A metal wire grid protects the MAF sensor element and also avoids particles ending up in the intake and ultimately ending up in the engine. This grid or strainer sometimes gets damaged. A damaged grid my break up dropping loose metal wire bits in the intake. This is obviously a bad thing and the grid needs replacing. I offer new grids at an affordable price. Your MAF has two of them, held in place by a metal ring. Contact me if the ring is missing.