A friend in France has a VW Transporter 2.5 Turbo Diesel van and has had it from new - Approximately 5 years and 50k miles. It runs on regular pump diesel, but has suffered from intermittent boost failure under load for over a year; the reason turned out to be a broken sensor and a gummed up / sutted up variable vane in the turbo. The turbo was cleaned with a kit from ebay that smelled like oven cleaner (apparently), but seemed to clean the turbo after an hour and it runs properly now.
Is this something that affects all modern turbo diesels or was it just that van?