Hello again ,
I think, I found the cause of the knocking sound at idle. It turned out that
the knock sensor wiring change was not done properly by the service center.
Instead of changing the polarity of the signal, they swapped 2 knock sensors.
The correct way to do the wiring change is shown in the following picture
See message #51
http://syclub.ru/showthread.php?t=7796&page=3