I THINK its a hotwire sensor. It heats the screen and measures how much it cools down due to airflow across it (measures the resistance to determine this IIRC). It might not work with the plastic pieces because removing them changes the effective flow area which is something that it's counting on being constant. You can try it, i don't think it would hurt anything unless you run lean under boost (but you knew that). What happened to the plastic?