Thanks for your help guys I know it looks like a book but I’m trying to be as detailed as possible. I’m having some trouble out of my 2006 XC-90 2.5 Turbo AWD. First the turbo has started whining (or whistling) it’s louder in the morning when it’s cold and the sound lowers when it gets warm. But under acceleration you can still hear it whining. I have checked the 2 exhaust gaskets that connect the turbo to the manifold and the exhaust pipe and there is no leaks. I did see that the exhaust manifold was leaking from the head because the nuts were backing out. I tightened those back up but it still had the same problem. I did check the inter-cooler hose that goes across top of the motor and the rubber piece that connects the hard plastic to the turbo is real soft and easy to compress. The molded rubber hose that connects it to inter cooler is the same soft and easy to compress. I don’t know if that could be an issue and I have also noticed oil inside of the inter-cooler hose and the molded hose there’s not lots of oil but you can tell over 118,000 miles that it has collected. I haven’t checked the intake hose for the turbo yet but on top it looks very good and from under the engine it looks like it connects well to the turbo. I can’t see any more of the hose because of the transmission and the geared box that goes to the rear. What are your thoughts about fixing the whining (or whistling) or do you guys have the same problem with yours? The engine is also stumbling but I do have a mass airflow sensor code, o2 bank sensor code, and fuel bank sensor code. The mass airflow sensor code came on a month after the turbo started whining (or whistling). Then after some time the others came on. My question is if I just replace the mass air sensor will the o2 sensor code and fuel bank code go away because the engine is mixing the right air to fuel ratio, or do you think that the others have now gone bad? What do you call the molded hose that goes from the head (were the coil packs are) to a box under the intake? That hose did crack because is was brittle but I rigged it so that it wouldn’t lose vacuum. The only problem is I had to step it down in size so that the final rubber hose would fit inside the molded hose the goes into the head. I started with a ¾ heater hose and ended with a ¼ fuel hose. Thanks for all of your help I really appreciate it.

 

Unfortunately I couldn't find a cheap fix to the whining problem, but a new turbo will certainly fix the problem. In the picture you can see metal flakes on the blades and shaft nut. You can also see all the oil everywhere it’s also in the inter-cooling hose and the turbo air intake hose. With the new turbo and M.A.S. everything should be running great at least it better be.