NOx control during engine idle-stop operations

An engine system, comprising:

• an engine that is selectively deactivatable responsive to idle-stop conditions;
• an emission control device coupled to an engine exhaust manifold, the device including a first, upstream SCR catalyst in face-sharing contact with a second, downstream catalyst;
• a third close-coupled three-way exhaust catalyst positioned upstream of the emission control device;
• and
• a control system with non-transitory computer readable instructions for,
• during an engine restart from idle-stop, adjusting fuel injection to be richer than stoichiometry to regenerate the third catalyst, a degree of richness adjusted based on an ammonia content of the first catalyst.