sorry for my ignorance guy

what the ecu?
Thanks

Electronic Control Unit, or the computer/brain of the car.

In the later model cars the correct term would be "PCM" or Power Train Control module.

It is the primary control module for the vehicle. In the rx8 it is located next to the battery under the ducting. It has it's own cooling fan ducting so make sure you re-install the cover after a jump start or battery inspection.