Exhaust rattle/vibration around 1000RPM whilst revs dropping

[Actionman_RM]

This is bugging me!

Driving a 2010 S-tronic S4. when i slow down to come to a junction, and the revs drop, i get a horrible rattle noise from the exhaust. when i look underneath and try to replicate the fault by blipping the throttle, the exhaust visibly vibrates for a few seconds whilst around the 1000-1100 RPM mark, and makes a horrible tinny rattle. the car doesn't have to be warm to get the fault. i have had it on a ramp and the exhaust mounts are ok and there is nothing loose touching the exhaust. It seems to be some sort of resonance.

Has anybody experienced this?

Nick

[VeNoMS4]

There is a thread talking about this. I assume you have an after market exhaust. In that case, the current explanation is that since the aftermarket exhaust is lighter than OEM, the exhaust no longer dampens the inherent vibration produced by the exhaust gases. Which part of the exhaust do you see vibrating?

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[Actionman_RM]

No i don't have an after market exhaust. car is completely stock at the moment. vibrates from the down pipe join back.

[VeNoMS4]

No i don't have an after market exhaust. car is completely stock at the moment. vibrates from the down pipe join back.

hmm.. that is interesting. i've only seen the vibration you are talking about, happen with AM systems. Maybe instead of the actual pipes being loose, maybe it's something around it that's loose? I thought the stock system was just so damn heavy that it dampens any vibration. Maybe there is some sort of blockage that affects the low velocity gas flow at low RPM's that causes the gases to get turbulent in the pipes? just thoughts..

[SportVier]

Sounds like you might have had something fail internally that is rattling? That is, some vibration was always there, but now you have a "horrible tinny rattle" caused by a an internal crack or broken weld?

[dizzlesizzle]

It's probably the honeycomb thing in one of the cats. Came loose and at low idle it's vibrating inside.


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[Actionman_RM]

thanks for your replies. I think it must be something internal that has failed, possibly a blockage of some sort. i can't find anything loose holding the exhaust or any of the exhaust itself. Maybe i'll just have to upgrade. can't imagine a stock replacement would be that much cheaper.

[MrFunk]

If you have a vid it would help.

But:
The downpipes on this car vibrate the exhaust around 1k rpm. It's more noticeable with aftermarket exhausts which are lighter that oem and get vibrated more... and even more-so in cold weather.
I don't know if it goes away after a while or if you just get used to it but I don't notice it anymore in my car at all.

(if you watch vids on yourtube of ppl revving their S4's to show off an exhaust or similar, you will almost always hear this rattle if you listen for it).

[Actionman_RM]

i will try and post a video of it. it is not a 'normal' sound. it kinda sounds like this:

https://www.youtube.com/watch?v=xezBCEiyssY

you can get it to constantly do it if you can hold it at the right RPM, but most noticeable when ease off the throttle and let the RPM drop. Maybe a little less 'tinny' than the video shows.

[MrFunk]

i will try and post a video of it. it is not a 'normal' sound. it kinda sounds like this:

https://www.youtube.com/watch?v=xezBCEiyssY

you can get it to constantly do it if you can hold it at the right RPM, but most noticeable when ease off the throttle and let the RPM drop. Maybe a little less 'tinny' than the video shows.

Yep. It's the same noise. Mine did this - went away or I got used to it. My friend's S4 did the same. You can hear the same noise in lots of exhaust vids with ppl revving. I only noticed mine do that in the winter.
My friend was so annoyed with it he put his OEM exhaust back on and it still made the noise - but not as bad. He didn't notice it until I pointed it out to him though.

FWIW though - my other friend with an 2010 never had this vibration issue. Go figure...

[skiptowncat]

Centre resonator. Same thing has happened on a few cars including mine.

[Actionman_RM]

So a change in exhaust may or may not solve the issue. I think it's more annoying as its around the rpm just before the downshift at low speed.

Thanks for your advice!

[Actionman_RM]

so here is a video of the noise.....

https://youtu.be/ujeTIi5gs8k

[skiptowncat]

so here is a video of the noise.....

https://youtu.be/ujeTIi5gs8k

95% sure it's the centre resonator, mine did exactly the same until I got aftermarket exhaust.

[MagillaGorilla]

so here is a video of the noise.....

https://youtu.be/ujeTIi5gs8k

My car does 100% the exact same thing. Looks like I'll have no choice but to get an AWE/Borla exhaust as my first troubleshooting step.

[s4matty]

My car does 100% the exact same thing. Looks like I'll have no choice but to get an AWE/Borla exhaust as my first troubleshooting step.

Im going through the same thing on my brand new borla..
Going to change the flex pipes tmrw to shorter ones..
Borla are the worst for viabratons because the flex pipes are too long and go all the way down half way through the 1st bends in the dp's causing alot of side hanging weight and stress on the flex pipes..

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[MagillaGorilla]

Im going through the same thing on my brand new borla..
Going to change the flex pipes tmrw to shorter ones..
Borla are the worst for viabratons because the flex pipes are too long and go all the way down half way through the 1st bends in the dp's causing alot of side hanging weight and stress on the flex pipes..

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I just put on a Touring system. Stock downpipes. I'll try to remember to see if it still does it later. Probably does. Doesn't bother me much though.

[bberg22]

My '13 does this too. Let me know if you have any success in fixing it.

[PenttisHSR]

2010 6MT - STD Exhaust system - Mine's exactly the same.

[Actionman_RM]

2010 6MT - STD Exhaust system - Mine's exactly the same.

Would you say it a fault that needs fixing? Just doesn't seem right


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[PenttisHSR]

Would you say it a fault that needs fixing? Just doesn't seem right

I'm much happier now that I know bberg22 and you've got the same noise

[chrisucf99]

I'd take it into a muffler shop. They'll get it on a lift and see what's up.

[jbmark33]

99% sure that's your downpipes, I had both of mine replaced in the last few months and it fixed this issue.

[maty360414]

My muffler shop told me that it was flex pipe, I have a 13 S4. same noise here

[s4matty]

My muffler shop told me that it was flex pipe, I have a 13 S4. same noise here

Yes there correct
It's the outside wire/mesh that rubs on the inner flex that causes the viabratons and noise.
I changed a guys awe flex pipes to another style/brand and it was fixed

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[Zman84]

Mine is starting to do this as well. Wouldn't it be covered under the emissions warranty?

[Tashfeen]

I have a 2014 DSG (UK) and I am getting the same noise. Booked in with my local dealer and I was told it is 'normal' and is the mesh (see pic) which vibrates at lower RPMs.


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[MrFunk]

I have a 2014 DSG (UK) and I am getting the same noise. Booked in with my local dealer and I was told it is 'normal' and is the mesh (see pic) which vibrates at lower RPMs.


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Exactly this.

[xxdunnxx]

http://www.audizine.com/forum/showth...bration-Thread

It happens at higher RPM's in most aftermarket systems and much much worse. It's likely the flex sections and the design of the headers and downpipes leading up to there.

[-leman-]

It's flex sections failing as said above.

I was getting the same vibration / noise on my OE exhaust at 1000 RPM exactly since purchasing my car (got it pre-owned). Gutted the cats (retaining otherwise OE exhaust) down the road but noise / vibrations remained. In about 6m thereafter changed the flex sections (there was an audible leak from them) by cutting the OE ones out and welding the new ones in their place (same size as OE ones) and the noise / vibrations are both gone. It's been over a year since and everything is fine by date.

Make sure to use "interlock" type flex sections (which is braided mesh on outside and harded "corrugated" section on the inside) as they are stronger / hold longer than cheaper all-mesh flex sections which are also available.

[ValidatedS4]

It's flex sections failing as said above.


I was getting the same vibration / noise on my OE exhaust at 1000 RPM exactly since purchasing my car (got it pre-owned). Gutted the cats (retaining otherwise OE exhaust) down the road but noise / vibrations remained. In about 6m thereafter changed the flex sections (there was an audible leak from them) by cutting the OE ones out and welding the new ones in their place (same size as OE ones) and the noise / vibrations are both gone. It's been over a year since and everything is fine by date.

Make sure to use "interlock" type flex sections (which is braided mesh on outside and harded "corrugated" section on the inside) as they are stronger / hold longer than cheaper all-mesh flex sections which are also available.

Do you have an example of the replacement piece you put on? I’m hearing this when I blip the throttle at a drive thru or near walls.

[-leman-]

Don't have the exact dimensions, sorry. Maybe someone here will share. Re. "interlock" type you may have a look on the flex pipe here (you may see it's not all mesh - the inside part is corrugated metal pipe): https://www.alibaba.com/product-deta...533400231.html

FWIW your issue (if it's only sound, not vibration) could be just an exhaust leak from one of the joints, so I would start by checking these. Mid to back section connection often develops leaks, if that would turn out to be the issue in your case it could be fixed by just replacing the clamps.

[davesxx01]

Interesting thread! My car, '12 S4, 64K miles, stock exhaust, vibrates my car right at 1K rpm when slowing down or slight reving in P or N and has been bugging me. Guess I'll look at the flex pipes!

[dmill19]

have the exact same issue. glad to see this is a "normal" and non troubling issue. i dont see this in anyway really stunting the performance of the car. just to me im really odc and all the little things bug me. so hearing this noise tends to drive me nuts. i planned on just doing a new exhaust system anyway. i had a b7 s4 and i need this v6 to give me the feels my v8 did.

[HOUs4]

I'm glad you bumped this thread. I just noticed this sound/vibration after installing my aftermarket exhaust. I never noticed it while stock.

[Starman17]

The mesh on my flex pipes was woven like a fabric rather than that criss-cross pattern above, but I noticed it had a few completely loose/broken wires dangling in it and removed them...that fixed my rattle. Worth a quick check before replacing the whole thing!

[montyjack]

Hey guys!

I found numerous threads on this topic so I didn't want to start a new one, just reopened an older one.
New here, but reading these forums quite regularly. I am experiencing the same issue on my 2013 S4.

From what I read and understood, majority of you are saying this is an issue with downpipes - or more precisely the flex pipes.
Engine is damn smooth and this rattle/vibration just makes it unpleasant to drive at city speeds where you frequently slow down or stop.
Does anyone have newer experiences in the past few years, as most of these threads are years old?

Currently I am thinking about these options:

a) replace by OEM downpipes
Feel like this is a safe option, however quite expensive one.
Also I want to get some small extra portion of sound from my exhaust system in the future and maybe this is just a redundant step.

b) replace by AM downpipes
There are plenty of options out there, some are not street legal and I am obviously not looking at them.
Any of you have some recommendations, at what brands should I be looking at?
I dont want to make the car sound way off, I rather enjoy the subtle-ness of the stock system, so nothing too extreme.

c) changing flex pipes
This seems like economically the best option, however this would need a good mechanic + welder that would be able to custom fit it.
The question still remains, is anyone 100% certain that the rattle is caused by the flex pipe?
If yes, any recommendations suitable flex pipe replacements?

d) (temporary) increase downshift rpm point
Just an idea - whenever I am driving in the city for longer, I usually just switch to manual or S to prevent entering the rpm range. Then the only time it actually hits this rpm range is when I go to full stop.
But if the regular drive mode would've downshifted at lets say 1300 rpm instead of 1100-1000 rpm (like it actually does in S).
My question is, is this even possible to do / worth looking into or trying?
In any case I think the D mode is keeping extremely low revs at some speeds. Sometimes when I'm driving at 50-60km/h through the city, the car shifts to 5th even 6th gear...Then I suddenly have to slow down and 3-4 downshifts happen at that damn 1000rpm range and the whole car vibrates annoyingly.

I appreciate anyone who gives their insights / ideas / opinions on each of the options, and/or gives another plausible solution.

[NiklasStrom]

Its worth to check if the exhaust is touching somewhere under the car. I had som crazy vibrations and ratling in my car, turned out the bolts for my tips was touching the back side of the diffuser. It was so bad it had actually started cutting into it. I mounted the exhaust in august, and first now the last few weeks it started ratling.