I have a boost problem with my '07 Mini R56 MCS. It runs fine with boost when the engine is cold, but when it gets to operating temperature the car loses boost and eventually will go into limp mode (yellow half engine icon on tach). When I let it stand overnight, it will still display the icon at startup, but runs fine. After it's warmed up the boost disappears. I can hear a 'whistling' sound from the top of the engine and there is a strong vacuum on the oil cap and dipstick. Could a leaking PCV or valve cover be the issue here? Because plastic expands when hot, loses boost through the leak? When I pull the rear PCV hose off the valve cover (the one that goes to the intake manifold) the idle goes up to 1900rpm. Who knows what could be the issue??
