900 Turbo: Loss of power with no other symptoms

[cdawzrd]

I have a '97 900 SE Turbo that has been running fine after some initial problems (needed a DIC, stuck wastegate, new BPC valve, etc) that got fixed over the last year or so.

Now, I have a new problem: It feels like I've lost about half of my horsepower all of the sudden! 0-60 time is about double, and I can floor it in first or second and just...wait for the revs to go up.

Boost gauge is in the middle of the yellow rather than building full boost. I tried bypassing the BPC to try to rule out the wastegate and BPC, but unlike the last time (which was a wastegate problem), this had no effect rather than the overboost I expected.

No trouble codes, no odd smoke, no stuttering or any other symptoms that I can see. Just no power.

Now unfortunately I currently don't have a real jack or a good flat working surface to lift the car, so the things I can do at home are limited to the top of the engine compartment... One thing that came to mind was a restricted exhaust, but I don't think I can easily check that.

Can you guys think of anything else that might cause this problem that I could check out inside the engine compartment, before I take it to a shop to look at the exhaust / cat?

[OddyseusDSM]

BPC is the issue, its not blocking the signal to the wastegate which means you're running on spring pressure alone, ~5-6 psi

[deeps]

have you checked to see if the retaining clip that holds the actuating arm to to the wastegate has fallen/broken off?

[OddyseusDSM]

there would be no boost as the wastegate would just blow open, wouldnt even get outta the white

[cdawzrd]

Originally Posted by OddyseusDSM

BPC is the issue, its not blocking the signal to the wastegate which means you're running on spring pressure alone, ~5-6 psi

No, this isn't the problem. Earlier when I was diagnosing the BPC, I ran the compressor straight to the wastegate actuator, and I know what that feels like. This is way more sluggish than base boost...it feels like I'm hauling a huge trailer!

Also, yes, I've checked the turbo components. The wastegate actuator is working and connected, and the BPC works fine when I pull it out and test on my workbench.