Knock at idle
 

I have a 2003 93. It is my wifes daily driver so I only heard it the other day when I borrowed it.
It is making a knocking noise at idle mostly when cold but not limited to when it is cold. It will come and go at random. Does not speed up or change pitch when gas is applied. When driving down the road or revved it does not make the noise. It seems to be coming from the turbo area maybe. It does not idle rough. It has good power. The noise is the only thing that lets me know there is a problem.

If anyone has see this please let me know.
Thanx
David