www.rx8club.com has tons of info and will answer all you questions.
The RX8 ECU is installed into the black plastic box on the front, passenger (US) side of the engine bay.
ecu?
buy a new one
Passenger side, under the hood, beside the radiator reservoir.You will see a black plastic cover about 6 inches wide by about a foot long, with three small bolts holding it down.The ECU is under that.
you'd have to get the tire size. It's on the tire itself.
check your coils for spark.if there ok replace the plugs and wires
You bring it to a mechanic..
replace ECU with identical ECU
The ECU part for this car runs $150 to $300. To replace it, it can run the cost up another $100 to $200 if a person does the replacement at a shop.
Well fiery thing you should do is get you mazes rx8 back because it worked in it
the ecu should be under the carpet on the passenger side. unplug the old one and plug in the new!