Since they are looking west of Malaysia I suspect they have ACARS data. But why is it kept so secret, or don't have any data, is a mystery.
Malaysian officials non-committal on MH370 ACARS transmissions - 3/11/2014 - Flight Global
.... acting transport minister Hishamuddin Hussein, he instead embarked on one of the search and rescue flights looking for the aircraft in the Straits of Malacca on Malaysia’s west coast.
Media reports have said that no ACARS data was received from the aircraft when its transponder disappeared from radar ....
... "All Malaysia Airlines aircraft are equipped with continuous data monitoring system called ACARS which transmits data automatically," says MAS. "Nevertheless, there were no distress calls and no information was relayed."
Presumably the aircraft would have transmitted ACARS data prior to its disappearance, but an industry source familiar with ACARS says this would be entirely dependent on the level of service ...