Did you try going to about:config, searching for keyword.URL and seeing what's there? If you go there, you will see which search engine is set, not in a special little bar, but in the navigation bar. Then you can eliminate the little bar (sorry for my non-professional language) with the search engine and use the navigation bar the same way. You only have to change the value when you go to about:config and search keyword.URL. Then put this:


Hope it's useful!