Powerless at higher speeds

[VMS]

Hy there. I was wondering if you could help me please. I have a strange issue on my smart. Is a 2004 0.7 petrol smart. The simptoms are the lack of power at over 50 miles/h. So when i start in first gear, second... It goes fine and i hear the turbo working too. When i reach higher speeds and i accelerate i feel that i lose 50% of the power and the speed start to go down or very very hard up. It does not feel like a turbo car anymore. Please help me fix this problem!
P. S. My radio also is not working. At service they changed the windscreen wipers engine and after that radio does not start anymore.

[VMS]

[Thrumbleux]

First thing to check is the E-clip that holds the actuator rod to the turbo wastegate arm. They corrode and fall off leaving the wastegate open and no boost.
FQ101 and Evilution sites have details,

[VMS]

But i have boost in 1 2 3 and 4 gear... Also in 5 and 6 but when i press more the acceleration it pops and it feel like an INSTANT lose of power. If i restart the engine the car goes fine again...

[Thrumbleux]

I would check electrical connections ie all earth leads.
Why the need to restart the engine? EML showing? ''when i press more the acceleration it pops'' What do you mean? A popping noise? If so, from where (exhaust, engine bay, etc)?

[VMS]

No light in the dashboard showing. The car INSTANT lose 50% of the power when for example i climb a hill with 4 gear and i press the pedal to 70% so it can climb it makes this problem...it loses the turbo. After that i stop the car and i restart the engine and the turbo is back on.

[Ocracoke]

Possible crack in the turbo manifold? Sounds vaguely similar to my experience of the manifold going on a trip back from York. Happily plugging along before a sudden loss of power. Came off the road, let the car cool down a little with the engine off before resuming for home.

[VMS]

At my car is no need to cool down. Just reatar engine and works. I think is an elecrical problem...

[mikerj]

Sounds very much like it's over-boosting and the ECU is keeping the wastegate open to protect the engine. This is a common fault and most always caused by a faulty boost control solenoid (aka "cycle valve"). The valve is located on the turbo intake pipe (TIK pipe) and is real pain in the neck to change, but the good news is they aren't very expensive (<£20).

[VMS]

You are shure that this is the problem mate?

[Thrumbleux]

If it goes overboost due to cycle valve it goes into limp mode - EML and reboot of ECU has to be done via battery disconnect or fuse pull. A failed cycle valve will trip the ECU into limp mode in the lower gears also. If it overboosts - you'd notice. It pulls like a train before incurring limp mode.

What happens if you just keep on driving (without stop/restart) and end up in the low gears again?