Method for operating an engine

An engine operating method, comprising:

• determining ceasing regeneration of a particulate filter;
• increasing boost pressure in an engine air intake via a controller while driver demand torque is substantially constant in response to ceasing regeneration of the particulate filter to increase a selective catalytic reduction catalyst (SCR) efficiency via cooling a temperature of the SCR below a first threshold temperature;
• and
• adjusting an EGR valve position based on the driver demand torque and engine speed in response to ceasing the regeneration of the particulate filter and before SCR temperature is less than the first threshold temperature.

An engine system, comprising:

• a two stroke opposed piston diesel engine including at least one cylinder;
• an exhaust system coupled to the two stroke engine including an oxidation catalyst, a selective catalytic reduction catalyst (SCR), and a particulate filter;
• and
• a controller including executable instructions stored in non-transitory memory to increase exhaust flow to the SCR via increasing boost pressure while driver demand torque is substantially constant in response to ceasing to regenerate the particulate filter and a SCR temperature being greater than a first threshold temperature,
• where the first threshold temperature is a temperature above which SCR efficiency is less than a threshold.