2002 Ford Focus • 100,000 miles

Hi there I have a 2002 1.8 tdci focus and I live in Tenerife, when I go up to drive at altitude approx 7000ft above sea level the car drives fine. I turn off the engine and it starts again perfectly but the turbo stops working. When I get back down to about 3000ft I switch off the engine and restart and the Turbo works again and I have full power as normal. Something to do with thinner air I suppose but other cars with turbo's seem to be fine. Can someone advise please. There are no warning lights that come on?
October 4, 2011.

There are baro sensors that work on atomsphereic pressure. You need someone to monitor the sensor to determine if the sensor is working correctly.