940 94 940T is blowing black smoke under boost

My car has been blowing crazy amounts of black smoke under boost. It will only hold 15 psi at full throttle even with the wastegate disconnected. It does shoot up to 20, but then falls down to 15. It feels like it has a rev limiter as it will not rev to 6000. It sputters (hesitates) and starts smoking.

I have done a full tune up, and it still does it. I have tried a different AMM, FPR, Coil, ecu temp sensor, plugs, cap, rotor, wires, and compression testing. My turbo is really really loud. It sounds like all the air is blowing out somewhere where it shouldn't be, but I can't find any leaks after looking many times. I do have a whole lot of shaft play in the turbo, and it does appear that it could be hitting the housing.

My question is, wouldn't a blown turbo blow white smoke because it is burning oil? My o2 sensor is right behind my exhaust housing, so could that oil be messing up my o2 sensor? My air fuel gauge is reading rich when it is blowing out the smoke and hesitating, so that leads me to believe that it should be telling the ecu to lean it out. Has anyone else had an issue like this?

Rebuild or put in another turbo. You know it's dead, so replace it and report back in. Ya should do it ASAP before the turbo damages something else.

Sounds more like an air leak which is what you suggested. Maybe a cracked intercooler? Although I have never heard of this happening.

Black smoke suggests a mixture problem(rich) which could be caused by a leak between the compressor side of the turbo and the intake manifold.

The hissing sound could very well be an air leak. You know the turbo is done so replace it first. If that fixes things, then your issues are solved. If not, cap off the turbo side of the intercooler and pressure test the intake system.

Black smoke is a super rich condition. White "smoke" is brake fluid or water getting into the combustion chamber. Blue/gray smoke(burning engine oil)is what a turbo will emit when the seals are failing.

Thanks all for the input. I will be replacing the turbo. I just hope that fixes this problem as I really need this car to work. Anyone know for sure if you can just swap out the conical for the flat flanged exhaust housing on a 15G? I am pretty sure you can, but I'm not sure if they are all the TD04HL15G like the one I have on there. I think the donor car is a 95 850 turbo this time around.

Conical is what you have on there now. If you switch to a FF exhaust housing you need to swap in a FF downpipe. Just get a conical hot side and you'd be plug & play. Also, if the turbo hasn't yet been re-clocked for RWD, you'll need to do that plus make yourself a wastegate actuator bracket.

No I have a flat flange. I don't want to make a new downpipe. It is a little rusty but custom 3". And I already have a bracket on the existing 15g. Sounds like I can just switch hot sides. Thanks.

Found the problem!! It was a popped silicone coupler on my intercooler piping. That was my first thought as to what it was, but it was a challenge to find. I had one cheapy that got rock hard and split on the bottom. The rest are in good shape. The oil on my battery was the giveaway. At least my stage 0 is refreshed! Thanks for the help.