Clover EFI installer log - Sat Jul 18 20:37:47 CEST 2015
Installer version: v2.3k r3241 EFI bootloader
======================================================
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *320.1 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS MacDiver                319.2 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *16.4 GB    disk1
   1:                  Apple_HFS THEOTIX OSX             16.4 GB    disk1s1
/System/Library/Extensions/msdosfs.kext failed to load - (libkern/kext) operation/kext not allowed at current boot level; check the system/kernel logs for errors or try kextutil(8).
mount_msdos: msdos filesystem is not available

ERROR: can't mount ESP partition (disk0s1) !
Check that the partition is well formated in HFS or Fat32.

To format as HFS use command like:
sudo newfs_hfs -v EFI /dev/rdisk0s1

For format as Fat32 use command like:
sudo newfs_msdos -v EFI -F 32 /dev/rdisk0s1