Cylinder deactivation to reduce fuel enrichment after fuel cutoff modes
A system includes a fuel cutoff module and a cylinder deactivation module. The fuel cutoff module generates a fuel cutoff signal when a deceleration fuel cutoff condition occurs, wherein fueling to M cylinders of an engine is disabled based on the fuel cutoff signal, and wherein M is an integer greater than or equal to one. The cylinder deactivation module deactivates the M cylinders in response to the fuel cutoff signal.
1. A system comprising:
a fuel cutoff module that generates a fuel cutoff signal when a deceleration fuel cutoff condition occurs,
wherein the deceleration fuel cutoff condition occurs when a speed of a vehicle is greater than a speed threshold and an accelerator position is less than a position threshold;
wherein fueling to M cylinders of an engine is disabled based on the fuel cutoff signal;
wherein M is an integer greater than or equal to one;
an oxygen storage module that determines an amount of oxygen stored in a catalyst; and
a cylinder deactivation module that, after fueling to the M cylinders is disabled, deactivates the M cylinders in response to a determination that the amount of oxygen stored in the catalyst is greater than a predetermined oxygen amount.
2. The system of claim 1 , wherein the cylinder deactivation module deactivates an intake valve and an exhaust valve of the M cylinders to prevent airflow from the M cylinders to the catalyst.
3. The system of claim 1 , wherein the predetermined oxygen amount indicates nitrogen oxides (NOx) in exhaust gas downstream from the catalyst.
4. The system of claim 1 , wherein the oxygen storage module determines the amount of oxygen based on a signal that indicates an amount of oxygen in exhaust gas downstream from the catalyst.
5. The system of claim 1 , wherein the deceleration fuel cutoff condition occurs when the engine outputs negative engine torque.
6. The system of claim 1 , wherein the cylinder deactivation module deactivates the M cylinders to prevent an increase in the amount of oxygen stored by the catalyst.
7. A method comprising:
generating a fuel cutoff signal when a deceleration fuel cutoff condition occurs,
wherein the deceleration fuel cutoff condition occurs when a speed of a vehicle is greater than a speed threshold and an accelerator position is less than a position threshold;
disabling fueling to M cylinders of an engine based on the fuel cutoff signal;
wherein M is an integer greater than or equal to one; and
determining an amount of oxygen stored in a catalyst; and,
after fueling to the M cylinders is disabled, deactivating the M cylinders in response to the fuel cutoff signal in response to a determination that the amount of oxygen stored in the catalyst is greater than a predetermined oxygen amount.
8. The method of claim 7 , further comprising:
deactivating an intake valve and an exhaust valve of the M cylinders to prevent airflow from the M cylinders to the catalyst.
9. The method of claim 7 , wherein the predetermined oxygen amount indicates nitrogen oxides (NOx) in exhaust gas downstream from the catalyst.
10. The method of claim 7 , further comprising:
determining the amount of oxygen based on a signal that indicates an amount of oxygen in exhaust gas downstream from the catalyst.
11. The method of claim 7 , wherein the deceleration fuel cutoff condition occurs when the engine outputs negative engine torque.
12. The method of claim 7 , further comprising:
deactivating the M cylinders to prevent an increase in the amount of oxygen stored by the catalyst.
13. The method of claim 7 wherein M is equal to a total number of cylinders of the engine.
14. The system of claim 1 wherein M is equal to a total number of cylinders of the engine.