I have a 2000 GTP with 185k miles. It has developed an engine noise that makes an "ERCH" sound about every 1.5 to 2 seconds at idle. the noise will speed up when the RPM is increased. The noise seams to be coming from somewhere around the #1 cylinder to the middle of the intake. I have taken off all of the belts off and started the engine and it makes the same noise. I originally thought it would have something to do with the timing chain since the noise frequency was slower than engine RPM speed. If it was a bearing I think it would be a lot faster or continuous. Any help would be appreciated.

Can you shoot a video of this and post it to Youtube?

I currently have it disassembled down to the timing chain. There is no significant wear or slack in the chain.

Could have saved you the work.

Engine is back together. Attached is the you tube video of the car running without the belts on.

That is a really weird noise. A noise I never heard before.

Time to get the auto stethoscope out and poke and prod.

did the stethospoce and it is the loudest around the #1 cylinder and under the supercharger snout on the manifold.

Your balance shaft bearings are right under the snout.

The least amount of work to inspect it would be removing the */C, and the LIM. Then you should be able to grab the balance shaft and check for lateral/axial play in it.

Worst case scenario, it is possible to completely remove the balance shaft.