Rx8 maxing out at 107 mph
 

My rx8 is basically maxing out in 4th gear... I bought an rx8 and wanted to get a feel for it. I can redline up to 9000rpms in first, second and third gear, but then 4th gear it stops at 7000rpms and im sitting at 100-101 mph for multiple seconds, it never passed that line, then when i shit to try 5th gear it climbs to about 107mph slowly and thats it... 6th gear is basically OD and a **** show anyways considering its not pulling at 5th. Please let me know if this can be fixed or a common problem. I thought it could possibly be the governor,.. but why at 107mph....

That doesn't sound right. Since you're new to RX8s, there are some common things you need to get on top of:
- replace ignition coils if older than 30,000mi
- replace spark plugs if older than same
- check that the cat is not clogged
- do a compression test to assess the health of the motor

Full thread here: https://www.rx8club.com/rx-8-discuss...t-here-202454/

Are you towing a boat when doing this? If not then there could be many mechanical issues that would limit power/speed. Also, be careful about illegal driving/street racing posts, they are forbidden here.

There isn't a governor on a RX8. Top speed is aero limited on a manual transmission car to around 150 mph. And, electronically limited on a automatic to 125 mph.
I would think the first place to look would be the ignition system. Also possibly a clogged catalytic converter.

I replaced ignition coils, spark plugs battery and starter when i got. I am not towing a boat lol. Also yesi have engine codes about the catalytic converter, but I thought it was due to bad emissions.. How does that effect the driving other than gas mileage?

A bad cat converter can ruin your engine.

Clogged cat -> backpressure -> heat and unnecessary load -> dead engine.

As I understand it, a clogged CAT does not allow all your exhaust gases to escape and exit the tail pipe. As a result it is causing a bottle neck and backing up into your motor, which is not good. It is less than ideal in a piston engine, it is a death sentence to a rotary. I would stop driving it until I get it replaced. If you do a search, you can find multiple posts discussing this issue.

edited to add: All the above that beat me to it lol

ohk. I'm seeing that people are gutting their/making it cat less.. I don't necessarily support it, could I just take it off and clean it somehow?

No you cannot just clean it and have a working cat.

Your options are to gut it and don't replace it(wont pass emissions...), buy a aftermarket cat and have it welded in place(search, there are not many good replacements), buy a new cat pipe from mazda, or buy a midpipe and stay catless. As someone else said, do not keep driving the car as-is. You could turn a $200-1300 problem into several thousand if you kill the engine.

Depending on your state you may be able to pass without a cat on the car, if it is only the obd2 test then its possible. If they do the sniffer test then you need to get a working cat on there.

Alright thanks for all of your help. I am going to gut it out first then if I'm not satisfied I'll just buy a new one. The one last thing i want to make sure is though, is can the cat really take 40mph off my car, or would there be other things involved?

off topic and i apologize, but i thought it was aero at 150 in 5th and fuel cut off at 120 something in 6th


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Put duct tape over you mouth, block one nostril on your nose, and then go run around the block as fast as you can and tell me how that works out for you.

Hell, I gained about 40 HP from taking mine off (yes, it was that bad). It should be a night and day difference as soon as you roll out on to the street. A clogged cat, besides a crap ignition is a common cause for big power losses in these cars.

P.S. My exhaust smoked a lot for the first few minutes after startup with my cat-delete, don't be too alarmed if yours does the same. Leftover carbon and what not.

I dont think its been mentioned but do you have a JDM spec 8 as they are limited to around 170km/h or 107 mph, the engine will just stop accelerating, my first 8 was like this.

Hmm I have a similar issue, mine stops accelerating around 120mph (Manual)
I think I need to replace my coils as I replaced the plugs and wires not to long ago, did not have the money at the time to do the coils ^-^

Any advantage with BHR or will OEM suffice? I know BHR is amazing, top quality, will last longer, ect.. but for 500$ vs 84$ Is it worth it, for a normal street driven RX8?

BHR is better, but if money is an issue then just go with the aftermarket coils. There is also at least 1 DIY on how to make your own ls2 coil upgrade which would save you money if you wanted to go that route.

It's not a question of how you use it, its more of a question of not having to worry about it. The OEM coils will need to be replaced again in some time, and you never know exactly when they start to gradually die... that said, anything is better than old stock coils.

Sounds good loki, buying some OEM replacements, then saving for the BHR ^-^

Could it be an oil issue? Could your engine rev limit you because of improper oil intake, either it's not getting proper flow, or you don't have enough oil? I wouldn't let the oil drop below the second hash mark (1 quart low,) especially if you are really pushing the car. I know there is another pint to go before you hit the add mark, but I think that is too low.

You should find out where your car came from. I know the overseas 8s are less powered and limited on everything. So sounds like you might have one from overseas somewhere. I do not think a clogged cat or bad plugs or coils would cause this but I am no expert so dont take my word for it. I got my 05 8 to 164 before some jerk cut me off ( on the track) no street racing here no worries.

It's virtually impossible, for an individual, to import a car to the US and make it road legal.

May I ask what track?

Did anyone figure out if it was due to the cat? Mine did that today same gear (4th)

Still happening
 

this is happening with my car too
i have a punched out cat, the only code is a cat code and I already did coils and plugs and it still cuts power at 107mph until I let off the gas and go back on it