[TexasGator]

“Boeing’s engines have the technology to continue pinging, which they did, for another 7-8 hours after the transponders went off. “

The engines were Rolls Royce. They do not ping. Engine data is loaded into the aircraft data system which then conveys engine and aircraft data to the receiver. Weather data and pilot communications are also handled by the system.

[Lucky9teen]

Ok, maybe not "pinging", but data was being sent by the engines.

...one of the few facts that does not appear to be in dispute is that the Rolls-Royce engines on the Boeing 777 had an engine monitoring system.

There are numerous reports, that this "data", was still being communicated hours after losing contact.