Restricted filter diagnostic system and method

摘要

A restriction diagnostic system for a vehicle comprises a pressure difference module and a diagnostic module. The pressure difference module determines a pressure difference between an ambient air pressure and a filtered air pressure measured at a location between an air filter and a valve that is selectively opened to enable ambient airflow through the air filter to a fuel vapor canister. The diagnostic module selectively diagnoses restriction of the airflow through the air filter when the pressure difference is greater than a predetermined pressure.