hard to say with out seeing the bin file your car is running. if the local guy just flashed a tune he made in there it might not have the fans set to a lower temp. meaning he should have read your pcm, then worked on that bin file, and reflashed it. of course i was not there, so idk what went down.
still got the zzp pcm with its tune? pop it back in if you do.
you can also pop open the t stat, fill the engine with coolant via the t stat lim hole, this will make damn sure theres no trapped air.
my old engine also ate coolant. would eat a couple inches a day. no leaks, nothing out the tail pipes i could see or smell. i dumped in a bottle of blue devil and dont ya know it stopped eating coolant. blew that engine up, new engine is 100% normal. so something was cracked inside, maybe a head or something like that. head gaskets looked just fine too.
