[layback40]

Black smoke = over fueling or bad spray pattern.
Not a HG or head issue. Not a valve timing issue.
#1 injector sensor fault would cause a lack of fuel, so unlikely to be it.
Black smoke can be caused by poor injector spray pattern. You could try some injector cleaner or have the injectors tested. They may need new tips.
I cant see the video you mention.
Is the fuel you are using good quality, fresh & clean? poor fuel can cause issues. In the Autumn around April/May when fuel composition changes I sometimes see a minor black smoke problem with mine. Run tank nearly empty & fill from a different station (more expensive) & problem goes away.