METHOD TO MONITOR PRESSURE DROP ACROSS A SELECTIVE CATALYST REDUCER FOR ENGINE AND EXHAUST AIRFLOW DIAGNOSTICS

摘要

A method to diagnose exhaust system malfunction in an electronically controlled internal combustion engine having an exhaust system and including a Selective Catalyst Reducer (SCR) is disclosed. The method may comprise determining ambient barometric pressure; determining a baseline curve of exhaust flow; and monitoring said exhaust flow rate for changes in exhaust flow rate compared to change of exhaust pressure across the SCR to diagnose exhaust system malfunction.