1994 850 Turbo

I don't have any experience with Volvo turbo's... Only VW turbo's - but loss of power and potential stalling can be caused by a failed MAF sensor (O2 sensors also cause similar symptoms) on these cars - and I think both cars use a Bosch (Motronic) engine computer, so failure of these devices

***MAY*** be similar (but we're dealing with a 10 year old Volvo and a new VW here as my two references, so there are bound to be differences aplenty in management technology)... No expert on a blown turbo, but I think it's more of a slow death where you would see oil in your exhaust, notice the power isn't as strong anymore... Now I could very much be wrong, but unless the turbo seized because of the bearings, or it threw a blade on the "fan"/"impeller" (whatever the thing that makes the pressure is called) I can't see one dieing instantly.

Again not an expert, but check the MAF and O2 sensors first.

My experience of a dying turbo was a sudden 'kangarooing' at high acceleration (this in a 1990 Nissan engine). The wastegate was sticking closed, causing overboost. The ECU saw the overboost and cut the fuel. It wasn't a slow loss of power or gradual event. It got more frequent as the wastegate got worse. If your wastegate sticks open, you will get no boost at all!

I'd imagine that the ECU logs would show what was actually happening if it was the ECU cutting the power. If it isn't the ECU, then it shouldn't be hard to fit a boost gauge to find out what boost is being provided.

In the UK it is much cheaper to get turbos reconditioned by someone like Turbo Technics. I think about £250 as opposed to £1000 for a new unit.

I had a turbo let go on a Mitsubishi back in 1985 and it was most definitely a sudden death event where it developed an unhealthy thirst for oil and a sudden ability to drop smokescreens that James Bond would have envied. After only a mile of running (to get it home) it leaked black il from the exhaust tailpipe. Don't drive a cat equipped turbo car if this happens as you will kill the cat! Took ages for the oil to stop burning in the pipe after it was fixed too.....

I believe that is the normal failure mode for a turbo....

Wastegates jammimg can cause the car to do as Tim said. Thats easy to check as all you need to do is remove the heat shield on top of the turbo, disconnect the rod from the wastegate diaphragm and wiggle the arm it was attached to... if it feeels tight there is your problem. It should flap loosely. The good news is it is a lot cheaper and easier to fix than a full turbo rebuild! To check the wastegate should take not much longer than half an hour for someone who knows how to use a 12mm spanner...

I wish I'd known that in 1996...

:-)