It's because you haven't correctly compiled the map. The folder Documents/Beamng.drive/levels holds your saved map files, and it loads the modified version when you start up the map. That's why it loads ECA, becuase they don't have the actual map files you made. To do it correcly, go to Documents/levels/YourMap and move all those files into YourMap.zip/levels/YourMap, and delete the remaining folder.
