850 Turbo Hissing under 5lbs pressure

mrscottg89 · Post by **mrscottg89** » 19 Dec 2011, 22:19

At 0-5 lbs of pressure, acceleration above 40 i get a fairly disstinct hissing from under the hood I get it only with acceleration from what I can hear for now. It hisses and when left off the gas I get a psst finish, I looked up all the similar postings and some close but none had the exact same issue's. My car is a turbo, has all hoses connected correctly from what ive seem, could this be wastegate or recirc issues seals Something any knowledge would be good, Could this just be what comes from the turbo in super cold weather. I'm wondering because it hadnt been doing this recently until I ran into some issues with the heater core and pcv replacement.

shegarty · Post by **shegarty** » 21 Dec 2011, 13:07

its possible that you have a vacuum leak - is the performance compromised? check the three main vacuum connections that come off the turbo, tracing them back to origin on the regulator attached to the air box and the main vacuum tree on the manifold - its likely that a line was disurbed/pinced/torn or otherwise damaged during your recent repair work

Post by **vjaneczko** » 21 Dec 2011, 13:50

I had a nasty hiss this fall and it turned out to be the rubber elbow on the fuel retun line had a split on the underside so it was hard to spot. I had to stick my head under the hood and listen for the source.

I didn't get the 'psst' finish you mention so I'd be looking at the 5 intercooler hoses, especially the IAC hose with it's 'third arm'.