5 1500.0
    38874 782.4 1500.0
    38950 779.3 1500.0
    39026 781.3 1500.0
    39157 780.5 1500.0
    39342 773.6 1500.0
    39423 768.8 1500.0
    39494 765.9 1500.0
    39565 762.0 1500.0
    39633 760.7 1500.0
    39695 760.0 1500.0
    39775 757.6 1500.0
    39842 759.5 1500.0
    39913 758.4 1500.0
    39986 758.3 1500.0
    40053 758.2 1500.0
    40131 756.0 1500.0
    40202 755.8 1500.0
    40272 753.0 1500.0
    40344 753.6 1500.0
    40413 752.0 1500.0
    40507 751.2 1500.0
    40583 747.7 1500.0
    40652 745.9 1500.0
    40722 742.8 1500.0
    40785 742.9 1500.0
    40853 741.9 1500.0
    40932 741.1 1500.0
    41003 739.0 1500.0
    41081 739.8 1500.0
    41145 738.5 1500.0
    41225 736.5 1500.0
    41314 738.7 1500.0
    41450 736.6 1500.0
    41552 735.9 1500.0
    41614 735.2 1500.0
    41696 735.6 1500.0
    41771 733.5 1500.0
    41839 733.5 1500.0
    41902 734.5 1500.0
    41972 738.4 1500.0
    42045 737.4 1500.0
    42125 735.2 1500.0
    42194 732.6 1500.0
    42266 738.4 1500.0
    42340 741.3 1500.0
    42418 737.5 1500.0
    42484 737.3 1500.0
    42572 737.6 1500.0
    42637 737.4 1500.0
    42705 737.6 1500.0
    42784 736.7 1500.0
    42862 739.3 1500.0
    42947 737.8 1500.0
    43013 738.1 1500.0
    43084 737.4 1500.0
    43153 738.9 1500.0
    43223 739.5 1500.0
    43292 739.0 1500.0
    43363 742.2 1500.0
    43423 737.2 1500.0
    43504 734.9 1500.0
    43587 738.4 1500.0
    43662 737.0 1500.0
    43735 736.6 1500.0
    43813 738.1 1500.0
    43873 738.9 1500.0
    43942 735.4 1500.0
    44003 737.2 1500.0
    44072 733.7 1500.0
    44160 732.5 1500.0
    44224 734.6 1500.0
    44311 733.5 1500.0
    44383 733.0 1500.0
    44471 732.5 1500.0
    44623 730.0 1500.0
    44696 730.3 1500.0
    44771 728.3 1500.0
    44843 728.3 1500.0
    44934 729.5 1500.0
    45005 726.8 1500.0
    45076 725.9 1500.0
    45162 725.0 1500.0
    45233 722.4 1500.0
    45303 721.8 1500.0
    45372 722.7 1500.0
    45463 718.9 1500.0
    45533 719.6 1500.0
    45602 716.9 1500.0
    45664 717.9 1500.0
    45742 719.6 1500.0
    45812 716.3 1500.0
    45883 716.3 1500.0
    45953 713.4 1500.0
    46023 713.2 1500.0
    46082 708.1 1500.0
    46162 708.5 1500.0
    46232 708.0 1500.0
    46293 704.9 1500.0
    46362 703.1 1500.0
    46424 703.8 1500.0
    46502 704.5 1500.0
    46573 700.0 1500.0
    46673 700.4 1500.0
    46744 699.9 1500.0
    46822 697.4 1500.0
    46893 696.2 1500.0
    46976 697.4 1500.0
    47044 694.8 1500.0
    47132 694.3 1500.0
    47203 696.3 1500.0
    47283 693.7 1500.0
    47374 692.0 1500.0
    47447 692.3 1500.0
    47523 689.8 1500.0
    47631 689.2 1500.0
    47782 687.1 1500.0
    47844 686.8 1500.0
    47942 687.9 1500.0
    48013 685.5 1500.0
    48085 684.7 1500.0
    48154 682.6 1500.0
    48227 682.1 1500.0
    48300 681.3 1500.0
    48373 681.4 1500.0
    48446 678.0 1496.7
    48525 679.2 1445.1
    48598 677.6 1405.7
    48662 675.3 1359.0
    48732 674.4 1324.5
    48802 675.5 1277.8
    48882 673.7 1245.8
    48955 670.6 1208.9
    49026 669.4 1149.9
    49093 670.0 1142.5
    49172 668.2 1068.7
    49252 668.0 1024.4
    49326 668.3 987.5
    49403 668.9 933.4
    49464 670.5 886.7
    49534 668.9 871.9
    49622 666.2 820.2
    49688 664.1 785.6
    49772 665.7 781.8
    49832 665.7 781.6
    49904 666.2 779.1
    49993 666.7 776.8
     
  27. Leighspain1975

    Leighspain1975 Member

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    Hi Bobby Singh

    Possible Breakthrough ?.

    So I’ve been with this ****** car all day long.starting and stopping the engine until I hit the sweet spot and the engine runs Smooth. So was about 15 rough starts engine sounds louder than normal and car is vibrating a little.
    After the 15th time I switched off the engine and locked the doors.

    I then opened the door and the fuel tank fuel pump that normal makes a noise actually made what I can imagine as a much stronger noise. I also heard a pump or something under the bonnet making a whiring noise too. I then started the engine and Boom smooth as silk engine was super quiet and no vibrations at all. Engine seemed happy and under no stress.
    This continued for 4 starts and then boom rough again. Now it could be my imagination but the pump priming sounds different like it’s a little weaker. Can’t really explain it. Also no whiring noise happened under the bonnet either which I can imagine is normally the HPFP?.

    Do you think I can have an intermittent problem with either the fuel tank pump or the HPFP ?.
    Can’t find anything on vcds that can check either pump in adv measuring blocks.
    Just wanted a second opinion before slashing out for new pumps.

    I did some other checks while engine was smooth at idle and this is what I had...

    Idle RPM : 700
    Maf : 340mg/s
    Egr duty cycle : 99.9% ( closed )
    O2 sensor : 0.345 Lambda / 1001 mv

    All six injectors ( deviation within range )
    Between -25 to 0,65

    Cheers for your help
     
  28. Leighspain1975

    Leighspain1975 Member

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    Hi All

    So I took her out again today and from the moment the engine turned over to start I knew it would be smooth. It was perfect no vibrations at all at idle, gears changing more smoothly than normal ( weird ) and the engine was most silent I’ve ever heard since owning the car. You wouldn’t even know it’s a diesel. The acceleration and power was full and I knew this cause I only have to feather the throttle when it’s like this and she pulls hard.

    I assumed it was regenerating because it was smoother than normal and no clatter.

    I parked up for an hour or so and started the car again still smooth as silk. But after driving for about 10 mins boom, starts to feel rough again smoothness has gone and engine clattering away again.
    I also think I could smell diesel but not sure if it was something else.

    I’m starting to think either the LPFP or HPFP could be a fault here ?. It definitely seems like the engine is starving of something and is not happy for sure. But could either of these pumps have intermittent problems like mine and why don’t they trigger a fault code ?.

    I inspected behind the HPFP and near where the cam shaft would connect to the engine it seems a little wet?. Think it may be oil ?.

    Also when opening the door again with engine off the pump wasn’t making a strong priming sound as it did when smooth.

    Im a bit confused though. Would the actual and specified fuel pressure values be off if it was a pump issue ?. Because they are always spot on whether car is smooth or rough ?.

    Could the HPFP be working too hard to draw pressure from the LPFP?.

    Any help would be great

    Cheers
     
  29. bobby singh

    bobby singh BSR VCDS Map User TDi Audi A4 quattro

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    Normally HPFP will throw a rail pressure dtc if faulty.
     
  30. Leighspain1975

    Leighspain1975 Member

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    Huge thanks for getting back to me Bobbysingh and really appreciate your help with this.

    Agreed Re: Rail pressure would throw a code. And after logging it’s almost spot on with specified except for a couple of bar difference.

    Did those MAF figures posted earlier look healthy to you ?.
    Just thought it was weird specified was so high on deceleration ?.

    The problem I have must be mechanical and that’s why no sensors are picking it up. One thing, I’ve had a metallic rattle for ages and thought it was the engine. But when I turn the AC on and off it goes. Could I have a load issue with the AC?. I mean putting extra load on the engine ?.
     
  31. bobby singh

    bobby singh BSR VCDS Map User TDi Audi A4 quattro

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    You sure its not a Aux belt tensionor?
    To be honest I need to see the car to see exactly what the problem is and find the root cause.
    Doing this via posts is too time consuming with no real results.

    Feel free to drop me a email - BobbySinghRacing@outlook.com

    Cheers
     

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