I was driving tonight and all of a sudden i heard a noise. It sounded like i caught a can. It wa something vibrating. I noticed no lose of horsepower. I park pop my hood and have a friend rev it. On the pass side of the motor, i saw a blue spark. I shine a flashlight down there and its this sensor of some sort. The sensor is surrounded by a sheet of metal. I got underneath and grabbed this sheet of metal. It is definately the thing vibrating. Any clue what it is? Whats the purpose of the sheet of metal? Is the sensor and o2 sensor?