Thanks PaulS and al1fch.
After a 1 minute thinking.. I've found a solution.
I have a thread to listen bluetooth stream... but this thread don't have sleep time. It's so fast to listen arduino.
Maybe isn't a perfect solution, because still data are broken, however much less (~10%)
I'm using 9600 baud rate. My Android 2.2.
I've tested with BlueTerm too with same results.
Soon I will post here the source code.
thanks