yeah i have a 89 760 turbo with 114000 miles on it that i just bought it runs but very under powered it did some checking and found that the turbo wastegate rod was disconnected , so when i reconnected and drove the engine would not rev over 2500 it missed and black smoke was coming out of the exhaust, it also sounds like you can here the boost coming out somewhere, i replaced the vacuum lines, the hose from the mass air flow sensor to the turbo, removed the catalytic converter, all to no avail, any help would be appreciated

 

Make sure the rest of the hoses are good.

Something is making it run way to Rich.
Black smoke means running rich.
Plugs
Wires
Injectors
Mass flow sensor
O2 sensor

They could all make it run like that.

 

ive checked all the hoses and theres no code or ses lamps on the only time i have this problem is when the turbo wastegate rod is hooked up, other than that it runs as good as a four cylinder in a car that big will run, the wires plugs and o2 sensor are new also

 

Maybe wrong computer in the car.