Why is there black smoke from exhaust when you put your foot down on peugeot 405 turbo?

this sounds alot like a turbo failure, although there could well be a leak in the pipes leading from the turbo to the intercooler, or from the intercooler to the inlet manifold.

also check the intercooler for leaks.

or it is the vacuum pipe that operates the waste gate on the turbo, or a seized waste gate.