These sensors are designed to determine the amount of air being taken into the engine and adjust the fuel mixture accordingly to optimize power and efficiency. If the sensor goes bad it can cause all sorts of problems from check engine lights to knocking and pinging. Most airflow sensors are designed to work within certain parameters but if you have modified your engine the increased airflow can exceed the limits of the sensor and cause running issues. In addition, the factory mass airflow sensors can also be restrictive to airflow and hinder power in certain high-performance applications.