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  1. #1
    Silky-S3's Avatar
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    Question S3 Issue - Sticky Falling Revs with Shudder - Help Needed

    Hi guys,

    I’m hoping you can help...

    My S3 has suddenly developed a strange shudder/noise when the revs are falling and falling through about 1,500 rpm. It only happens in neural, when the revs are falling after rev’ing the car (zero throttle). It gets to about 1,500 rpm, the revs suddenly fall slower (like going through a sticky spot) and there is a slight shudder/noise and then it goes away again. Happens every time. Can’t feel it when driving and it pulls very clean all the way from 0 rpm to the redline.

    Anyone got any idea what it could be? I’m thinking vacuum issue, or some sort of air leak? No faults on VCDS by the way.

    Thanks!
    S3 8V Sportback Stronic, Estoril Blue Crystal Effect, Black Interior, Adaptive Cruise with Stop & Go & Pre Sense, Super Sports Seats with Electric Lumber, LED Headlights, Interior Lighting Pack, Hill Hold Assist, Privacy Glass, Comfort Package, Technology Package with Audi Connect, Advance Key, Folding Door Mirrors, Extended Mono.Pur Interior, Front and Rear Parking Sensors, Audi Sound System.

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  3. #2
    warren_S3's Avatar
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    Hmmmmmmmmmm

    Initially I was thinking air leak, but .... further questions:

    1) What mileage are you at?
    2) Who fitted your fuel pump (and when) / was cam follower checked at same time?
    3) Have you checked to see if the ITG hose that that attaches to the turbo (that goes down back of engine) is clamped properly - preferrably with the OEM hose clamp that is self adjusting?
    4) Have you ever changed the plugs?

    For some reason MAF came into my head but dont think it will be. Peolpe mention smoke testing for air leaks on here, but to date I've never found anyone who professes to be able to do it.
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  4. #3
    Silky-S3's Avatar
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    Quote Originally Posted by warren_cox View Post
    Hmmmmmmmmmm

    Initially I was thinking air leak, but .... further questions:

    1) What mileage are you at?
    2) Who fitted your fuel pump (and when) / was cam follower checked at same time?
    3) Have you checked to see if the ITG hose that that attaches to the turbo (that goes down back of engine) is clamped properly - preferrably with the OEM hose clamp that is self adjusting?
    4) Have you ever changed the plugs?

    For some reason MAF came into my head but dont think it will be. Peolpe mention smoke testing for air leaks on here, but to date I've never found anyone who professes to be able to do it.
    Thanks for your quick reply Warren:

    1) What mileage are you at? About 9,000
    2) Who fitted your fuel pump (and when) / was cam follower checked at same time? FP internals fitted by myself along with new follower (old one had no wear), fitted about 3,000 miles ago
    3) Have you checked to see if the ITG hose that that attaches to the turbo (that goes down back of engine) is clamped properly - preferrably with the OEM hose clamp that is self adjusting? Not yet, will check this. Gonna try to refit it with the OEM clamp this weekend.
    4) Have you ever changed the plugs? Yes same time as FP internals, 3,000 miles ago.

    Thanks
    S3 8V Sportback Stronic, Estoril Blue Crystal Effect, Black Interior, Adaptive Cruise with Stop & Go & Pre Sense, Super Sports Seats with Electric Lumber, LED Headlights, Interior Lighting Pack, Hill Hold Assist, Privacy Glass, Comfort Package, Technology Package with Audi Connect, Advance Key, Folding Door Mirrors, Extended Mono.Pur Interior, Front and Rear Parking Sensors, Audi Sound System.

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  5. #4
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    Did you fit HPFP in a clean environment (as much as possible in real world), and then use the recommended lube to bed it in?

    Might be worth whpping out a plug to just check it. If they look dirty clean them up, and refit.
    Audi S3 Panther Black [2011] Build Thread
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    Planned Mods: Revo Stg1+ with DSG map, Revo CAI, custom exhaust, H&R Trax spacers, EM Tuning LED interior lights, R8 oil cap, Porsche coolant & brake fluid cap

  6. #5
    Silky-S3's Avatar
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    Quote Originally Posted by warren_cox View Post
    Did you fit HPFP in a clean environment (as much as possible in real world), and then use the recommended lube to bed it in?

    Might be worth whpping out a plug to just check it. If they look dirty clean them up, and refit.
    Yep, it was spotless (I’ve got a engineering workshop which has clean room), and used plenty of lube to bed in. Are you thinking it could be the FP? I'll check the plugs, FP/CF, and intake hose this weekend and report back...
    S3 8V Sportback Stronic, Estoril Blue Crystal Effect, Black Interior, Adaptive Cruise with Stop & Go & Pre Sense, Super Sports Seats with Electric Lumber, LED Headlights, Interior Lighting Pack, Hill Hold Assist, Privacy Glass, Comfort Package, Technology Package with Audi Connect, Advance Key, Folding Door Mirrors, Extended Mono.Pur Interior, Front and Rear Parking Sensors, Audi Sound System.

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  7. #6
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    I'm currently having what sounds like an identical issue - car's done 75k and is on standard fuel pump internals. Cam follower changed at 60k. From a few other posts I've read it sounded like it could be a failing PCV - I'm fitting a catch can at the weekend and am hoping that resolves it. May be a red herring but just throwing it out there.....

  8. #7
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    Quote Originally Posted by essIII View Post
    I'm currently having what sounds like an identical issue - car's done 75k and is on standard fuel pump internals. Cam follower changed at 60k. From a few other posts I've read it sounded like it could be a failing PCV - I'm fitting a catch can at the weekend and am hoping that resolves it. May be a red herring but just throwing it out there.....
    Thats what I'm thinking too mate, air or vacum leak. I dont see how it could be the FP. Let me know how you get on with the catch can.

    Thanks
    S3 8V Sportback Stronic, Estoril Blue Crystal Effect, Black Interior, Adaptive Cruise with Stop & Go & Pre Sense, Super Sports Seats with Electric Lumber, LED Headlights, Interior Lighting Pack, Hill Hold Assist, Privacy Glass, Comfort Package, Technology Package with Audi Connect, Advance Key, Folding Door Mirrors, Extended Mono.Pur Interior, Front and Rear Parking Sensors, Audi Sound System.

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  9. #8
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    Be very careful when doing up the bolts which hold on the plate which attaches to the head (for the catch can). I remember reading someone overtightened them and stripped the insides out of the aperture. Cost a lot to put right. Not much beyond hand tight. Be interested to see if this cures it as it's not the greatest part but I'd expect it to outlast 10k!
    Audi S3 Panther Black [2011] Build Thread
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  10. #9
    Silky-S3's Avatar
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    Well, I've just:

    Checked cam follower and fuel pump, all fine
    Checked and tightened all hose clamps on CAI, all fine, 1 or 2 a little lose
    Cleaned MAF, all fine, however the bottom bolt was loose,

    and Its cured! Very strange....

    S3 8V Sportback Stronic, Estoril Blue Crystal Effect, Black Interior, Adaptive Cruise with Stop & Go & Pre Sense, Super Sports Seats with Electric Lumber, LED Headlights, Interior Lighting Pack, Hill Hold Assist, Privacy Glass, Comfort Package, Technology Package with Audi Connect, Advance Key, Folding Door Mirrors, Extended Mono.Pur Interior, Front and Rear Parking Sensors, Audi Sound System.

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  11. #10
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    O, and I topped it up with oil to the Max mark...

    Was gonna check plugs as well, but it was fixed before I got to them.
    S3 8V Sportback Stronic, Estoril Blue Crystal Effect, Black Interior, Adaptive Cruise with Stop & Go & Pre Sense, Super Sports Seats with Electric Lumber, LED Headlights, Interior Lighting Pack, Hill Hold Assist, Privacy Glass, Comfort Package, Technology Package with Audi Connect, Advance Key, Folding Door Mirrors, Extended Mono.Pur Interior, Front and Rear Parking Sensors, Audi Sound System.

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  12. #11
    L1ARR's Avatar
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    Glad you sorted out the problem Silky.

  13. #12
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    Quote Originally Posted by L1ARR View Post
    Glad you sorted out the problem Silky.
    +1
    Audi S3 Panther Black [2011] Build Thread
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  14. #13
    Silky-S3's Avatar
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    Cheers guys. Can move on to next mod now!
    S3 8V Sportback Stronic, Estoril Blue Crystal Effect, Black Interior, Adaptive Cruise with Stop & Go & Pre Sense, Super Sports Seats with Electric Lumber, LED Headlights, Interior Lighting Pack, Hill Hold Assist, Privacy Glass, Comfort Package, Technology Package with Audi Connect, Advance Key, Folding Door Mirrors, Extended Mono.Pur Interior, Front and Rear Parking Sensors, Audi Sound System.

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  15. #14
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    Ended up tiling a bathroom floor instead of fitting the catch can this weekend. Will update the thread when I eventually get round to fitting it to let you know if it resolved my erratic idle.

  16. #15
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    Quote Originally Posted by warren_S3 View Post
    Be very careful when doing up the bolts which hold on the plate which attaches to the head (for the catch can). I remember reading someone overtightened them and stripped the insides out of the aperture. Cost a lot to put right. Not much beyond hand tight. Be interested to see if this cures it as it's not the greatest part but I'd expect it to outlast 10k!
    Cheers for the tip on bolt tightness - short story is that the installation of the catch can seems to have resolved my idle issues - revs fall back to about 800 rpm rather than clinging on to 1500.

  17. #16
    warren_S3's Avatar
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    Quote Originally Posted by essIII View Post
    Cheers for the tip on bolt tightness - short story is that the installation of the catch can seems to have resolved my idle issues - revs fall back to about 800 rpm rather than clinging on to 1500.
    Nice one mate, pleased for you. Know how you must have felt as mine was doing my head in on the 8P2!
    Audi S3 Panther Black [2011] Build Thread
    Mods: Revo Stg2, Blueflame TBE, Eibach Pro springs, R8 oil cap

    On order: Audi S5 3.0V6T Coupe Black Edition, Phantom Black [Due 26 May 2014]

    Planned Mods: Revo Stg1+ with DSG map, Revo CAI, custom exhaust, H&R Trax spacers, EM Tuning LED interior lights, R8 oil cap, Porsche coolant & brake fluid cap

  18. #17
    Silky-S3's Avatar
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    Glad you got sorted mate. Might fit a catch can at some point.
    S3 8V Sportback Stronic, Estoril Blue Crystal Effect, Black Interior, Adaptive Cruise with Stop & Go & Pre Sense, Super Sports Seats with Electric Lumber, LED Headlights, Interior Lighting Pack, Hill Hold Assist, Privacy Glass, Comfort Package, Technology Package with Audi Connect, Advance Key, Folding Door Mirrors, Extended Mono.Pur Interior, Front and Rear Parking Sensors, Audi Sound System.

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