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rx8 rough idle nd sluggish power

Old 06-21-2011, 05:22 PM
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rx8 rough idle nd sluggish power

hi guys jst like to say great to be part of the club love ma new rx8 couple issues though i was rearlly hopin to get some experienced views, since i got my 8 a few weeks ago ive noticed it rough idles when warm and seems sluggish power when warm engine managment light has come on and gone offa few times too, its rearlly frustrating any help would be rearlly appreciated was thinkin about worst case low compression but she starts everytime without fail hot or cold????? plz help cheers.
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Old 06-21-2011, 05:37 PM
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Never fear, Jedi is here!

1. congrats on purchasing the RX-8
2. welcome to the clut.....errr.... "club"

In order to help remote diagnose, we'll need a few more details on the car.
year?
miles?
does the vehicle appear to be modified? (does the intake box look 'stock', exhaust upgrades, etc)

First and foremost: you should have that Check Engine Code read either by a shop or a local auto parts store. Depending on what part of the country you're in (or WHAT country you're in), some places will do it for free.
Once you have the CEL code, you can see this thread which has every code listed for an idea of what might be causing the issue. https://www.rx8club.com/series-i-tech-garage-22/rx-8-technical-info-cel-codes-pcm-pin-list-collision-guide-26291/

Did the light stay solid or did it blink?


Without knowing any of that information, here are things that could possibly be causing your issues.
1. bad ignition coils - a known weakness of the RX-8. If you do not know how old they are, consider replacing them with new coils (very easy to do on your own) or you could consider an aftermarket upgrade. (BHR coils are pricier but you will probably never need to replace them)

2. clogged / broken catalytic converter. It is possible that the vehicle can detect this and give you a CEL but the easiest way is to have a mechanic (or yourself) loosen the three bolts that connect the cat to the exhaust manifold and peak inside. See any pieces bouncing around? Can you hear the ceramic moving? If so, it's busted.
Again, depending on your location (which I recommend you update in your User Profile settings) it could still be under warranty or might need to be replaced. OEM is VERY expensive, aftermarket is much cheaper.

3. low compression.

Last edited by Jedi54; 06-21-2011 at 05:42 PM.
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Old 06-21-2011, 05:38 PM
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when was the car last serviced? How many miles on engine? Any mods on the car?

check these things:
plugs/ coils
catalytic converter
MAF/ eccentric shaft sensors
Air filter.

edit: Jedi and his mind tricks...
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Old 06-21-2011, 05:42 PM
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too slow you are my young Padawan.
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Old 06-21-2011, 10:39 PM
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Jedi I thought you didn't need codes read? I thought you could just use the force.
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Old 06-22-2011, 12:21 AM
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Originally Posted by Silver6 View Post
Jedi I thought you didn't need codes read? I thought you could just use the force.

Ha ha ha! He may just have to read it in his head...lol
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Old 06-22-2011, 01:17 AM
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Originally Posted by Silver6 View Post
Jedi I thought you didn't need codes read? I thought you could just use the force.
I don't need a code reader for such things, the OP however is but a mere mortal.
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Old 06-22-2011, 12:05 PM
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Originally Posted by Jedi54 View Post
I don't need a code reader for such things, the OP however is but a mere mortal.
I have a lot to learn master jedi
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Old 06-22-2011, 01:15 PM
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thanks evryone

thanks very much for all the speedy replies mch apreciated its a 2004 192bh its done 67000 miles next service is at 75000 miles its not been modified in any way as far as i can see it has a racing beat oil cooler hose set the last owned told me its had a new cat not sure how long ago though its had all the services done on the dot,the engine managment light is solid not blinking im gonna get it in for a diagnostic on saturday hopfully also it makes a rather loud noise when im accelerating beetween 6000 and 7500? any clue about that thanks again everyone.
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Old 07-14-2016, 03:05 PM
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Hey, guys. I found a thread with a similar problem to mine to post.
My Car:
Mazda rx8 2004
72k miles.
Before the breakdown. No hotstart issues.
Ran perfect. Started up on a dime.
No check engine light. Some rough idles on occasion..
I have driven it right...Redline once a drive yada yada....

Problem:
Broke down a couple days after oil change. Immediately towed it back to the garage and thought it was just realllly flooded so I changed the spark plugs, coils, cat and wires and deflooded. It starts but now there is a small backfire and it runs very very sluggish and idles just as bad... Also even after 20 break stomp and other resets there are still no engine lights... I have exhausted all of what I can find
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Old 07-14-2016, 04:12 PM
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"Broke down a couple days after oil change".

This could be the infamous "overfill" of oil. Check your maf/iat sensor to make sure there's no oil on them (unplug the battery prior to work). Check your intake tube for oil and check the throttle body. Report back with your findings.
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Old 07-15-2016, 02:46 AM
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Originally Posted by RX8Soldier View Post
"Broke down a couple days after oil change".

This could be the infamous "overfill" of oil. Check your maf/iat sensor to make sure there's no oil on them (unplug the battery prior to work). Check your intake tube for oil and check the throttle body. Report back with your findings.
Good deal. I will let you know by the end of the day today. Thanks for quick reply!
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Old 07-15-2016, 11:01 AM
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Hello again, So after 900 dollars and no solution my mechanic decided he gave up and didn't do what you suggested ( I think he may of thought I was blaming him for an oil overflow). Would you happen to have a DIY on the items you suggested... I called my nearest mazda dealership, and the had suggested I start with a compression test.
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Old 07-15-2016, 11:09 AM
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Don't take offense to this post
clean maf

Use the method posted to search around
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Old 09-24-2016, 03:08 AM
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Rx8 rough running and no idle

Hi I have just bought a 2007 rx8 192 5 speed manuel with 80000 miles it has started running rough and no idle and cat glowing red
And below there is a list of Wat I have done so far but now I don't know where to check now any help will mostly appreciated...

So far I have


New coil packs
New spark plugs
New plug leads
Gutted the cat
Full service
Cleaned ssv valve

After doing all this I tried resetting Ecu with the 20 brake pump and wen I put diagnostics on the car there is no fault codes
No engine management light flashing or staying lite that's Wat is confusing me cause if there's a fault it should show on diagnostics .......
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Old 09-24-2016, 07:39 AM
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Was the cat intact?
If it was broken up, sometimes pieces get stuck in the catback pipe or muffler.
Rough idle when cold could be a vacuum leak.

Fuel delivery could be an issue, clogged injectors or the fuel pump could be dying.
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Old 09-24-2016, 07:47 AM
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Originally Posted by BigCajun View Post
Was the cat intact?
If it was broken up, sometimes pieces get stuck in the catback pipe or muffler.
Rough idle when cold could be a vacuum leak.

Fuel delivery could be an issue, clogged injectors or the fuel pump could be dying.
Cat had started to brake up so I knocked it all out pipe all clear haven't checked the back box yet and have checked it all for vac leak and nothing the main thing that is doin my head in is that there's no fault codes at all so I don't think there's anything up with the injectors as it would pop up a fault code
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Old 09-24-2016, 06:16 PM
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Stock intake?
Did you clean the MAF sensor?
Check the air filter and intake for oil from overfill or blowby.
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Old 09-26-2016, 07:19 AM
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Originally Posted by BigCajun View Post
Stock intake?
Did you clean the MAF sensor?
Check the air filter and intake for oil from overfill or blowby.
Yes everything has been checked cleaned
No oil in air filter or intake pipe
I have now replaced the crank sensor
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Old 10-04-2016, 04:50 PM
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Okay, i can't for some reason open a thread so imma tag along for this one.

I have a 2006 rx8 driven roughly 100k KM, had the oil change recently and the air filter. About 3 days after that mid drive, the car suddenly lost power and the CEL blinked (it's already on from the cat being gutted by a previous owner). I immediately drove the car home as i was a short ways away.
Upon trying to restart the car the battery had died due to me leaving the interior light on for about 3 days (i know, i know, stupid me). So i charged up the battery with an external charger and started the car up. The car was really sluggish, had a hard time idling and after about a minute running started backfiring so bad i immediately shut it off.
Now, the car's due for a sparkplug and coil change anyway so i'm doing that as soon as i can tow the car into a garage. I'm wondering though if this problem could be explained any other way.

The car has had a hard time starting, takes about 2-3 seconds to start up while turning the key. And it acted this way regardless of weather or not it was cold or at ideal running temp.

Any ideas?
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Old 10-31-2016, 08:40 PM
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Just got my first rotary and she has started running rough. She hesitates to start up then the idle jumps randomly. When I try to apply throttle she is able to rev up but she is having a hard time doing so. Had my engine light checked and the code was p0300. Changed my plugs and noticed that the trailing plug on cylinder 1 was black. Haven't tried changing my coils yet so I was wondering if that might be my main problem. She is bad enough to the point where I can't be driving around at all. I have an 05 with 99938 miles on her. Also at one point she started smoking while my mother was driving her. If anyone has any advice, it would be greatly appreciated.
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