Vladgladlad

Hello,

I have the following problem with my Audi and none of the services that checked the car in the past month managed to solve it. So if anyone of you guys have some thoughts on this, please share them.

I can hear a little bang noise almost each time I brake to a complete standstill or I accelerate gently. It usually appears around 2-3 km/h only once but sometimes it appears in 2nd gear at about 15km/h, also once. It also appears each time the engine stops (through start-stop or manually). The noise is almost unnoticeable when music is on at about 15-20% volume.

The noise can be replicated easily in hill start conditions when accelerating slowly. The car makes it every time in such conditions.

Another thing I noticed is that when the Autohold function is activated the noise disappears when departing from standstill but is still present at about 15km/h and when I switch off the engine.

The computer diagnosis shows no errors.

The car is a 2012 Audi A7 3.0 TDi with no modifications.

Thanks in advance.

Vladgladlad

Hi guys,

The more appropriate description of the sound is a click or knock. The sound is only produced once (immediately after departing or at 15 km/h). While the speed of the car is above 15 km/h the sound does not appear. I listened closely and I do not think the sound is somehow covered by the engine noise at higher speeds.

Any idea would be appreciated.

Thanks!

tenspeed

I would see if the engine is moving with torque applied. There have been a few threads about failing motor mounts.

Open the hood, stand off to the side, have a trusted friend start, stop, put it in gear - see if anything is moving or if you can hear where the noise is coming from. Did I mention to stand off to the side?

Vladgladlad

Thanks for the advice. Really appreciate it. Actually the motor mounts of my car were replaced 1 month ago and immediately after this the noise appeared, so they could be the problem. The only thing I cannot really understand is why this happens even in N at the exact same speed (15 km/h).

tenspeed

Take it back and have them check their work. Could be as simple as a loose bolt or perhaps a bad mount.

Vladgladlad

I will definitely do that and I will let you know.

I am still trying to grasp how electrical motor mounts work and what I could gather is that they are dependent on the RPM of the engine, not on the speed. Therefore, the sound makes no sense because it does not appear when revving the engine in N, but is present when I put the car in N and let it slide until it hits 15 km/h.

Nevertheless, motor mounts is the most plausible solution so far, so thanks again.

tenspeed

I am new to electro-magnetic motor mount too. I would guess that the operate equal and opposite to dampen engine vibrations. The mounts my be good and the bolts holding them are loose or something that was removed was not replaced correctly. Since the problem started after the repair, it's a good place to start looking.

Here's a couple of motor mount charts

Vladgladlad

Thanks a lot for the diagram. It is very conclusive. I am pretty sure now that engine mounts function depending on the speed of the vehicle. I will take the car to the dealership and keep you posted. Maybe I find out something worth sharing

Vladgladlad

So I had the mechanics check the engine mounts and they are ok. The also checked the brakes which are also in good condition.

I uploaded a video with the problem. The knock comes from behind the MMI (engine area), not from the sides.

Vladgladlad

So quick update after 1 more visit to my Audi dealer. Maybe it will prove helpful to others.

They checked the engine mounts, transmission mount and all seems fine. They still cannot figure out what is causing the noise. Work in progress...