I found a
solution to
my Galaxy S4 not pairing properly to my Ford Audio
Tick the first option in the Galaxy's Bluetooth settings -- I THINK it's "Make my device visible to all near by Bluetooth devices"...something like that anyway.
Once this option's ticked, you'll notice a little countdown timer appear....go ahead and re-pair your Galaxy to your Ford Audio before the timer runs out (don't worry, the timer goes on for 2mins).
This worked for me. I drive a 2011 Ford Fiesta (with standard head unit and audio system that the car ships with -- not sony). Be4fore, the two devices would connect, but only for a few seconds and then the ford audio would automatically unlink...now they stay linked, which is good because i signed up for a 2 year contract with this phone only yesterday and seeing this problem made me wanna go run over kids and elderly -- not really