So I've seen many people post on the forums about getting a cel for their catless exhaust. On my last car I avoided this problem by purchasing two spark plug defoulers. I had one milled out to 3/4" I believe. Then you screw the milled one into the normal one. Then you screw that into you exhaust and screw your o2 sensor into the defoulers. Never got a cel with no cat for two years. Granted, my last car was a 97 Sunfire. So maybe a trick like that wouldn't fool an rx8. Anyway, here's a link to the defoulers I purchased in case anyone is interested.

 

Are you saying that this worked on your Sunfire for 2 years? or are you saying that this worked on your RX-8 for 2 years?

I ask because anti-foulers have been proven not to be effective. They DO prevent P0420 (Catalyst below efficiency), however they cause P0139 (Rear HO2S circuit slow response) at a minimum, and possibly one or more of a number of other CEL codes. So it "works" in that you don't get the CEL for no cat, but the ECU is too smart and knows that the O2 sensor isn't responding correctly properly to periodic commanded behavior to ensure that it is in the exhaust stream properly, so it still throws another code and blocks you on emissions that way.

The only proven method to block the CEL codes for no cat is to reflash the ECU and literally "turn off" the ECU's ability to even test for it. Which is doable with the AccessPORT or MazdaEdit.

 

I was saying it worked on my Sunfire for two years. I'm a new rx-8 owner. I didn't know if this had been tried with this car or not. I hadn't seen anything about it and I have seen a lot of people complain about the light. Thought maybe I'd try to contribute as a new member!

 

I put one on my 8 when I put my mid pipe on. It made me pull a 420 code. Pulled it off and 420 code went away no codes shown at all now.

 

^ Yes. You are actually less likely to get a CEL if you don't try any tricks than if you do try them.

 

When my car was catless, it would only pop a cel when I launched it or dropped in to 6th gear. If I drove normally and avoided 6th, it wouldn't pop a code.

 

these spacer work sometime and sometimes they dont ive even seen them work on one model car but not on another car of the same model.