Minor injector knock due to carbon build up will vanish with the diesel
purge treatment. If it comes back right away, likely it's more than
just carbon -- worn injector, carbon in the prechamber, low
compression, late timing, etc.
If it only happens cold and under hard acceleration before completely
warmed up, and Italian Tuneup may cure it -- these engines collect
carbon in the prechambers if not driven hard enough.
If it's only one cylinder and you can located by loosening the
injection lines one at a time, then you should have that injector
checked.
Peter
