so i began taking everything apart to pinpoint my buzzing noise after the car is off.. and i know its my vacuum pump but what is it doing???
i know its pumping vacuum, but why???? why do i need vacuum when the cars off???
this leads me to my main question.... does the booster need to have vacuum when the cars off????

if it does i need to replace that 3 way valve system.

and if anyones got alldata??? please can you find out about this whole system? PLEASEEE!!!!!!