85S Hissing sound or high pitch sound under center intake
08-29-2010, 12:11 AM
#16
Rest in Peace
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In this case i have to ask why, if it is under the intake, it is going to have to come off and every thing replaced any way.
08-30-2010, 10:58 PM
#19
Burning Brakes
If the idle is OK and the noise increases with rpm you are probably looking at an intake leak on the air filter side of the throttle. Any significant leaks after the throttle go away with increasing rpm and tend to cause the engine to stall or run rough at idle.
Unfortunately it can be pretty difficult to diagnose anything under the organ pipes because as soon as you rmove parts to gain access the engine will not run. It sounds like it might be large enough to find from a simple visual inspection once you pull the center T.
Unfortunately it can be pretty difficult to diagnose anything under the organ pipes because as soon as you rmove parts to gain access the engine will not run. It sounds like it might be large enough to find from a simple visual inspection once you pull the center T.
08-30-2010, 11:02 PM
#20
Team Owner
it is also quite possible that if you had one of the plenums off then one of the rubber seal hoses isnt fully capturing the opposite side of the intake , if you remove the plenums then you should be able to see a deformed rubber hose and or clamp
08-30-2010, 11:19 PM
#21
Rennlist Member
Its possible, too, to have one of those little vac hoses loose / off the throttle body.
And a break in the idle valve hose.
Also the crankcase vent hoses on the passenger cam cover are notorious for failure.
There is a bunch of stuff under there, after all.
This is one of the most effective tools in my kit for digging around inside these organ tube cars because you can backlight stuff:
http://www.amazon.com/Streamlight-65...ref=pd_cp_hi_3
And a break in the idle valve hose.
Also the crankcase vent hoses on the passenger cam cover are notorious for failure.
There is a bunch of stuff under there, after all.
This is one of the most effective tools in my kit for digging around inside these organ tube cars because you can backlight stuff:
http://www.amazon.com/Streamlight-65...ref=pd_cp_hi_3
08-31-2010, 05:26 AM
#22
Drifting
Whatever it may be, at this age, if it hasn't been done already, the car is due for an intake refresh.
I've had the paper intake gaskets on mine for over 50K miles and they're working fine. I think Porsche is the only party that finds the crush metal gaskets to be advantageous and this is only because they cost so much more.
I've had the paper intake gaskets on mine for over 50K miles and they're working fine. I think Porsche is the only party that finds the crush metal gaskets to be advantageous and this is only because they cost so much more.
