I recently bought a B18C1 powered Civic with a JR Supercharger. The car seems to have some pretty serious compressor surge and an unsteady idle.

Is the compressor surge related to the unsteady idle? or is it just something that all SC'd cars do?

Also..The only thing I can think is causing the unsteady idle is a vacuum leak somewhere, but my boost gauge shows a good 18-20inches of vacuum at idle and I replaced all the gaskets just in case...

Any idea's? I get anywhere from a 100 to 250rpm swing during idle...

 

The rpm swing at idle could be caused by a dirty idle control valve

 

Good point..I'll take a look...
Where is the IAC valve located on a SC'd car (no stock manifold)