Volumetric efficiency determination systems and methods

1. A cylinder control system of a vehicle, comprising: a cylinder control module that determines a desired cylinder activation/deactivation sequence and that activates and deactivates valves of cylinders of an engine based on the desired cylinder activation/deactivation sequence; and a volumetric efficiency (VE) module that determines a volumetric efficiency based on a cylinder activation/deactivation sequence of the previous Q cylinders in the firing order, wherein Q is an integer greater than one.

2. The cylinder control system of claim 1 wherein the VE module determines the VE further based on a predicted intake port pressure at an intake valve closing timing and a predicted exhaust port pressure at an exhaust valve closing timing.

3. The cylinder control system of claim 2 wherein the VE module determines the VE based on the predicted intake port pressure divided by the predicted exhaust port pressure.

4. The cylinder control system of claim 2 wherein the VE module determines the predicted intake port pressure based on a pressure within an intake manifold of the engine measured before the intake valve closing timing.

5. The cylinder control system of claim 2 wherein the VE module determines the predicted exhaust port pressure based on a mass of air trapped within a cylinder and an engine speed determined before the exhaust valve closing timing.

6. The cylinder control system of claim 2 wherein the VE module determines the VE further based on an engine speed.

7. The cylinder control system of claim 6 wherein the VE module determines the VE further based on an intake valve phasing parameter and an exhaust valve phasing parameter.

8. The cylinder control system of claim 7 wherein the VE module determines the VE using one of a function and a mapping that relates the cylinder activation/deactivation sequence of the previous Q cylinders, the predicted intake port pressure, the predicted exhaust port pressure, the engine speed, the intake valve phasing parameter, and the exhaust valve phasing parameter to the VE.

9. The cylinder control system of claim 7 wherein the VE module:

determines a base VE value based on the engine speed, the predicted intake port pressure, and the predicted exhaust port pressure;

determines a multiplier value based on the intake valve phasing parameter, the exhaust valve phasing parameter, and the cylinder activation/deactivation sequence of the previous Q cylinders;

determines an offset value based on the intake valve phasing parameter, the exhaust valve phasing parameter, and the cylinder activation/deactivation sequence of the previous Q cylinders; and

sets the VE equal to the offset value plus a product of the base VE value and the multiplier value.

10. The cylinder control system of claim 9 wherein the VE module:

determines the base VE value using a mapping that relates the engine speed and a value equal to the predicted intake port pressure divided by the predicted exhaust port pressure to the base VE value;

determines the multiplier using one of a first polynomial equation and a first bi-cubic spline that relates the intake valve phasing parameter, the exhaust valve phasing parameter, and the cylinder activation/deactivation sequence of the previous Q cylinders to the multiplier value; and

determines the offset value using one of a second polynomial equation and a second bi-cubic spline that relates the intake valve phasing parameter, the exhaust valve phasing parameter, and the cylinder activation/deactivation sequence of the previous Q cylinders to the offset value.

11. A cylinder control method comprising: determining a desired cylinder activation/deactivation sequence; activating and deactivating valves of cylinders of an engine based on the desired cylinder activation/deactivation sequence; and determining a volumetric efficiency (VE) based on a cylinder activation/deactivation sequence of the previous Q cylinders in the firing order, wherein Q is an integer greater than one.

12. The cylinder control method of claim 11 further comprising determining the VE further based on a predicted intake port pressure at an intake valve closing timing and a predicted exhaust port pressure at an exhaust valve closing timing.

13. The cylinder control method of claim 12 further comprising determining the VE based on the predicted intake port pressure divided by the predicted exhaust port pressure.

14. The cylinder control method of claim 12 further comprising determining the predicted intake port pressure based on a pressure within an intake manifold of the engine measured before the intake valve closing timing.

15. The cylinder control method of claim 12 further comprising determining the predicted exhaust port pressure based on a mass of air trapped within a cylinder and an engine speed determined before the exhaust valve closing timing.

16. The cylinder control method of claim 12 further comprising determining the VE further based on an engine speed.

17. The cylinder control method of claim 16 further comprising determining the VE further based on an intake valve phasing parameter and an exhaust valve phasing parameter.

18. The cylinder control method of claim 17 further comprising determining the VE using one of a function and a mapping that relates the cylinder activation/deactivation sequence of the previous Q cylinders, the predicted intake port pressure, the predicted exhaust port pressure, the engine speed, the intake valve phasing parameter, and the exhaust valve phasing parameter to the VE.

19. The cylinder control method of claim 17 further comprising:

determining a base VE value based on the engine speed, the predicted intake port pressure, and the predicted exhaust port pressure;

determining a multiplier value based on the intake valve phasing parameter, the exhaust valve phasing parameter, and the cylinder activation/deactivation sequence of the previous Q cylinders;

determining an offset value based on the intake valve phasing parameter, the exhaust valve phasing parameter, and the cylinder activation/deactivation sequence of the previous Q cylinders; and

setting the VE equal to the offset value plus a product of the base VE value and the multiplier value.

20. The cylinder control method of claim 19 further comprising:

determining the base VE value using a mapping that relates the engine speed and a value equal to the predicted intake port pressure divided by the predicted exhaust port pressure to the base VE value;

determining the multiplier using one of a first polynomial equation and a first bi-cubic spline that relates the intake valve phasing parameter, the exhaust valve phasing parameter, and the cylinder activation/deactivation sequence of the previous Q cylinders to the multiplier value; and

determining the offset value using one of a second polynomial equation and a second bi-cubic spline that relates the intake valve phasing parameter, the exhaust valve phasing parameter, and the cylinder activation/deactivation sequence of the previous Q cylinders to the offset value.