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Josh · Posted: Sat Dec 01, 2012 5:17 pm Post subject: Signs of wastegate creep

Hi

I have been struggling with the sealing of my air intake between the turbo and intake manifold. I have an aftermarket boost gauge installed. My problem is that when i drive the car the boost gauge shows the car going out of vacuum and sitting at 'zero boost'. So its no longer under vacuum but its not boosting ether. This might be the wrong terminology but its as if the cars intake pressure has reached equilibrium.

If I continue to accelerate relatively hard the boost gauge wont move and stays at zero. Eventually at a certain rpm (WOT) the boost gauge jumps over to full boost. I was wondering if this could be due to waste gate creep? As surely an air leak would have to be extremely large to hamper the boost to such an extent.

The boost gauge is relatively new so don't think it would be faulty

Feed back would be highly appreciated!
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Porsche 924 turbo 82
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Carrera RSR · Joined: 08 Jan 2010 Posts: 2296 Location: Somerset, UK

Depends where in the intake system you have your take off for the boost gauge. Before or after the throttle body or which vacuum line. It makes a difference to the guage.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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ideola · Joined: 01 Oct 2004 Posts: 15544 Location: Woodstock IL

The boost gauge must be plumbed in AFTER the throttle body. If you have a S2 931, this is easy to accomplish by tee-ing off of the line that feeds the DITC. There is a banjo fitting at the back of the intake manifold, and you can easily tee into the line there. If you have an S1, just drill a hole in the intake manifold and tap it for 1/8 NPT. Then install put a 1/8NPT-to-hose barb fitting, and use that to tie in the boost gauge.
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erstwhile owner of just about every 924 variant ever made

Nein37 · Joined: 29 Dec 2009 Posts: 513 Location: New London, CT

Maybe the recirculation valve is stuck opened?
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1981 931 CGT replica, OEM CGT intercooler, .8 BAR WG spring, GTS Headlights, Innovative Wide band A/F, A/C delete, 16" Fuchs, Weltmeister 200lb lowering springs, Bilstein HDs front, Koni Sport rears.

Cedric · Joined: 27 Aug 2004 Posts: 2539 Location: Sweden

Smoothie · Posted: Mon Dec 03, 2012 12:28 am Post subject:

If it's not stuck, the recirc valve should make a clack sound whenever the throttle is opened/closed. That's the quick-easy test.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

kcoyle · Joined: 15 Jan 2011 Posts: 712 Location: Long Island, NY

Stupid question and I don't know where you gauge is installed, but is the vacuum line to the gauge kinked or pinched anywhere?
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1982 931- Stock with MBC at 8psi

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