Methods and systems are provided for an emission control device that includes a particulate filter with a bypass. In one example, a method includes bypassing the particulate filter when the exhaust gas has a decreased soot load and when the particulate filter has a decreased soot storage. The method further includes reducing the filter bypass flow and terminating or adjusting a deceleration fuel shut-off operation due to an exhaust temperature proximate to the particulate filter being above a threshold.

Methods and systems are provided for an emission control device that includes a particulate filter with a bypass. In one example, a method includes bypassing the particulate filter when the exhaust gas has a decreased soot load and when the particulate filter has a decreased soot storage. The method further includes reducing the filter bypass flow and terminating or adjusting a deceleration fuel shut-off operation due to an exhaust temperature proximate to the particulate filter being above a threshold.

An exhaust treatment system includes an engine, an exhaust line in fluid communication with the engine, a three-way catalyst downstream of the engine on the exhaust line, a particulate filter downstream of and proximate to the three-way catalyst on the exhaust line, and a sorbent unit comprising a first sorbent and a second sorbent downstream of the three-way catalyst and the particulate filter on the exhaust line. The first sorbent and the second sorbent are proximate to a tailpipe of the exhaust line. A method of treating an exhaust emission from an internal combustion engine during an engine cold-start is also described.

An exhaust treatment system includes an engine, an exhaust line in fluid communication with the engine, a three-way catalyst downstream of the engine on the exhaust line, a particulate filter downstream of and proximate to the three-way catalyst on the exhaust line, and a sorbent unit comprising a first sorbent and a second sorbent downstream of the three-way catalyst and the particulate filter on the exhaust line. The first sorbent and the second sorbent are proximate to a tailpipe of the exhaust line. A method of treating an exhaust emission from an internal combustion engine during an engine cold-start is also described.

Methods and systems are provided for diagnostics of a gasoline particulate filter in an exhaust system. In one example, a method may include indicating degradation of a hose coupled across a particulate filter responsive to a difference between a first differential pressure and a second differential pressure being greater than a threshold, the first differential pressure measured by a differential pressure sensor positioned in the hose responsive to a downstream exhaust tuning valve being fully open, the second differential pressure measured by the differential pressure sensor responsive to the exhaust tuning valve being fully closed.

Methods and systems are provided for diagnostics of a gasoline particulate filter in an exhaust system. In one example, a method may include indicating degradation of a hose coupled across a particulate filter responsive to a difference between a first differential pressure and a second differential pressure being greater than a threshold, the first differential pressure measured by a differential pressure sensor positioned in the hose responsive to a downstream exhaust tuning valve being fully open, the second differential pressure measured by the differential pressure sensor responsive to the exhaust tuning valve being fully closed.

An exhaust gas control system for an internal combustion engine, before execution of a filter regeneration process, executes a pre-regeneration process that is a process of raising a temperature of a filter to a second target temperature lower than a first target temperature and increasing the concentration of NO2 contained in exhaust gas flowing into the filter for a predetermined period. The first target temperature during execution of the filter regeneration process in the case where a speed of change in a detected value of a differential pressure sensor during execution of the pre-regeneration process is high is set so as to be lower than the first target temperature in the case where the speed of change is low.

An exhaust gas control system for an internal combustion engine, before execution of a filter regeneration process, executes a pre-regeneration process that is a process of raising a temperature of a filter to a second target temperature lower than a first target temperature and increasing the concentration of NO.sub.2 contained in exhaust gas flowing into the filter for a predetermined period. An execution time of the filter regeneration process when a physical quantity that correlates with a speed of change in a detected value of a differential pressure sensor during execution of the pre-regeneration process is large is shorter than an execution time of the filter regeneration process when the physical quantity is small.

A method for controlling a valve for directing an exhaust gas stream through an exhaust duct having an after treatment device and a bypass duct in an exhaust system of a vehicle is provided. The method includes receiving first sensor signals from a first sensor coupled downstream from the exhaust after treatment device, and processing the first sensor signals to determine a first temperature of an outlet exhaust gas stream. The method includes determining a bypass command based on whether the first temperature exceeds a first pre-defined threshold for the outlet exhaust gas stream. The method also includes outputting a control signal based on the determining of the bypass command to a valve coupled to the bypass duct and the exhaust pipe upstream of the after treatment device to move the valve between a first state and a second state.

A method for controlling a valve for directing an exhaust gas stream through an exhaust duct having an after treatment device and a bypass duct in an exhaust system of a vehicle is provided. The method includes receiving first sensor signals from a first sensor coupled downstream from the exhaust after treatment device, and processing the first sensor signals to determine a first temperature of an outlet exhaust gas stream. The method includes determining a bypass command based on whether the first temperature exceeds a first pre-defined threshold for the outlet exhaust gas stream. The method also includes outputting a control signal based on the determining of the bypass command to a valve coupled to the bypass duct and the exhaust pipe upstream of the after treatment device to move the valve between a first state and a second state.