Hello, I just recently purchased a 04 rx8 with only 74k kms. The car was in great condition body wise but it had a p0302 engine code. The thing is, the code only flashes when the car is at idle/under 1500 rpm. Since purchasing it I've replaced the coils with oem mazda coils (revision C) changed the high tension coil wires, and changed the spark plugs. At this point I'm not quite sure what route to take. I'm considering switching the injectors from rotor 2 into rotor one to see if the root of the issue comes from those. I'm not quite sure what else to do. I spoke to a guy who regularly rebuilds his engine and he suspects the seals but I don't want to dive into a rebuild without being certain.

Last night, the car also flashed (for the first time) the codes : P0420 and P0300 so im starting to be a little more concerned with the issue at hand.

 

Can you check fuel trims on a warm idle? They should be 0, if not report back. Is the intake stock?

Guy who regularly rebuilds his.... Hmmm. If you do it right you shouldn't need to rebuild it regularly

For the p0420 get the cat checked visually inside . Poor ignition kills cats, cats kill engines.

 

Great question, ill check next time i drive it and post the result. As for the intake, it's stock, everything is stock

 

OK, so I drove the car last night, and the codes popped up again.
For some reason my OBD scanner won't detect the CAN protocol If the car is runnning so I had to turn it off, the STFT B1(%) was 4.7, and the LTFT B1(%) was 7.8. // this wasn't at idle, I assume it was the last reading before turning car off