Torque converter clutch slip control systems and methods based on active cylinder count

1. A torque converter clutch control system of a vehicle, comprising:

a target slip module that determines a target torque converter clutch slip based on an average number of activated cylinders of an engine during a predetermined period;

a slip error module that determines a slip error based on a difference between the target torque converter clutch slip and a slip of the torque converter clutch; and

a slip control module that controls a torque converter clutch based on the target torque converter clutch slip and the slip error.

2. The torque converter clutch control system of claim 1 wherein the slip control module controls the torque converter clutch to adjust the slip error toward or to zero.

3. The torque converter clutch control system of claim 1 further comprising a slip module that determines the slip of the torque converter clutch based on a difference between an engine speed and a torque converter turbine speed.

4. The torque converter clutch control system of claim 1 wherein the target slip module determines the target torque converter clutch slip further based on a torque output of the engine.

5. The torque converter clutch control system of claim 1 wherein the target slip module determines the target torque converter clutch slip further based on a gear engaged within a transmission of the vehicle.

6. The torque converter clutch control system of claim 1 wherein the target slip module determines the target torque converter clutch slip further based on a torque converter turbine speed.

7. The torque converter clutch control system of claim 1 wherein the target slip module determines the target torque converter clutch slip further based on a torque output of the engine, a gear ratio, and a torque converter turbine speed.

8. The torque converter clutch control system of claim 7 wherein the target slip module determines the target torque converter clutch slip using a mapping that relates the average number of activated cylinders, the torque output of the engine, the gear ratio, and the torque converter turbine speed to the target torque converter clutch slip.

9. The torque converter clutch control system of claim 1 wherein the target slip module increases the target torque converter clutch slip as the average number of activated cylinders decreases and decreases the target torque converter clutch slip as the average number of activated cylinders increases.

10. A torque converter clutch control method for a vehicle, comprising:

determining a target torque converter clutch slip based on an average number of activated cylinders of an engine during a predetermined period;

determining a slip error based on a difference between the target torque converter clutch slip and a slip of the torque converter clutch; and

controlling a torque converter clutch based on the target torque converter clutch slip and the slip error.

11. The torque converter clutch control method of claim 10 further comprising controlling the torque converter clutch to adjust the slip error toward or to zero.

12. The torque converter clutch control method of claim 10 further comprising determining the slip of the torque converter clutch based on a difference between an engine speed and a torque converter turbine speed.

13. The torque converter clutch control method of claim 10 further comprising determining the target torque converter clutch slip further based on a torque output of the engine.

14. The torque converter clutch control method of claim 10 further comprising determining the target torque converter clutch slip further based on a gear engaged within a transmission of the vehicle.

15. The torque converter clutch control method of claim 10 further comprising determining the target torque converter clutch slip further based on a torque converter turbine speed.

16. The torque converter clutch control method of claim 10 further comprising determining the target torque converter clutch slip further based on a torque output of the engine, a gear ratio, and a torque converter turbine speed.

17. The torque converter clutch control method of claim 16 further comprising determining the target torque converter clutch slip using a mapping that relates the average number of activated cylinders, the torque output of the engine, the gear ratio, and the torque converter turbine speed to the target torque converter clutch slip.

18. The torque converter clutch control method of claim 10 further comprising:

increasing the target torque converter clutch slip as the average number of activated cylinders decreases; and

decreasing the target torque converter clutch slip as the average number of activated cylinders increases.