My Samsung s4 has no SIM card. Can I still locate it?
Unfortunately, unless there is some type of internet connection, which would be through Wi-Fi since there isn't a SIM card, it would be difficult to find the phone. Calling the cell phone service provider, giving them the IMEI number, and starting that the phone is lost would allow the service provider to black list the phone from being used on a new service plan. Other than this, I don't even think that Lookout Mobile's Plan B app would be helpful.
If it is somehow connected to a wifi network, you might find it by Android Device Manager/Samsung Dive/Plan B Application.
If not, I'm sorry but there is no way I know of.