I just bought an 06 honda Odyssey with 68000 miles. This is my first vehicle with any kind of cylinder deactivation system. I have read that the system should be transparent in its operation and the only indication that the car is operating on 3 cylinders is the ECO light.
I am getting a vibration when the van switches to ECO mode. I cant really notice it during slower speeds (ex. under 40 mph) but its pretty noticeable on the highway. As soon as I accelerate, the vibration is gone but returns again once the system switches back to 3 cylinders. It has the same feel as if you were driving a car with a manual tranny and shifted from 1st to 4th.