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TDI help (but a newer engine)

Stuart B Jan 2, 2018

  1. Stuart B

    Stuart B Well-Known Member

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    Hi,

    So not a single reply from the 8P section (i cant believe it is too difficult for them) so I will try here just in case someone has an inclination?

    any ideas?

    upload_2018-1-2_19-11-35.png

    what I did notice is you cannot drive a TDI (CR110) with the N75 unplugged it goes into limp mode and the screen washer / wipe doesn't work.


    Thanks if anyone has an idea.
     
  2. Silva bullet

    Silva bullet Member

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    Check vacuum actuator located on the inlet manifold..
    If this is not right the car will go into limp mode.
    I'm sure some usual mechanic will step in and help you more lol
     
  3. Stuart B

    Stuart B Well-Known Member

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    I am totally out of my depth on this car - I have even ordered a new cable as a KKL Lead doesn't work on any VW / Audi's past 2006

    I don't like the idea of my son-in-law "rebooting" the car whilst driving with my grandkids in the back either I had to do this on a C200 a few years ago - picking a roundabout etc to reset out of limp mode.
     
  4. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow... Staff Member Moderator Audi S3

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  5. Stuart B

    Stuart B Well-Known Member

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    Thanks for a reply Tuffty I really appreciate it.

    Is the VNT the j883 exhaust flap pre-cat thing ?

    I'm wondering if this has been mapped somehow it's only supposed to be 110bhp but the android torque estimate is showing 120 bhp at the wheels? Do you know if the MAF divide by 0.8 is supposed to also apply to diesels ?

    I think this car is on a cross over of tech as well because they are supposed to be 5k but multiple parts are 1k - I think anyway.
     
  6. Alex C

    Alex C Well-Known Member VCDS Map User Audi S3

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    VNT is a variable nozzle turbo
     
  7. Stuart B

    Stuart B Well-Known Member

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    still none the wiser - it's not in the list of potential causes for the P0299


    I'm going to be :-

    1. using some Inlet, EGR + Turbo cleaner aerosol
    2. replacing Air filter
    3. replacing N75
    4. checking DV for perforated diaphragm
    5. checking J883 (if able to undo it) and lube up whatever the flap is
    6. scanning using VCDS (once the CAN cable arrives)

    gawd I hate cars
     
  8. Alex C

    Alex C Well-Known Member VCDS Map User Audi S3

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    apologies, turbo is the codeword for turbocharger; Variable Nozzle Turbocharger

    P0299:
    Possible Symptoms
    • Reduced Power Output
    • Limp Mode
    Possible Causes
    • Hoses/Pipes incorrect connected, disconnected or leaking
    • Charger Pressure Control defective
    • Turbocharger faulty
    • Diverter Valve faulty
    Possible Solutions
    • Check Hoses/Pipes to/between Components
    • Check / Clean / Replace Charge Pressure Control
    • Check Turbocharger
    • Check Diverter Valve
    Special Notes
    • If the Turbocharger is faulty due to mechanical / internal problems or the exhaust system is restricted (typically the Catalyst) this fault may be the end result.
     
  9. desertstorm

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

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    Calculating power from the MAF readings doesn't work with a diesel as there is so much excess air, and the Lambda values are completely different on a diesel.
    Low boost can be caused by a lot of different faults on a TDI engine.
    Some are relatively easy to check others more difficult.
    First check I would make is looking for a boost leak. You need to check all the intake hoses and the intercooler for any signs of a leak. There are usually oil wet patches where leaks occur as the crankcase fumes are blown through the intake system.
    Check all the vacuum lines that you can see whilst you are looking as well, especially around the N75 actuator.
    You can check the actual actuator itself by using a hand held vacuum pump or even just attaching a hose and sucking on it to make sure theres no hole in the diaphragm.
    This video shows the turbo VNT actuator. There is a metal vacuum connection on the side of the actuator that connects to a diaphragm inside that is what moves the VNT actuator rod. The electrical connector on the top is a position sensor so the ECU knows where the VNT actuator is .

    The diaphragm can split and the actuator then doesn't work correctly. If you attach a piece of vacuum pipe to the actuator directly and suck on it you should see the actuator move on the turbo and the diaphragm should hold the vacuum . If you have to keep sucking and it doesn't hold a vacuum then there is a hole in the diaphragm.
    If you have VCDS you can check the N75 on the output tests and listen for a leak.
     
    Alex C likes this.
  10. Stuart B

    Stuart B Well-Known Member

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    Thanks For some more help I have plenty of low impact tests to do at the weekend now :)

    Alex sorry - so I know what a turbo is I assume the VNT is just the type of Turbo - I thought it might have been some other device in the chain.

    is the actuator the dome on top of these turbos - that's also a common fault apparently.

    so VCDS also claims the J883 might also be faulty.

    Code:
    Diesel
    When found in VW Golf/Jetta (1K) 2.0l CR-TDI (CBEA/CJAA)
    Verify the mechanical part of the Exhaust Valve Control Module (J883) is not seized or binding.
    
    this is pre-cat - hopefully on a vband?

    thanks desert storm I can go through some of these tests.

    weird it only happens in 4th and 5th - must be load based - maybe it will get worse and start happening in 3rd next.
     
  11. desertstorm

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

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    In low gears when accelerating the ECU only sees the low boost condition for a short time as the car is accelerating a lot quicker. In higher gears under high load the low boost condition occurs for a much longer time so results in the fault code being logged.
     
  12. Stuart B

    Stuart B Well-Known Member

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    okay yes so that makes sense thanks, nothing to do with load just duration of the fault.
     
  13. Stuart B

    Stuart B Well-Known Member

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    replaced the N75 , and threw in a whole aerosol of EGR and intake cleaner and then half a can of turbo cleaner - that chucked out quite a bit of black smoke and was difficult to keep running. and replaced the air filter.

    ran the car around the block including a 4th gear long uphill run on turbo and didn't get another error (although the turbo boost only went to 14 PSI when it was 16 PSI the other day? maybe just different ambient temp and / or pressure (is it possible to get a different air pressure on a different day or is it always location based?)

    so far - no errors - they have a long run in a day or two so that will be the real test. would be fricken lucky if just those have fixed the problem but I suppose a miracle is possible.
     

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