Hey guys, I'm new here. I'll try and explain this the best I can. I purchased a used 04 GT 3 weeks ago, with 55k kilometers. After 3 days of owning it, it threw a CEL. I brought it into the dealership the next day and they ended up replacing the CAT (still under warranty thank god).

Since then I haven't got a CEL, but notice that while driving before the engine gets warmed up it shudders and bogs (best way I can explain it). For example, I'll get going in 1st gear, give it some gas, and the car just doesn't want to go. It feels as though the engine isn't getting any gas? This can be scary, especially when pulling out into traffic. Once the car gets warmed up, I never have this issue. I'm scheduled to bring it back into the dealership this week, but just wanted to know if/what I should expect them to tell me what's wrong? I even asked the service manager about the possibilty of bad coils, but he said it would have thrown a CEL, is this right?!? Any thoughts/opinions would be much appreciated!

I would go with coils and spark plugs and worst case new engine

Thanks for the info. I know plugs wouldn't be covered under warranty, any idea about the coils?

Coils are only covered under basic warranty.

I'm not dipping my toe into a vendor debate ;), but if you search this site, there are ways of adapting General Motors coils to the RX-8 harness. Reportedly, this is a better solution of both longevity and spark output.

Whatever you do, coils are a straightforward DIY job. You will also want to look at / change the plug wires while you're there...

or if you want i have some OEM coils and spark plug wires for sale with like 1k miles on them for sale 110 shipped

If it isn't the coils or the plugs, I think it would best to say that your seals arent expanding properly, but dont take my word for it...

Did your CEL flash at you?

If it isn't the coils or the plugs, I think it would best to say that your seals arent expanding properly, but dont take my word for it...

Thanks for the advice

Did your CEL flash at you?

No, I've yet to see a flashing CEL either.

Flashing CEL means misfire which doesn't rule out that your plugs and coils are ok but would be a symptom of failure. Now, the person you bought from might have cleared the code but I would have expected it back before 3 weeks. If the cat was damaged and replaced it is possible that further damage was done to the engine, keeping it in limp mode. Hope your dealer can figure it out and get you up and running normally again.

Well, to add to this I've noticed that under load in 1st gear, it takes forever to reach 4-5k rpms, then it kicks in and goes. It's also noticeable in 2nd but not as much. So you guys think this sounds like coils?

That makes it sound more like your VFAD is stuck open or you have a vacuum leak.

That makes it sound more like your VFAD is stuck open or you have a vacuum leak.

Hmm that's interesting. I'll have to get them to check for these things also. Unfortunately the dealership only seems to look at what I tell them too....not very proactive if you know what I mean. Thanks again.

eayest way to fix a cat is to cut it out, unless u have to have a exhoust check where u live its the best way to fix ur problem and it gives u more power and better sound

easyest way to fix a cat if to cut it out

eayest way to fix a cat is to cut it out, unless u have to have a exhoust check where u live its the best way to fix ur problem and it gives u more power and better sound

Thanks, but the CAT was just replaced.

Well, had it in to Mazda today and they found all 4 plugs were bad, and had them replaced. They did compression, fuel pressure, and full exhaust test - everything here checked out OK. They did however find 1 bad coil, and the wires are bad (thankfully these are being covered under warranty, whew!). While the replacement coil is on order, they swapped the bad one to a trailing position? Not exactly sure what they mean by this, as I picked the car up after the service dept had left for the day.

But one thing I can say now is WOW, this is how the 8 is supposed to run! I couldn't believe the difference off the line, it pulls so much better now and the throttle response is instant. I can only hope the new coil and wires make it that much better.

One more thing, I was getting ~14mpg, should I notice an increase in mpg after all this?