Idle adjustment in this engine is mechanical (base idle) and electronic (ELR actuator). There's no vacuum or pressure control of idle. There is no pneumatic line to the idle trim selector, only wires. Per the diagram, the branch close to the ALDA goes to the 50*C switchover valve (Y29). Below 50*C coolant temperature (single pole sensor by the thermostat), the boost signal is blocked from the transmission vacuum transducer (123) also called blue flying saucer (BFS). If the engine was cold when you blew, it should have been blocked. When the engine is warm, you should be able to blow through to the BFS. I don't know if you can blow through the BFS or if it blocks further blowing. This line has nothing to do with idle or engine performance, short of a wholesale leak that subverts the signal to the ALDA. You might add another branch just upstream of the ALDA to plumb a boost gauge to the cabin. You should see about 5 psi at 2200 rpm under load and a max of 12-13 psi.

Removing the ALDA should allow as much fuel as the IP can provide under max boost even when boost isn't available hence smoke. If performance is insufficient with the ALDA removed:

- there's a problem with fuel supply or inside the IP
- the turbo is tired or there's a serious leak in the manifold
- you need to turn up the full load setting; probably should install an EGT gauge first
- put this engine in the SDL - http://cgi.ebay.com/ebaymotors/261281967606

Sixto
87 300D