Komodo php autocomplete didn't work for me, too.
My situation might be different, but I'm sharing for the next Googler to visit.
I installed Komodo before php5. Whoops. Installing php wasn't good enough, I had to also delete the config files in ~/.komodo-edit
(or whatever folder it created).
That still wasn't enough, I also had to delete the ___.komodoproject
file I was working on as well.
Then I was awed by Komodo's awesomeness.