I believe that my '87 900 convertible has never really generated anything beyond basic boost in the year and a half I've owned it. (It hits about 1/4 of the way into the yellow on the gauge.) I recently realized what the boost should feel like after driving a friend's 900, and so I've been trying to figure it out. So far I've verified that the turbo is OK by disconnecting the hose from the solenoid to the wastegate, and I checked the solenoid valve using the Haynes test. The APC box appears OK and is hooked up, though I suppose it might have a problem. But the interesting thing is that when I was poking around in there I discovered that the red capped cruise switch next to the APC box was not hooked up to anything. The hose that should go to it is dangling there with it's T connector. Does this effectively eliminate it from the system, or is it the root of my problem? I tried jumpering the wires that go to it; that made no difference. The hose that I think it would probably come out of just goes straight into that little black cylinder next to the APC box. Out of that same cylinder there is another connector to the left of the other one that seems like it should have a hose connected, but I see no obvious hose that should go to it. My shop manual doesn't really give a good picture of how all these hoses should be connected and I think someone monkeyed with stuff before I owned the car, so any help as to how everything should be hooked up correctly would be appreciated. Thanks in advance,
Emery