Replaced master cylinder and bleed brakes. The brakes seem fine when the car is off, but when I turn it on there is a sucking noise like a vacuum leak coming from the brake pedal and brakes become squishy. Brakes operate very poorly. The brake pedal also pops - I am assuming it is actually the master cylinder - when the pedal is depressed all the way. What the heck is going on? Please help.

 

bleed the system with the engine running if the problem continues then look at other options

 

don't forget to activate the rear weight sensor connected to the rear Axel " cant remember the name lol " but if you don't you cant bleed the rear breaks