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mark houghton mark houghton is offline
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Join Date: Jul 2008
Location: Central Washington State
Posts: 3,860
We need to see some pictures of your groovie new ride. The pictures help grease the wheels for the diagnostic help you'll receive.

I think Jacob hit the most probable points to look for boost leak. Is the car running smooth throughout the rpms, or are you also seeing some rough/cut-out type running? Ordinarily, with boost leaks at the O'rings, you may also see some rough idle and really crappy performance overall - not to mention the lower boost. Pull the intercooler off and check all the O'rings.

Is there a possibility that the previous owner had installed a lower boost spring than the stock .8 bar (I know that's contrary to the general power junkie mentality of most 930 owners...but stranger things have happened).

I guess there's always the possibility of turbo damage of some sort. Perhaps something got sucked into the turbo and damaged the turbine blades to where it will no longer spin as fast as it should, or maybe the bearings are seriously coked up to where the shaft won't spin freely anymore. Just a thought.

And finally, there is what's called a boost recirculation valve (or some name close to that) which is basically a spring loaded piston. It retracts when under vacuum (such as at idle, or when shifting gears), and thus allows the built up boost to recirculate back to the front of the turbo. It's function is to prevent back-pressure on the turbo during shifts and the resultant drastic slowing of the turbo (i.e., turbo lag and wear-and-tear). If that valve's piston is sticking or not sealing correctlly, then I guess it's possible that some of your boost is being bled off. That's probably the last place I would look, though.

If you don't know yet where all this "stuff" is located on the car, our gracious host Pelican has some pretty good diagrams of most everything. And of course, we all have pictures we could share....did I say Pictures???

Good luck, welcome to the forum.
Old 01-14-2009, 02:20 PM
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