@Xulfiqar , may you please share some of your experience on my query ,i am listening that hissing sound since many days when engine goes to its optimal temperature,fuel everage has dropped dramatically . I
have checked the brake booster and adjacent hoses all OK , cant foresee
about booster itself but with a faulty brake booster your brake pedal
pressure should go down that's not the case here ,brakes are perfectly
OK,in addition ,if i pinch the brake booster vacuum line with fingers idle does not sustain . Source of the sound is surly is somewhere under the driver side
wheel arch or the driver side strut mount and brake booster side . It looks like a vacuum leak , already have observed the vacuum line around intake ,nothing wrong found , tested with the carb cleaner spray onto intake ,idle remains constant . Idle is perfect ,pick up and drive is perfect too .