Changed Master Cylinder. Pedal still going to floor?!

[///Monster123]

My understanding is that you have air trapped in the ABS module and need to run the ABS bleeding function from the Foxwell service menu.

E53's also like to rust the brake lines that are directly under the driver seat. Check there for leaks in your system.

I also feel you on being frustrated. Go hammer some big nails into a stump or chop some wood. Maybe even go to a batting cage for a little session. Don't take it out on the old BMWs, they're way too fragile.