1. I have not heard from John since I lived in Taipei.
2. I have not heard from John since I have lived in Taipei.
3. I have not heard from John since I came to live in Taipei.
The time span involed in the above sentences is the same.
But sentence #1 means that I no longer live in Taipei "now."
#2 means that I still live in Taipei.
#3 can mean either.