on the CR the advance "translate" the injection before that if you have 850us time opening the injector and the advance to 20? before tdc anticipating duck, always 850us but starting at 22? then you're going to inettare before....
in the vag pd instead if you have the advance that, say, begins to inject at 19? before tdc..with the injector, which remains open for 28? in total you have 19? btdc and 9? after the pms you have 28? total...
if by 21? of advance the total duration will be? 30?.. because the injector will open 21? before tdc but close? always 9? degrees after tdc...