I put a new left rear caliper in my Civic Si (92) the other day, with new pads for rear. I bled the caliper several time, drove it and bled it again, but I still have a mega long brake pedal. No idea why, everything seems ok, and everything was ok before I put in the caliper, other than my ebrake on that side didn't work. Its been a few days, I checked all 4 calipers for leaks, and re-bled the entire system, problem is still there. I have no idea what is going on, I am wondering if the new rear caliper is faulty, although I doubt this, no leaks, ebrake works fine, brakes actaully work ok, just the pedal has long travel.
Anyone have any ideas? Yes, I searched, alot.

 

Seems like everybody's having brake-bleeding trouble lately...

Bleed all 4 again, & let LOTS of fluid thru the rears. My GUESS(!) is you bleed several ounces at the wheels, but there's still bubbles somewhere in the lines to the rear. You think you're done, you go for a test drive, the pedal is still soft. But now the bubbles have traveled back towards the master, & each time you bleed the bubbles only make it halfway to the rear calipers.

Since you put in a new caliper, you could also try rapping on that caliper to dislodge any bubbles that are hanging onto the walls.