This document will provide the steps necessary to enable verbose tracing for the FIM Portal.
FIM Portal Tracing is enabled/disabled via the Windows SharePoint Services 3.0 Web.Config file. ( C:\Inetpub\wwwroot\wss\VirtualDirectories\80\web.config )
If you made the backup copy of the web.config file, then you can rename the tracing file to web.config._TracingEnabled. Once you do that, then rename the backup copy back to web.config. If you do this, then you should be able to easily toggle back forth
to enable/disable tracing.
Anytime you change the web.config, then you will need to execute an IISRESET from an Administrative Command-Prompt.
How to enable FIM Service Tracing
How to configure FIM Portal Tracing
Enable Tracing and Viewing Trace Logs