986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - Hissing on throttle tip-in; vacuum leak? AOS? Normal?

Toddyus · 05-30-2023, 03:03 PM

Had the engine cover off and there is a noticeable hiss on throttle tip-in. Sounds very much like a turbo blow-off valve. Is this normal? Could it be a vacuum leak, and if so, is there a common place to look? I also tested the AOS with a manometer. At temp, readings are about 5.25 in/H2O range and with revs hitting about 3k rpm (not at load), reached about 7.25 max. Seems normal range, but could it be the AOS?

Any insight will be appreciated.

05-30-2023, 03:03 PM	#1
Toddyus Registered User Join Date: May 2016 Location: Cleveland, Ohio Posts: 5	Hissing on throttle tip-in; vacuum leak? AOS? Normal? Had the engine cover off and there is a noticeable hiss on throttle tip-in. Sounds very much like a turbo blow-off valve. Is this normal? Could it be a vacuum leak, and if so, is there a common place to look? I also tested the AOS with a manometer. At temp, readings are about 5.25 in/H2O range and with revs hitting about 3k rpm (not at load), reached about 7.25 max. Seems normal range, but could it be the AOS? Any insight will be appreciated.