strange smell from Bedroom

[al perna]

well it's back ,

On the climb out of Indo to Las Vegas a strange smell returned that I thought was the muffler , but with it replaced the smell remains.

I would like to find it now prior to doing some real climbing in a few days on the way to Denver . On a walk around the coach and in inspection of engine compartment there is no smoke or smell . what ever it is , only starts after all long climb. So I read maybe the insulation in the bay but would nt that also smell out side ? Any and all ideas will be followed up on .