Black smoke usually means "running rich." Has your fuel economy worsened? In my case it had nothing to do with the turbo - it was a bad ECT (engine coolant temp sensor).

I did have what I thought was smoke from the exhaust last year, every time I boosted the car ('91 745 Turbo) there was a plume of smoke behind me (whitish gray). Turned out it was not anything internal but a bad cam cover gasket that spewed oil onto the exhaust manifold/downpipe everytime there was any pressure. Always try the simplest thing first in troubleshooting (i.e. "Is the computer plugged in?").
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Darius in Albany NY '86 744 GLE (175K, given to my mother-in-law); '91 745 Turbo (174K-my 'Little Red Wagon'), '00 Toyota Camry (65K - my wife's transportation appliance)

Black smoke?

Split hose somewhere after the AMM.

Remove and visually check the hoses between the AMM-turbo inlet and turbo outlet-intercooler.

Replace the turbo outlet-intercooler hose (long thing)

Drill a 1/4 hole into the plastic top from a rrattle can of spray paint.

Squeeze the top into the inlet of the turbo-intercooler hose and clamp it.

Apply not more than 15psi ship air via blow nozzle 9have helper do this)

Go listen and feel for escaping air from intercooler, intercooler outlet hose (short), intkake tube, double curced hose from tube to throttle body, FI hoses from tube into/out of Idle Control Valve (that's where I found my 4" split!).

Also check bad vacuum hoses, throttle body and intake manifold gaskets.

If you are SURE you don't have any leaks, swap in known good AMM and/or fuel pressure regulator.
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'Can't understand why people abort Volvos, either' '89 740 Turbo, 122,000 miles