Boogyman, as previously mentioned by others, the three most likely causes would be a boost leak, a faulty wastegate and a partially blocked exhaust. A boost leak IMO is the most likely and probably cause with the faulty wastegate a close second. Even if a boost leak isn’t the cause of this...
I'm sorry, I still don't see the problem here.
This whole discussion about whether or not engines have very little overlap vs. some overlap is absolutely moot because as far as the OP is concerned, it should be extremely easy to find a crank position where both intake and exhaust valves are not...
yes engine off.
Pat, it's true you may get air leaking into a cylinder (you should remove the oil cap or somthing to make sure pressure dosen't build in the crankcase). I'm not sure I see the problem with this, maybe you can elaborate? usually it's quite easy to find all the leaks this way.
The best way to check for boost leaks is to make some sort of air fitting adapter that you can use to couple the inlet of your turbo to an air compressor. Then pressurize the entire system with at least as much boost as you plan to run and listen for leaks.
Ralf
I've never used it, but it's supposed to work by breaking the surface tension of the water. I've heard of people added a drop or two of dish washing soap to do the same thing. Not sure how successful this would be though.