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Allroad 2.5 TDI Misfire/Judder Under Load

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by tekno_al, Nov 28, 2011.

  1. tekno_al

    tekno_al New Member

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    Hi all.

    I have a 2000 Allroad 2.5 TDI TIP with 117,000 miles and I am getting problems with "juddering/misfire" after/during a high rpm run (>3000 rpm), accompanied by "grey/black" smoke. The best description I have had is that it feels like "driving over a cattle grid".

    The juddering can occur once off throttle and then trying to accelerate again from a lower rpm. But going above 3000rpm in one of the higher gears, seems to be the trigger point.

    There are no error codes and no drop in power until the misfire kicks in. I have a boost gauge installed in place of the voltmeter and this is not showing a drop in boost during the misfire (stable at around 15psi - is this even correct?), so I'm assuming overfueling??

    Interestingly, if the car is placed into neutral and the rpm is allow to drop to tickover, then there is no judder when applying more throttle.

    Items recently changed (some under warranty, to try and cure it): fuel filter, turbo, injector pump, gearbox, gearbox ecu, control injector, N75 valve.

    I definately have a shot thermostat, as I'm only seeing a constant 80C.... this can't be contributing.... can it?

    also, I do have a DTEK tuning box installed, but the problem is there with/without it.

    Other than that, it's a great car..

    Any thoughts most welcome.

    Alan
     
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  3. adamss24

    adamss24 Well-Known Member

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    Any faults if you scan it with vag-com/VCDS ? I would think it's either a fauty injector or the engine load/speed sensor is goosed. You need a scan first...
     
  4. tekno_al

    tekno_al New Member

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    Hi & thanks for the reply.... I was drifting towards a faulty injector..

    ...after all that typing, I knew I'd miss something from my post..... no fault codes found.. (I have VCDS 10.63)
     
  5. fjtwelve

    fjtwelve Moderator
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    My turbo was running 255kpa less 101 atmospheric presssure = 154kpa boost = 1.54 bar = 22psi at the last dyno run. I am not sure what its running now but i have same intermittent probs as you and same smoke. Problem is eased by cleaning turbo so suspect i have sticking vanes in turbo, especaially as actuator arm will not move 15-20mm on start up as it should. Alternatively the actuator could be shot, but you say your turbo has been replaced.
    The only other thing i can suggest is there is a fuel sytem problem and air is getting in intermittently. The non return valve on top of the filter is a prime suspect, the little rubber seal is prone to getting damaged on assembly and then leaks air. Have you got fuel on top of the filter, if so its could be leaking. I have read that this can fool the fuel pump and it then tries to inject more resulting in over fuelling.
    Will be interested if you solve this, i am concerned i will need to replace turbo (again, don't ask).
     
  6. tekno_al

    tekno_al New Member

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    I've now done the Mr Muscle turbo cleanout, and completely replumbed the vacuum pipes to remove (and also blanked off) the egr from the loop. The upside is, the car is now going like a stabbed rat, but the judder is still there.....
     
  7. murran

    murran Active Member

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    what engine code is this? is it the engine with the hollow cams?
    id pull the rocker covers off and check the cams. symtoms sound the same as an 02 plate allroad i worked on about 2 years ago. cant remember the engine code but it had the hollow light cams with the roller rockers. one of the cam lobes had cracked across and was able to move around on the shaft causing an intermittent lumpyness/misfire.
     
  8. tekno_al

    tekno_al New Member

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    Hi, it's the AKE engine.....and i must admit, i've been trying to put the possibility of it being the cams to the back of my mind....the car is going in for cam belts etc in january, so I'll get the cams checked out then.
     
  9. adamss24

    adamss24 Well-Known Member

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    The AKE never had hollow cams, they were only fitted to the later BDG/BAU/BDH engines the cam roller type... However, if improper oil was used or the car was on Longlife then the AKE cams wear out prematurely. On my allroad (which dropped a valve because a lifter/rocker arm fell and got jammed against a valve thus snapped) the cams vere badly worn and the oil pump chain drive was so slack that you could spin the sproket without turning the oil pump ! Used a set of Kolbenshmidt cams (part of SK group of companies which own Pierburg amongst others and are OEM manufacturers of cams,pistons and engine heads) which are forged and came with INA forged lifters and rocker arms and forged valve spacers. Done the thermostat yesterday as it was stuck open.
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  10. Alski2009

    Alski2009 Member

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    Chris. Yikes, that looks nasty. I was lucky when my engine was spitting out it's rocker arms, the valves failed-shut.

    I'm sure my flywheel and clutch are worn because it has started to judder more than usual............. How long did it take to get that 2.5 v6 TDi lump out?

    With everything out, did you smash the CATs to pieces? Definitely something i want to do soon.
     
  11. davidfox280585

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    my 2.5 bdg cab destroyed the cams and now resides a ake in its place
     
  12. Yappy

    Yappy A4 b6 TDI V6 Quattro Sport

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    If your after decat pipes I have some up for grabs
    Pm me if so
     
  13. adamss24

    adamss24 Well-Known Member

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    It took me a day to get it out and put the new block in then another day to put the cams/lifters/rockers in + time the engine then another day to get the thermostat replaced. All in all it took me about 4 days to rebuild as i had other comitments at the same time + i had to remove the bumper once more to get at the thermostat (could not find a seal at the time and local dealer did not have any in stock). Your clutch Alex is the self adjusting type so it will need the special flywheel and clutch - about 5-600 quid in parts + 1 litre of gearbox oil as some of the oil will drain from the radiator (doubles up as gearbox oil cooler).
    My flywheel had a little play in an out but nothing excessive and it's smooth in operation even after so many miles of towing. If i will keep the car for longer (which most likely i will !) then i would replace the clutch when the warm weather is back ! I still have to do a few suspension arms and geometry check as i am still driving the car as it is 1 year after i've replaced the front track rod ends !
     
  14. adamss24

    adamss24 Well-Known Member

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    I still need to meet you mate, need a downpipe fabricating on my old b5 quattro which has no engine at the moment- awaits for a fully blown 1.9Tdi engine to go in it's place ! Need to pull my finger out really but had too much work lately and with a few ongoing projects this got neglected !
    Need to get the engine in first then i will mess with the wiring loom swapp and the twin intercooler set-up needs modifying to fit the new BV43 turbocharger then the front springs need replacing with a pair of Eibach 1.9 tdi springs. I was hopping that i will have spare time between new year and Xmas but it's seems that there's no rest for the wicked ! Happy new year guys !
    Chris.
     
  15. Yappy

    Yappy A4 b6 TDI V6 Quattro Sport

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    Yeah we do Mate haha well when your all good and ready just give me a call or a pm on here and we can get moving on her
    what sort of power you thinking of running I recon we could push 260 Bhp with the right bits and then throw in a sniff of laughing gas for
    good measures haha

    Anyway happy new year all let this one be full of modifying and good times
     
  16. scorn

    scorn New Member

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    Did you get this sorted in the end? I have the exact same symptoms on my A4 right now. It's been getting progressively worse over the last few months, and there are no fault codes.
     
  17. adamss24

    adamss24 Well-Known Member

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    Pull the rocker covers off and check the cams, lifters and rockers for wear... Automotorsport on ebay do a full rebuild kit including every thing you need for about £1100, you save a good 2-300 from buying them separate !
    This is another one i am doing at the moment, was a non starter apparently and the "specialist" garage took the heads off to check. They found nothing wrong but i found 2 cracked valves (1 broke in my hands after i took it off the guide !)...2 new heads, cambelt kit, thermostat and aux. belts and i am ready to start the engine just i don't have the key yet- garage miss-placed it !

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  18. murran

    murran Active Member

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    your busy there mate. :)

    i like working on these engines. find them very satisfying.
     
  19. adamss24

    adamss24 Well-Known Member

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    I know exactly what you mean ! Got another allroad tonight, owner bought it as spares or repairs with broken cams (later BAU engine code with hollow cams) and he repaired it before X-mas then last month it stopped again- broke 3 cam followers on driver side head. He replaced them with spare ones from when he rebuilt it and noticed the engine is sounding rough. Looking at the cams -trough the filler hole -he's been supplied the wrong cams for the AKE heads and he did not question their suitability with the supplier !
     
  20. tekno_al

    tekno_al New Member

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    Going back to my original post...

    Cam belts etc all replace, timing is spot on.. Rocker covers taken off, cams ok, all valve bits still in place!

    So, I still have the problem and still no fault codes....

    Damned annoying, so would appreciate any further ideas...

    Cheers..
     
  21. murran

    murran Active Member

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    injector leak off test?
     

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