Where did you connect the other end of the vacuum line from the vacuum booster? Is the plastic check valve installed facing the right direction? There is an arrow on it to show which direction it faces. shermanmartinez@hotmail.com Just got the brake booster re-installed, w/ new 528i master. Whether the engine is off or on, the booster won't hold a vacuum. The pedal sinks to the floor, and air blows out the carb. All vacuum ports are plugged. What the hell is happening?