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Facelift S3 hunting under light acceleration

mikemod May 25, 2020

  1. mikemod

    mikemod Registered User

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    I am having issues for a while now with my 2016 FL S3.

    Under light acceleration, especiallay on a hill, the car is hunting, nealy like I am lifting on and off the throttle.
    Even under full throttle I would get a couple of jumps on the way up through the rev range.
    If I just accelerate at about 2500 rpm then that is when it seems to be worse.
    I had the plugs changed which seemed to help but it is back again.

    I have scanned with VCDS and no there are no faults on any of the modules.

    The car is booked in the week after next and I still have warranty but I was just trying to get some ideas because they said if they can't replicate the fault then they will not investate further and due to the COVID-19 restrictions I cannot go out with the mechanic.
     
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  3. mikemod

    mikemod Registered User

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    So leaving the car in this morning, looks like its going be a difficult one to trace so not holding out much hope although they can have the car for as long as they like as I am working from home

    If they do find the issue I will update this and hopefully help anyone else who has similar problems.
     
    N.J.H likes this.
  4. Damo S

    Damo S Registered User

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    So it is intermittent? A likely cause is its misfiring but not enough to register a fault code. A scan wouldn't necessarily pick anything up, but the misfire counts would be recorded in the logs. It records the count for the last drive and an average count over the last 10 drives for each cylinder. The cause of the misfires could be any number of things to be honest. Ask Audi to check (although I'm sure they will anyway) and see if it has been misfiring. It might just be a coil pack on the way out, for example.

    The ECU is incredibly good at fudging things and keeping the engine running, even if there is a fairly significant problem, without telling you something is wrong. The misfire counts are the first place to look if it doesnt feel right. Shame you haven't still got the car because with a phone app such as torque pro and obd port dongle you can check this yourself in minutes. It costs about 15 quid to buy both, and is a worthy investment for check this regularly to make sure you're car is running OK). If its misfiring a lot and on a regular basis causing unburnt fuel to be thrown down the exhaust this will kill the catalytic converter over time.

    Hopefully its just a dodgy coil pack and an easy fix, and not something more labour intensive like a faulty injector. Fortunately the warranty should cover all the work anyway (assuming you don't have a remap or some other mods they can blame).
    Coil packs are a fairly common fault, and they can start to fail making it run a bit lumpy without necessarily giving a fault code (just misfires). If it was me, and one needs be replacing Id be tempted to ask them to replace the other 3 as well for piece of mind (you'd have to pay for the other 3 though).

    Hope you get it sorted soon.
     
  5. mikemod

    mikemod Registered User

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    I have VCDS and checked all the misfire counters yesterday, all showing zero (All standard, no mods)

    I had a coil pack go on my MK6 GTI but it was really bad under load.

    I haven't heard anything back today so will wait and see if tomorrow brings anything.
     
    Kayobong likes this.
  6. Damo S

    Damo S Registered User

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    When they let go completely its awful, but when they start failing they result in the running being a bit lumpy. I would have thought that would register as a misfire though. Maybe something like the cam position sensor?
    just guessing really, but interesting that you have 0 misfires which rules a lot of things out.
     
  7. mikemod

    mikemod Registered User

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    Called today and was told that a misfire has been detected on cylinders two and three, but I didn't see that in my logs.

    The last time it was in they found a fault recorded against both headlight units. I had noticed that the auto level wasn't being performed at start-up.
    They did a software upgrade and that is now fixed.

    Again VCDS had not detected any faults, as I had scanned the car before going in, just wondering if it is not seeing everything now, I have owned the cable for 15 years and it is a genuine one.
     
  8. Damo S

    Damo S Registered User

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    I did think it seemed a bit strange that you had none at all. I usually have a 1 or 2 on at least one of the cylinders after every drive.
     
  9. mikemod

    mikemod Registered User

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    So a quick update on my issue, so far the following has been changed.

    Plugs
    Coil Packs
    Low pressure fuel pump
    High Pressure fuel pump
    PCV

    The issue remains :disappointed:
     
  10. Sparks43

    Sparks43 3rd Gear

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    I would assume you're looking at an ECU now then or Injectors - Do you use good quality High Octane Fuel although this sounds more than that
     
  11. Damo S

    Damo S Registered User

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    Injectors, ECU, wiring loom, valves, pistons, cam shafts. still could be one of numerous things. When I had some misfires on one cylinder it turned out to be a damaged exhaust camshaft.
     
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  13. Kayobong

    Kayobong Registered User

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    Have you owned the car from new? I had pretty much this exact issue on my MK6 GTI.
     
  14. mikemod

    mikemod Registered User

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    Yes, first owner, car completely standard, 35K miles, never had any issues until now.

    @Kayobong What was the problem in the end on the GTI?
     
    Last edited: Jun 19, 2020
  15. mikemod

    mikemod Registered User

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    Yes, always use BP Ultimate as it is really the only 97 you can get here in NI.

    They are pulling out the injectors to flush them through.
     
  16. mikemod

    mikemod Registered User

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    So into the fourth week but no further on, injectors flushed out and inlet system cleaned with walnuts :grinning:
     
  17. Damo S

    Damo S Registered User

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    Doh! The head will be coming off next I would assume
     
  18. mikemod

    mikemod Registered User

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    Yes, funny you should mention that but they are waiting on Audi coming back to them but that was mentioned.

    When they checked the inlet valves, 2 and 3 had carbon build up, 1 and 4 were clean.

    I did notice that there have been 3 new revisions of injectors since my car was built, but maybe nothing in that.
     
  19. Damo S

    Damo S Registered User

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    They actually replaced the injector on mine after cleaning didnt fix it, then since that didn't fix it either the head came off which is when they discovered the cam shaft issue.
     
  20. mikemod

    mikemod Registered User

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    Audi have asked the dealer to replace all 8 injectors, I will see how that goes later in the week.
     
    Last edited: Jun 29, 2020
  21. Damo S

    Damo S Registered User

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    At least your going to have a pretty tip top car once they have gotten to the bottom of it.
     
  22. mikemod

    mikemod Registered User

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    So all injectors and throttle body replaced and issue still there, still no error codes.

    I'm going to get the car back today to see if driving it more can generate an error code and just waiting for Audi Germany to come back with next possible way forward.
     
  23. Damo S

    Damo S Registered User

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    I'm surprised they are going for that since depending on whats causing the misfire it can wreck the pistons.
     
  24. wab172uk

    wab172uk Now in an X3 M40i

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    Injectors is what was faulty with mine. Caused the piston to disintegrate. You could be looking at a new engine.

    If they refuse and say it's never happened before, let me know. I can give you some info to prove it's happened before
     
    X3man, mikemod and Damo S like this.
  25. mikemod

    mikemod Registered User

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    They have decided to keep the car after more feedback from Audi so just getting a loner for a while.
     
  26. mikemod

    mikemod Registered User

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    So coming up to six weeks, took the car out for a run yesterday from the dealers and just the same, but I forgot how quick it was :tongueclosed:
    They have now replaced everything apart from the main part of the engine.

    So driving an A5 coupe 190 diesel and looks like I will be for a while longer :disrelieved:
     
  27. Damo S

    Damo S Registered User

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    They had a mine for over 2 months. I too had an A5 couple 190 Diesel, for which I did rather like the interior lighting. The S3 seemed dark and a bit boring inside once I got it back.
     
  28. wab172uk

    wab172uk Now in an X3 M40i

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    So it's not fixed?

    Your dealer sound like they are wasting time and effort. I'd be demanding a new engine if I was you.
     
  29. K96

    K96 Registered User

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    I had this exact issue on my S3 8P but the only fault code I was getting was random cylinder misfire.

    Turns out that the fuel valve that screws into the manifold had cracked. I'd get audi to check this part just encase.

    Sent from my SM-G973F using Tapatalk
     
    mikemod likes this.
  30. mikemod

    mikemod Registered User

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    They have replaced the high pressure fuel pump, would that be the same area.
     
  31. mikemod

    mikemod Registered User

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    I have to say the dealer has been great under the circumstances.
    With the Covid-19 issues ongoing they have only 50% workshop and all support staff at Audi HQ are either working from home or only part-time.

    I work with with embedded controllers myself so know how hard it is to find an issue like this so they have my sympathy.

    The A5 I have to drive is really quite nice so no real hardship.
     
  32. mikemod

    mikemod Registered User

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    If the S5 hadn't gone diesel and changed to a torque convertor gearbox I would seriously be considering it.
     
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  34. mikemod

    mikemod Registered User

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    So investigation still ongoing, lots of runs and logs taken and sent to Germany, ECU swapped but still no further on.
    Car run with prop shaft removed to eliminate diff and Haldex

    Dual mass flywheel to be replaced on Monday.
     
    Kayobong likes this.
  35. Kayobong

    Kayobong Registered User

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    You're going to have a brand new car by the end of this.
     
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  36. mikemod

    mikemod Registered User

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    So another week goes buy and no further on, not sure I am going to see this car again.
    I can't believe this has gone on for so long for what seemed like a simple fault.
     
    Kayobong likes this.
  37. Kayobong

    Kayobong Registered User

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    That’s quite mad, it must be very frustrating for you. Hopefully it gets sorted ASAP
     
    mikemod likes this.
  38. mikemod

    mikemod Registered User

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    Yes, it's been a long time and although I have been patient and they have lent me a nice car I think we need to see a conclusion soon.

    If the new S3 had been out already I probably would have bought one but not sure how to go forward if there is no resolution in the next couple of weeks.
     
  39. Peter82

    Peter82 Registered User

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    I really don't fkin uderstand WHY on earth they been messing so much with it and they just didn't send it to germany first place and send you the new one?? That would be much easier and even cheaper for them..
    I suggest you to NOT use VCDS **** anymore it isn't PROPER germany stuff it is basically an USA wannabe replica which audi isn't happy about it but they left it for USA shoppers as there is no proper germany support ... I would use genuine original volkswagen/audi software what exactly they have germany factory where you have to connect to audi server and only then do car diags...
     
  40. mikemod

    mikemod Registered User

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    Well, maybe some good news at last..

    They replaced the Dual Mass Flywheel and after a couple of initial tests it looks like the issue has gone, they want to test it overnight and then I might be getting it back tomorrow :redrs4::racer:
     
    Peter82 likes this.
  41. CanadaA3wales

    CanadaA3wales Canadian living in South Wales - Audi A3 8V 150BHP

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    Make sure you take it for a test drive with the manager with all the issues you've had.
    If they are trying to fob you off saying its fixed or just slightly better I would demand them get you the exact same car or new car.
     
  42. mikemod

    mikemod Registered User

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    Got the car back today, all feels good, took it up a road I could always replicate the issue and no problems.

    So looks like the Dual Mass Flywheel has fixed the problem, we got there in the end.

    The dealer has been superb all along, even with Covid issues restricting support and only half the workshop team allowed in at a time
    I had also had a nice car for the duration.
     
    TYb, X3man and Kayobong like this.
  43. X3man

    X3man Well known member

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    all's well that ends well :icon thumright:
     
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