I installed new rear calipers on both sides, new pads on all four wheels, and bled brakes with engine off, then with engine on, two times each. The pedal is hard when the engine is off and extremely soft when running. It can be pushed to the floor with little effort.
I'm aware that there is probably air in the system somewhere, but I've bled through a significant amount of fluid with no bubbles coming out. Would air trapped in the ABS affect the pedal feel? Are there other possibilities that I should check, or is the best course just to keep bleeding?
The vehicle is a 2002 Buick Lesabre.