First of all kudos to L. based on my article here: http://obiee101.blogspot.com/2011/07/obiee11-how-to-use-log.html he pointed me out how to set the log level in the rpd in 11.1.1.5.
Open the rpd in online mode and select manage > Identity
Select the BI repository and users tab:
Don’t be fooled (like me ) the users are already in the RPD.
Select Action > Set Online User Filter
Enter a *
Now you can set the loglevel:
Till Next Time