One problem related to engine clicking and tapping noises has been reported for the 2004 Mazda RX8. The most recently reported issues are listed below.
I purchased the car in 5/14/2013 after a week or so it started to lose power and misfiring , popping noise, transmission warms up. The gear that I hold and shift just warms up all the time it feels like it might fire up. Then I took the car to a mechanic they couldnt do anything. I took it to Mazda mechanic they charged around 900$. Then it didnt fix anything I went another one and they told me loss compression it was 115 that time. I kept driving it and they said I need to rebuild the transmission too. . I paid this car 6500. And now it s all bad. And apperantly I need to buy new engine and transmission. I believe it will cost me about 6000$ . Now its on 129000miles.