Systems and methods for preventing thermal spikes at exhaust gas catalysts

A method of preventing thermal spikes at a three-way catalyst (TWC) in an exhaust system of an engine of a vehicle, the method comprising:

• receiving, by a controller and from each of one of more oxygen (O2) sensors disposed proximate to the TWC in the exhaust system, a measured oxygen level of exhaust gas produced by the engine;
• detecting, by the controller, whether one of a fuel enrichment event and a fuel cutoff event has been initiated, wherein the fuel enrichment event comprises operating the engine with a rich fuel/air ratio and the fuel cutoff event comprises operating the engine with a lean fuel/air ratio;
• and
• in response to detecting that one of the fuel enrichment and the fuel cutoff event has been initiated:
• temporarily disabling, by the controller, the other of the fuel enrichment event and the fuel cutoff event from occurring to prevent an exhaust gas temperature thermal spike that could damage the TWC,
• while the other of the fuel enrichment event and the fuel cutoff event is disabled, performing, by the controller, stoichiometric closed-loop fuel control using the one or more O2 sensors to drive the exhaust gas fuel/air ratio to stoichiometry and an oxygen storage capacity of the TWC to a balanced state, and
• when measurements from the one or more O2 sensors indicate at least one lean-to-rich transition and one rich-to-lean transition in the exhaust gas oxygen level has occurred, re-enabling, by the controller, the other of the fuel enrichment event and the fuel cutoff event.