FL S8: Airfilter box gone Boombox

[SilverS8]

Hi all.

Just spent an hour listening to the engine while idling

I've always since i bought the car 2 yrs ago felt like there was a strange repeatedly *thump* when listening closely to the engine while bonnet is open.
While doing a check for intake leaks regarding the 17549 code by emptying a bottle of Start Gas on all places where it would be possible to suck some in.( no chance there is any leak..) i noticed after removing the cold air intake pipe that the boombox *thump* comes from inside the airfilter box..

Anyone else experienced this?

From the good old days i would call this backfire caused by the timingbelt not in the right position but since car runs perfect it has to be something else. only issue is "auto-reving 3 times to apx 1800 rpm at coldstart before setling down. This started with the 17549 code appearing.


So, any good ideas gents?