A200 Turbo loses power after 4 min

[alex300ce]

Hi
I have just purchased a A200 Turbo and have a problem where i seem to lose power after approx 4 min of driving.
I dont think its in limp mode, but struggles to get to 100 and generally seems to be around -50% power?
If i turn it off and on it seems to be ok again for another few minutes then does the same.
Ive had it in a garage and they seem to think its a vacuum problem on part of the turbo.(Quoted £1850 for new tubo!)
I think after reading almost every post on the net i can find that it is something more simple, like a MAP sensor maybe?
I have no CEL
Not sure if anyone has ever come across this before?
Any would be great
Thanks

 

[alex300ce]

Having a look around on the net and have seen that there can be problems with the divert air switchover valve? Anyone had problems with these?

 

[alex300ce]

Ok so brought a air divert switch over valve from eBay for £15 inc p&p, 15 min to fit and seems to have cured it!
The turbo now sounds different as in the waste gate has a hiss sound rather than a flutter. I'm just guessing but I'd say the valve was wide open when running good, resulting in over boost which I would say was making it go into limp mode after a few min??
So £15 wasn't to bad after an £1800 quote from the garage!

 

[coupe deville]

£1800 to £15, result, well done