i have a few sets of tbi injectors i harvested probably 15 years ago that still have the paint on them. this was back when no one wanted this stuff and lower milage units were not hard to come by in the wrecking yard. the worst thing you can do is take a screwdriver and scrape trying to find the part number. i use a tooth brush and carb cleaner usually id checking them insitu. Best way is to get the injectors flow tested and they get cleaned at the same time.