One problem related to fuel injection has been reported for the 2004 Mazda RX8. The most recently reported issues are listed below.
Problems with rotary engine starting. Usually happens at a temperature below 25 degrees fahrenheit. Poor ignition system for colder weather. I have had issues with it each winter I have owned the car(2004 to present day). A trip to the dealer has been necessary each time and while the warranty is still valid, this is an inconvenience but it's after the expiration is when I worry. A recall was noted and repairs were completed the fall of 2006 but the same thing happened yesterday. This recall included spark plug replacement, battery replacement, starter motor replacement, and reprogramming the onboard computer chip for ignition changes. The new starter motor made significant changes to starting time but didn't change it's condition in colder weather. The Mazda dealer has been little help in resolving the situation. Their remedy has been just treating the symptoms and not figuring on a solution to the ignition problem. They have told me repeatedly that "these cars do not like cold weather" and "these cars do not like short trips". I would figure that if a combustion motor cannot start in temperatures below 25 degrees f, then they should offer a better car/motor replacement.