Miltek Cat Back Exhaust Drone

[carlos50]

Hi all

The Miltek cat back exhaust on my new to me 2016 RS6 is a bit of a nightmare on my motorway commute, constant drone at motorway speeds, yes sounds nice when getting on it but at cruising speed its just drone, lift off it goes, then light throttle again and drones again.

Not sure if its resonated or none resonated car is lowered so its hard to get under it. Does drone suggest none resonated and if so will adding the Miltek resonated centre section remove the drone?

Thanks
Csrl

[audiBond]

Have you checked the valves are opening and closing properly in different drive modes?

I had to replace both rear sections of my miltek system last year at a cost of £2.5k, because the valves were stuck, one side open, one side closed. Warranty only applies to original puchaser of the exhaust, so had to by two new rear sections. Fixed the problem and car sounds nice and quiet on the motorway in comfort and shouty and loud in dynamic or individual.

[carlos50]

Hi, I haven't, it doesn't spit and pop in Comfort so I'm assuming all is good with the valves, but the motorway drone is a consistent feature. My R8 V10 had a Miltek without any valves and the experience was the same, drone on the motorway, I sold it as it was too much on a 40 minute commute, twice a day, every week day.

[Tadass910]

Hi all

The Miltek cat back exhaust on my new to me 2016 RS6 is a bit of a nightmare on my motorway commute, constant drone at motorway speeds, yes sounds nice when getting on it but at cruising speed its just drone, lift off it goes, then light throttle again and drones again.

Not sure if its resonated or none resonated car is lowered so its hard to get under it. Does drone suggest none resonated and if so will adding the Miltek resonated centre section remove the drone?

Thanks
Csrl

When you start car try open valves by choosing dynamic mode and go to your exhaust and check if valves open, then try comfort mode and see if it’s closing properly? I had also issue with one side rear muffler valve was not closing properly, if you drive short distances sometimes carbonate not burns, also it may be some dirt stays in, and valve can stuck, after driving longer distances like 100km my valve fixed itself, I also spray on top of it wd40 so valve is lubricated

[carlos50]

Had a bit of a look under, being lowered its hard to get a good look, but I think its the none resonated version, theres no centre silencer the pipes run from back boxes to front pipes.

Is that likely to be the reason for the drone?

[Tadass910]

Had a bit of a look under, being lowered its hard to get a good look, but I think its the none resonated version, theres no centre silencer the pipes run from back boxes to front pipes.

Is that likely to be the reason for the drone?

Try checking what I wrote, check your valves

[carlos50]

I checked, both seem to be open all the time. I looked in with the car turned off and last used with engine sound set to comfort, and both are open, started the car and turned Drive select to Comfort but the valves didnt close, turned it to Dynamic then back to Comfort and still no movement. I could feel a wire going to the valve control so assume theyre connected which would suggest theyre both stuck open.

Is there a way to release them, cars only done a few thousand miles in the past few years so maybe salt and dirt, plus the obvious coking got in there?

Maybe I change it back to factory?

Thanks
Carl

[carlos50]

Some research suggests then being open at idle & parked is normal, engine was cold too, so i dont think it means anything then being open today?

[carlos50]

[carlos50]

Checked again this morning and valves both close no problem so I think its just the none resonated centre section thats causing the drone.

Thanks for the advice

Carl

[Tadass910]

Hello, if valves closing in comfort and open in dynamic then you exhaust works just fine, and it’s none resonated Miltek seems to me, I also own that exhaust, when in comfort and on a highway everything fine no drone, only when dynamic mode I hear then some drone.

[carlos50]

Thanks. Im in comfort and have some drone.

I just put up a new topic, i found a cream tube hanging down on the drivers side rear wheel just inside the rear bumper behind the wheel. If the exhaust flaps werent working Id be saying its a vacuum line but since they closed on their own this morning they cant be disconnected.

Thanks again

[Tadass910]

Thanks. Im in comfort and have some drone.

Well that’s normal, if your valves closed in comfort nothing more you ca do here

[carlos50]

Turns out i have the front pipes cat bypass pipes too, so that probably increases noise aswell.

How much does fitting the resonated centre section reduce the noise, and is it still better than the Audi “Sport” option, i have the original and ponder putting it back to the Audi sport version but dont want to regret it

Thanks