I have a 1997 D16Y8, fully stock. Timing belt was apparently done early this year... By a low quality mechanic (2 wiring harnesses were left to rub on the belts, A/C pres. sw., and CKF sensor wiring) Anyways, I just bought the car and I haven't checked anything yet. I start up the car when it's cold, idle will begin to slow, it reaches 1500rpm. Now at this point, it starts to make a low noise that's hard to describe, but is regular and goes with the engine speed (1400-1600) I'm thinking the timing belt may be loose and it's rubbing a cover, but I don't know for sure... I haven't checked. If anyone else thinks this sounds familiar, or has fixed something like this before... let me know.

 

The timing belt on 96 - 00 civics y7 and y8 motors will make a whiny noise at around 1000 - 2000 rpm if they are too tight. In fact in around 99 Honda changed the specs on timing belt tightness to correct this problem since some buyers were complaining. I loosened mine as Honda suggested in the shop notes and the problem went away. Just a thought.

The noise usually comes from the upper cam sprocket.