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Thread: Audi Q7 (V8 TDI) DPF measuring blocks

  1. #11
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    Good morning Gents.

    Im pleased to report that I have been able to access the measuring blocks for my dpf parameters in engine module #2 (as advised by Uwe yesterday) Results below:

    Code:
    Tuesday,26,November,2019,11:01:58:21534
    VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x64
    VCDS Version: 19.6.2.0 (x64)  HEX-V2 CB: 0.4508.4
    Data version: 20190930 DS308.0
    www.Ross-Tech.com
    
    
    VIN:    License Plate: OE07NKL
    Mileage: 189306   Repair Order: 
    
    
                    Address 11: Engine II  (4L0 910 409 )
    
    11:01:38 Group 102         (EXHAUST GAS CLEANING BANK 1)
      899.0C  Temperature     (Egt after pre cat)
      121.8C  Temperature     (EGT BEFORE DPF)
      0 mbar  Pressure         (pressure difference accross dpf)
      0 mbar  Pressure         (differential pressure sensor offset)
    
    11:01:38 Group 103         (EXHAUST GAS CLEANING BANK 2)
      899.0C  Temperature 
      121.8C  Temperature 
      0 mbar  Pressure 
      0 mbar  Pressure 
    
    11:01:38 Group 003
      693 /min  RPM                   (*****idle)
      276.1 mg/str  Mass Air / Rev. 
      487.6 mg/str  Mass Air / Rev. 
      464.1 mg/str  Mass Air / Rev. 
    
    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------
    
    
                    Address 11: Engine II  (4L0 910 409 )
    
    11:02:41 Group 105          (PARTICULATE FILTER BANK 1)
      0.20  (no units)          (oil ash volume)
      37.0  (no units)          (soot mass calculated
      6.5  (no units)           (soot mass actual/measured
      1340 km  Mileage          (distance since last regen)
    
    11:02:41 Group 106          (PARTICULATE FILTER BANK 2)
      0.20  (no units) 
      35.5  (no units) 
      11.5  (no units) 
      1340 km  Mileage 
    
    11:02:41 Group 003
      672 /min  RPM                  (******IDLE)
      282.0 mg/str  Mass Air / Rev. 
      270.3 mg/str  Mass Air / Rev. 
      293.8 mg/str  Mass Air / Rev. 
    
    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------
    
    
                    Address 11: Engine II  (4L0 910 409 )
    
    11:03:27 Group 102                  (**** AS ABOVE
      899.0C  Temperature             
      121.8C  Temperature 
      29 mbar  Pressure 
      0 mbar  Pressure 
    
    11:03:27 Group 103
      899.0C  Temperature 
      127.6C  Temperature 
      29 mbar  Pressure 
      0 mbar  Pressure 
    
    11:03:27 Group 003
      2331 /min  RPM                    (******* 2300RPM)
      640.4 mg/str  Mass Air / Rev. 
      564.0 mg/str  Mass Air / Rev. 
      475.9 mg/str  Mass Air / Rev. 
    
    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------
    
    
                    Address 11: Engine II  (4L0 910 409 )
    
    11:04:53 Group 105                     (****** AS ABOVE
      0.20  (no units) 
      37.0  (no units) 
      7.0  (no units) 
      1340 km  Mileage 
    
    11:04:53 Group 106
      0.20  (no units) 
      35.5  (no units) 
      11.5  (no units) 
      1340 km  Mileage 
    
    11:04:53 Group 003
      2394 /min  RPM                       (***** 2300RPM)
      522.9 mg/str  Mass Air / Rev. 
      605.1 mg/str  Mass Air / Rev. 
      517.0 mg/str  Mass Air / Rev.
    The first set of numbers are from the car sitting with engine at idle. The second set of numbers is with the car sitting with engine rpm at around 2300rpm.

    Im no expert but these figures all look reasonable to me. Also Both banks seem to be very similar. (i.e. not just one blocked dpf.)

    One thing that does look odd to me is the EGT after pre-cat readings. Are they high? Both sensors seem to be stuck at 899 degrees and don't move as if the had failed to max or something?? Just to satisfy my curiosity on this I have just left the car for an hour so its cold and plugged vcds in again. Without starting the engine (static) both EGT after pre-cat sensor readings are still maxed out at 899 degrees.

    I checked and there are no still no fault codes in engine module #1 0r #2. (other than cyl 4 glow plug) The car still has a permanent DPF warning on the instrument cluster which wont clear from driving.

    Any input/advice much appreciated.

    Regards, Ben.
    Last edited by Dana; 11-26-2019 at 09:35 AM. Reason: added the / in last [/code] tag

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  3. #12
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    Quote Originally Posted by benr8440667 View Post
    I have a glow plug fault code. Could this be stopping the car from automatically cleaning the dpf, and thus caused the problem??
    Normally yes, I would fix it.

    Quote Originally Posted by benr8440667 View Post
    One thing that does look odd to me is the EGT after pre-cat readings. Are they high? Both sensors seem to be stuck at 899 degrees
    Normally not installed.

    Quote Originally Posted by benr8440667 View Post
    The car still has a permanent DPF warning on the instrument cluster which wont clear from driving.
    Have you checked car user manual, it is described what to do, drive vehicle with conditions for regeneration.
    That should be possible if no sensor signals (eg glow plug) are faulty.

    I would make Controller Map files with diff. condition, idle, etc.
    [Applications]
    [Controller Channel Map]
    - Controller Address = 01
    - Login or security code: Leave blank
    - Function: Measuring values
    - Output: CSV file
    [Go]

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  5. #13
    VCDS Distributor AIB Wolfgang's Avatar
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    Hello Ben
    11:03:27 Group 103
    899.0C Temperature Exhaust gas temperature after precatalyst bank 2
    Idling: 90 ... 270 C
    At full load: 490 ... 830 C Temperature too high sensor or wiring faulty
    127.6C Temperature Exhaust gas temperature before particle filter bank 2
    Idling: 70 ... 250 C
    At full load: 490 ... 830 C
    29 mbar Pressure Differential pressure particle filter bank 2
    0 ... 950 mbar
    0 mbar Pressure Offset differential pressure particle filter bank 2
    -Wolfgang

    Drive more talk less

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  7. #14
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by AIB Wolfgang View Post
    11:03:27 Group 103
    899.0C Temperature Exhaust gas temperature after precatalyst bank 2
    Idling: 90 ... 270 C
    At full load: 490 ... 830 C Temperature too high sensor or wiring faulty
    Since both banks read the same, I'm inclined to think Niels is correct, that these sensors don't exist in this application...?

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  8. #15
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    Many thanks for giving me some more input on my situation gents. I need to find out if these sensors are indeed fitted to my vehicle and check them out. I have looked at elsawin for a removal procedure and it seems to show that they are fitted on the v8 tdi, in the engine bay, one in each turbocharger body. I need to have a look myself. I will also replace the bad glowplug.

    Regarding the handbook procedure for dpf cleaning during driving. I have indeed tried this a few times. Best I could do was get it to go off for 5 mins before returning. I suspect that this feat is probably a red herring!

    Do my dpf pressures and soot/ash readings seem normal to you guys? or getting blocked?

  9. #16
    Benevolent Dictator Uwe's Avatar
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    What kind of differential pressures are you seeing at idle?

    The fact that both pressure sensors have an offset value of 0 seems a bit questionable, but isn't totally implausible either.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  10. #17
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    The differential pressures across both dpf's are reading zero at idle.

    When I read the sensor data with the engine sitting at 2300rpm (no load) I was getting differential readings of 29mbar across each dpf.

    Thanks again.

    Ben.

  11. #18
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by benr8440667 View Post
    The differential pressures across both dpf's are reading zero at idle.
    I find that strange. There should be some pressure differential across them at idle. Maybe just a few mbar, but not zero.

    How long have you owned this vehicle? Is there any chance that the ECUs have been tinkered with and the DPFs have been gutted?

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  12. #19
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    I have owned the car for three years. Its been passing statutory mot tests on emissions every year no problem.
    ive been under the car a few times since ive had it and never noticed any new welding seams on the dpfs.

    I havent noticed it smoking badly either. But nonetheless this is a very interesting avenue to explore. I Wouldnt be surprised if they have been messed with- Would explain some things. I am Planning on cleaning them out soon but this will be somewhat of a non-event if they are hollow!

    I will get underneath asap and do some investigation. Annoyingly i have got a lift but its lying on the floor in a shed due to me moving house recently and loosing my big garage (i really miss that garage. Sob Sob!)

    Also I have read that those dpf pressure sensors are a weakness specifically on the 4.2tdi for some reason. And i believe that the gearbox has to be lowered to gain access. Dont think I can do that without a lift.

    Thanks for helping me out.

    Ben.

  13. #20
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    ...Sorry to go on gents but Another thing that i have found very strange is the fact that i have a permanent dpf warning on the dash display but no dpf fault codes stored in the engine control modules.
    This could possibly be explained by someone having fiddled with the ECU coding... I wonder???

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