Hello, I'm new on blender and when I export my file to an .fbx file and import it in esenthel, there are some faces that are really wrong and others that dissapear. It looks like there are some gaps in the object, really weird.
I don't know what to do now, so is it possible to help me?

Hi, maybe it depends on the options that are set when exporting to .fbx.
Myself I use the plugin for blender to export to .dae (collada) format, always worked fine so far

I also get the same thing exporting to FBX from Blender. DAE works fine as Ezequel says.

Hi, I've exported an object to .dae, but I still got the same problem, there are gaps in my object and I don't know why. Maybe the problem is with my faces in the .blend file?

Maybe some of your polygon normals are directed inward.
In Edit mode test with select all polys and the Ctrl+N (Normals Recalculate Outside)

Yeah, I've just found this method also on a forum, tried it out and it works!!! I'm very happy, thanks for the reply.