I like the injection idea. You could also make a mixture to periodically brush on the pork while cooking. It will probably add some time to the cook, but might be worth it for extra flavor.Last time, I blended some pineapple with the homemade adobo for the overnight marinade, and the pork was basically pickled by the time it came off the grill—so I skipped that this time and it was an improvement. Maybe Al Pastor is just supposed to be soft. I like the injection idea of you do it right before you put it on.