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AKE / BUA 2.5 V6 TDI Engine Misfire, Juddering, Diesel Knock

Mark-C Oct 10, 2019

  1. Mark-C

    Mark-C New Member

    Hi gentlemen, please bare with me on this post as i want to give as much info on this as possible. ive seen some similar posts but wanted to create a new thread so i could keep it updated with my progress

    I recently purchased this vehicle (allroad C5 BUA engine) with the knowledge it needed some work doing, air suspension faults, control arm bushes, oil leaks, noisy cams, faulty alternator etc etc. probably a crazy idea in hindsight but i liked the idea of a challenge at the time.
    car has genuine 98000 on the clock and i picked it up for a bargain.

    so far i have completed the suspension work, rebuilt compressor with new piston and barrel, replaced all failed bushes and even replaced the eccentric bolts on the rear control arms, replaced front os strut with new air bag, replaced rear os hub and wishbones which had damage from a crash at some point in its life. car now handles as it should and sits very well on the road, air suspension better than new which i was all very happy about.

    whilst doing the suspension work i replaced the faulty alternator with second hand, seems like the leaky cam seals had covered it in oil and destroyed it, new alternator working all ok, great!

    my next step was to replace the cams with upgrade to hardened cams and replace water pump and aux belt, i also had in mind to replace the oil housing seals and oil breathers as ive read stories about crank case pressure on these particular engines which should have brought the car back up to standard.

    unfortunately my happiness was cut short today whilst driving up the motor way, i had to drive the car when i probably shouldn't have. i had coasted along the whole way as i wasnt confident in putting any stress on the engine knowing i had worn cams and leaky cam seals. whilst coasting along at about 65mph suddenly the car developed an extremely bad vibration going through the whole car.
    i immediately pulled in to the services to investigate. listening the the engine i can hear the distinct sound of a misfire and under load im getting very bad diesel knock.
    VCDS shows cyl 1 and 3 injectors running at -2.50mg/s and cyl 4, 5, 6 at +2.5mg/s at idle so the engine is definitely compensating for something. im unsure of cyl 2 which im guessing is the needle position injector? i checked the pump timing and it seems all over the place and could not get a good reading on the graph at all.

    my first thoughts are that some rockers have jumped out so tomorrow i will be removing the rocker cover and inspecting the cams more closely.

    VCDS has thrown up a list of faults, after some reading, some of the faults seem to correspond to the 2 pin plug / cable that goes to the alternator so im wondering if anyone has any further thoughts. here is the scan i saved from earlier. luckily i had my laptop and cable handy at the time.

    VIN: WAUZZZ4B15N023517 License Plate:

    Chassis Type: 4B (4B - Audi A6/S6/RS6/allroad C5 (1998 > 2006))

    Scan: 01 02 03 06 08 15 16 17 18 22 34 35 36 37 45 55 56 57 65 67

    75 76 77

    VIN: WAUZZZ4B15N023517


    Address 01: Engine Labels: 059-907-401-AKE.clb

    Part No: 8E0 907 401 J

    Component: 2.5l/4VTEDC G000AG 0006

    Coding: 06006

    Shop #: WSC 02334

    VCID: 2C509C9FDC18905ED1-4A9C

    Subsystem 1 - Part No: 00008059

    Component: 130 106LC 106LCV79686256491256

    WAUZZZ4B15N023517 AUZ7Z0D2675426

    2 Faults Found:

    01117 - Generator Terminal DF Load Signal

    27-10 - Implausible Signal - Intermittent

    16487 - Mass air flow sensor (G70)

    P0103 - 35-10 - Signal too High - Intermittent

    Readiness: 1 1 X X X


    Address 02: Auto Trans Labels: 01V-927-156.lbl

    Part No: 4Z7 927 156 N

    Component: AG5 01V 2.5lTDI RdW 2222

    Coding: 00001

    Shop #: WSC 00000

    VCID: 51AEED6B9BFA9DB682-5072

    1 Fault Found:

    18265 - Load Signal

    P1857 - 35-00 - Error Message from ECU


    Address 03: ABS Brakes Labels: 8D0-907-389.lbl

    Part No: 4Z7 907 389 A

    Component: ABS/ESP allrad D66

    Coding: 06457

    Shop #: WSC 02335

    VCID: 4A9CFA0776ACAE6EC3-5000

    1 Fault Found:

    18265 - Load Signal

    P1857 - 35-10 - Error Message from ECU - Intermittent


    Address 15: Airbags Labels: 4B0-959-655-AI84.lbl

    Part No: 4Z7 959 655 M

    Component: Airbag 8.4EP 1000

    Coding: 0001106

    Shop #: WSC 02335 785 00200

    VCID: 59BE154B930AD5F67A-5072

    No fault code found.


    Address 17: Instruments Labels: 4B0-920-xxx-17.lbl

    Part No: 4B0 920 981 J

    Component: KOMBI+WEGFAHRS. VDO D17

    Coding: 04460

    Shop #: WSC 00001

    VCID: 2D56919BE7029956C6-5072

    WAUZZZ4B15N023517 AUZ7Z0D2675426

    No fault code found.


    Address 34: Level Control Labels: 4Z7-907-553.lbl

    Part No: 4Z7 907 553 F

    Component: - 2C1A1 X060

    Coding: 25500

    Shop #: WSC 12790

    VCID: 4898C00F68A05C7ED5-5000

    1 Fault Found:

    01316 - ABS Control Module

    79-10 - Please Check Fault Codes - Intermittent

    End-------------------------(Elapsed Time: 06:47)--------------------------

    thanks in advance for any info you can help me with. im determined to get this car running now as im invested in it and will keep this thread updated as much as possible.

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