Gasoline particulate filters (GPFs) are important aftertreatment components that enable gasoline direct injection (GDI) engines to meet European Union (EU) 6 and China 6 particulate number emissions regulations for nonvolatile particles greater than 23 nm in diameter. GPFs are rapidly becoming an integral part of the modern GDI aftertreatment system.
The Active Exhaust Tuning (EXTUN) Valve is a butterfly valve placed in the tailpipe of an exhaust system that can be electronically positioned to control exhaust noise levels (decibels) under various vehicle operating conditions. This device is positioned downstream of the GPF, and variations in the tuning valve position can impact exhaust backpressures, making it difficult to monitor soot/ash accumulation or detect damage/removal of the GPF substrate.
The purpose of this work is to present a unique example of subsystem control and diagnostic architecture for an exhaust system combining GPF and EXTUN. In particular, the On-Board Diagnostics (OBD) controls are required to detect a disconnected/plugged downstream hose when combining a differential pressure (dP) sensor and an electronically controlled EXTUN valve in an exhaust system containing a GPF. The regulatory implications related to failing to detect a disconnected/plugged downstream hose are also discussed. Validation data from the control strategy under different operating conditions is reviewed.
