You should know if a map has navs.How?Survivor bots would follow you where ever you go.These maps are usually from Counter Strike:Source,which l4d2 uses that games system of navs.So if that is the case,you shouldn't be reading this guide.Or you can,I don't care.Anyway on to the first step!

If you've read the last guide I made,you should know how to port gmod maps into l4d2.If not,go check it out.Anyway,load the map up by typing this into the console:map "mapname" and it should load.Once in the map,make sure to have cheats on,type in the console:nb_delete_all,director_stop,z_debug 1,nav_edit 1,noclip(this command is optional).Once you've done all that,the bots should be gone.Good.You should also notice your cursor has changed.That is what you will use to mark walkable areas in the map.Then after that,point at a place in the map,type in console:nav_mark_walkable.It should create a purple "thing".That puple "thing" is now conidered a walkable for zombies and bots.To see what area it covered,type in console:nav_generate incremental.You should then how much that "thing" covers.Keep doing this if you want the whole map to be navigatable.Once you're done,type in console:nav_analyze.There your good to go!Type nav_generate in the console and it should save.That's it!