I just bought a beautiful 2009 Rx-8 with 65,000 miles on it and occasionally when I'm driving it won't go past 5,000 rpms on occasion, mainly after longer drives. I dont believe this to be a compression issue since it has no problem with warm starts. I'm thinking it may be a clutch issue based on the research I've done but I would like to see if it could be anything else.

 

A failing clutch would present as rpm climbing without corresponding increase in speed. What exactly happens when you try to accelerate past 5?

Does it stumble or remain smooth? Does it go past 5 easier if you go full throttle or if you creep up on it?

 

It stumbles and doesn't like accelerate once it hits the 5,000 RPM range I haven't really tried pushing it once it starts doing this just incase it causes further problems. Also as a note I forgot to put in the original post is it isn't causing a check engine light to be thrown

 

Limo mode? Omp failing?

 

I think that might be the case now, but in the threads I've read about limp mode they normally throw codes which mine hasn't

 

5000 is a weird one. No valves open in that range. The VFAD opens, but even if it didn't, I wouldn't expect it to choke your engine.

How is your catalytic converter? I would expect a code or 3 if it was blocked to the point of preventing you from accelerating, but stranger things have happened.

What about ignition coil age?

 

My omp didn't throw a code. Unless my reader wouldn't pick it up.

 

I'm not sure about the condition of the cat, I'm pretty sure the exhaust system isn't stock and if it is the previous owner did modifications so I plan on replacing the whole thing, not sure about the ignition coil age I just bought this a few days ago.

Picture of what ever they did to the exhaust

 

I'll definitely make sure to replace it, it seems to be either that or the cat

 

Limp mode is around 3000 rpm though. It's really limp, you're not going anywhere with that. If you're getting up to 5, it's probably not that. Have a look at the cat. If that doesn't lead anywhere, let's get some OBD data on air flow, fuel trim, afr and demanded afr when the issue presents.

 

check to see if the SSV is either stuck or not working due to lack of vacuum in the solenoid tank. Primaries only is going to be starving for air at 5000 rpm. Especially with a maybe less than ideal compression engine.

A partially clogged cat converter could be another possibility.

 

The check engine light finally came up and I got the codes P0410 and P0411. I've read the P0410 and P0411 will both pop for a bad Cat so I'm definitely thinking its narrowed down to that. But I'll check up on the SSV to make sure thank you

 

Those codes are actually for the air pump. Possible the previous owner removed it or it has jammed. The air pump is normally only active during a cold start, not needed for continuous operation.
Definitely inspect the cat still, since the car is new to you.

 

I was driving and it lost power and ended up stalling out

 

if it’s a bad cat converter and you keep driving it, then you’ll need a new engine soon too, assuming it’s not too late already.