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I’m at a loose end, please help! S3 8V intermittent rough idle.

Leedavies_S3 May 13, 2018

  1. Leedavies_S3

    Leedavies_S3 New Member

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    Hi everyone, long time user of the forum but I’ve finally decided to create an account as I really am at a lose end now.

    I have a 2014 Audi S3 8V and it has an intermittent rough idle. The revs just seem to drop away but doesn’t always show on the Rev counter. It sort of stutters and grumbles and the exhaust sort of burbles and then it just stops and goes back to normal.

    I took it to a vag specialist I use and they scanned it and diagnosed it as the camshafts over and under advanced, changed them under warranty as I’d only had the car a few months costing a huge amount ( thank god for warranty) had it back and on my way home I booted it and then all of a sudden it stuttered and I was left on the side of the road, took it back thinking they had done something wrong but it was diagnosed as a stuck open injector? New one of them and it was good to go! But that’s a story for another day.

    Anyway, I had the car back and after a few days it started again, the weird rough idle that only happens sometimes. I’ve searched all over the forum and there isn’t a single person who seems to of had the same problem as me. I changed the pcv valve as a precaution but still to no avail!

    Sorry for the long winded post but someone PLEASE throw some ideas my way! Thanks.
    Lee
     
  2. ictus_duplo2

    ictus_duplo2 New Member Audi S3 Navarra Blue Classic Manual

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    My car does not like 95 Ron fuel as it gets a slight stutter that you can feel only at low revs. Its fine on 99.
     
  3. Leedavies_S3

    Leedavies_S3 New Member

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    Can’t be that it’s always been run on 99 not once have I put anything not premium in!
     
  4. Bayzoo

    Bayzoo Glovebox Demon TeamMisano Audi S3

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    Are you running any hardware or software mods?
     
  5. Leedavies_S3

    Leedavies_S3 New Member

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    No mate nothing!
     
  6. Bayzoo

    Bayzoo Glovebox Demon TeamMisano Audi S3

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    Can you capture footage and post it on here? I’m no mechanic but without seeing the issue it’s hard to tell.
     
  7. Leedavies_S3

    Leedavies_S3 New Member

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    That’s a good idea, I’ll try to capture it but sometimes it won’t do it for a few days and others it will do it all the time
     
  8. Bayzoo

    Bayzoo Glovebox Demon TeamMisano Audi S3

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    No worries - might enable some forum members who are mechanically skilled to chip in with a more accurate diagnosis.
     
  9. Matt Titanium

    Matt Titanium Well-Known Member Team Navarra Audi S3 Manual

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    Any delayed/unusual starting whilst cranking or misfire for a few seconds on start-up?
     
  10. davc

    davc Well-Known Member Team Glacier Audi S3 saloon quattro S tronic S3 Saloon

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    My first thought reading this was the pcv valve, but I see you have already changed it.

    I had the same issue on my 8p S3 and a new pcv cured it.

    When were the spark plugs last changed(should be every 5 yrs/38k)?

    Carbon build up in the inlet valves can also cause a rough idle. This technically shouldn't happen on the 8v as the engines run both port and direct injection, but you never know.

    Hope you get to the bottom of it mate as you must be pulling your hair out.
     
  11. Jimbbobw1977

    Jimbbobw1977 Active Member

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    We had the issue on our 8P 2.0tsi with rough idling as above, coked up engine full of carbon deposits. Head off job and a clean up. Been okay since.
     
  12. Leedavies_S3

    Leedavies_S3 New Member

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    Doesn’t seem to be, although I have noticed it cranks a couple times more Than usual on start up now, but nothing I’d worry about if you get me
     
  13. Leedavies_S3

    Leedavies_S3 New Member

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    Heads been off as they’ve changed the camshafts!
     
  14. Leedavies_S3

    Leedavies_S3 New Member

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    Oh
    you know what, it was serviced just before I had it I’ll have to check if spark plugs have been done but I should think so, and yes I am really pulling my hair out!
    I’ve spent more on this car than I have on any of my other cars but I can’t help but still love it
     
  15. Leedavies_S3

    Leedavies_S3 New Member

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    Still haven’t managed to get a video due to work but it hasn’t done it this week... so annoying as it’s intermittent!
     
  16. Matt Titanium

    Matt Titanium Well-Known Member Team Navarra Audi S3 Manual

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    Sounds similar to the issues I had with my 2013 1.8. Intermittent, no fault codes recorded, sometimes cranked a bit longer than normal cold or hot, sometimes missing on start-up, rough idle, sometimes worse when the engine was cold.
    Main dealers and Audi struggled to find any fault.
    They 'updated' the ECU software with a modified version from Audi, no better.
    It turned out to be fuel injectors, they cleaned them in an ultrasonic bath, no better. They ended up replacing all the direct and indirect injectors (under warranty) and it was ok after that.
     
  17. Leedavies_S3

    Leedavies_S3 New Member

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    I hope it isn’t injectors as I had one fail a while ago and it cost a bloody fortune
     

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