Rough idle with humming, drone, ticking sounds (with audio/video)

[ee128174]

Greetings,

 

My 2012 Cayenne V6 (base) runs fine overall.  However, during idle the engine sounds rough.  I have recorded a sample in case it helps.

 

Some additional details:

- I hear the sound both when the engine is warm and cold

- It happens during idle while in gear and somewhat less in neutral

- Car has 43000 miles and is still under warranty

- My driving style is conservative, i.e., I don't push it much (most of the time...:)

- I use premium gas and had serviced recently

- During lat major service the diagnostic computer did not show anything abnormal

 

The linked video has a slow motion clip (120 fps) that shows the sounds details.  I can discern 2-3 patterns:

- Ticking sound of constant frequency (about 2 times/second)

- Pulsating sound of same frequency as ticking, but at lower pitch (like drone) 

- Some background humming 

 

Any suggestions on what this could be?  I have seen other postings where piston scoring, sticking lifters, or EGR may be the cause.  I have an appointment with the Porsche dealer tomorrow and would like to help them root-cause this quickly.  Greatly appreciate any insights!

 

Thank to all in advance!

 

Elias