alright.. i have another thread in the s4 section but havent been able to locate the information that i need. 2000 b5 s4 6sp.... 93 octane apr tune in use.. the boost comes on pretty hard in first gear but i hear a boost leak and i dont get any higher than 15 psi in first gear. then on to second gear and the boost peaks out at about 21 or 22 psi.. the throttle even cuts out.. but still on occasion i can hear boost rustling out somewhere.. then the same thing in third and fourth but i dont hear any boost leaks...but the boost is pegging pretty high.. and the throttle cut back is noticeable.. as soon as it cuts back it drops to about 15 or so before it levels out at 17 or 18... did a pressure test by closing off the two rubber inlet tubes in the front of the engine, the ones that go over the valve cover gasket and have a smaller connection to the diverter valves... then i took out the boost pressure sensor in the tbb and installed a make shift tire valve stem that seals properly.. and just watched the pressure rise as i used an air chuck to supply pressure. it seemed that most of my pressure was being lost out of the accordian style tube that connects to the back of the y intake pipe.. its part of the pcv system i think. i could then block it off with my thumb and i also located a leak around my number 3 injector o-ring.. but thats another story..

my question is .. is there supposed to be pressure bleed off from that accordian style hose? or have i located a problem? im gonna fix my injector o-ring and then test drive again, unless i get other information on the pcv system.. any response or info would be awesome.. thanks guys and gals..

 

There should be pressure bled off there. Under normal conditions that is on the suction side of the turbo and provides vacuum for the pcv system.

 

i'm having a hard time trying to understand the problem.

you believe you have a boost leak...?

cause it only reaches 15 psi in first... but goes to 22 psi in the rest of the gears...?

do you have an aftermarket boost gauge...?

if you had a boost leak you would notice other problems than that you boost gauge reading low in first gear... cause where there is a boost leak there is a vaccum leak at idle.

 

yep. and im getting about 18 inches of mercury at idle on a warm engine when it should be closer to 20. and i do have a vacuum leak, and a boost leak.. out of the # 3 injector .. its leaking out of the o-ring.. and when going in any boost over 10 psi you can hear a boost leak from under the manifold.. take some 409 and spray to locate some bubbles or what ever and all around the injector o-ring to the manifold... and spitting and sputtering from around the oring .. so ill replace that and see how the car runs...you cant hear the vacuum leak as well...