Did you have oil in the turbo to cooler pipe?

if a turbo has been leaking oil gets everyware and can sit in the bottom of a 500 cooler untill u pull up where u have a vacuum and more oil is then passed to the inlet undo ur plenum and check here for oil....
same goes when u boot it as forced air carries oil once again

U will find it only takes a drip to produce a lot of smoke!!!!!!

B carefull mate cos oil burning can and will cause DET!!!!!!!! more so on no 4 piston as is the last to be fed....