i recently purchased a 1990 740 turbo, the brake pedal was very low on the car so i figured needs a master cyl. I purchased one from the local parts store, bench bled it, installed, no change still low pedal. I took it back, purchased a "new" master cyl. installed, no change. Ive bled all four wheels, installed new front pads ( needed them ), let it gravity bleed, no change. With the car not running i have a strong firm pedal, wont leak down. When i start the car my pedal is low and it will slowly leak down if i hold press. on the pedal.

I decided to bleed it at the ABS unit and the pedal got better but not where it should be. I think i have air in the ABS unit. Ive read theres a way to bleed the car with ABS without taking it to a shop and hooking up to a computer to bleed the ABS does anyone know how to do this ??? Any other ideas what my problem could be ??