Running rough after it gets warm? Coils?
 

I've got an '04 4AT with about 55k miles. I've noticed that when I drive for more than 15 minutes or so it'll start running rough. Doesn't like to sit and idle (RMPs drop when the fan cycles, and it shudders for a bit until the engine speeds up again), and sometimes when I accelerate hard when it's starting to run rough I get some exhaust sound that I take to be fuel burning in the exhaust system.

CEL is on with a downstream ox sensor code (I have the new sensor, just have to put it in), but it acted a bit like this before the CEL came on. It's worse in warmer weather, and it's getting worse lately.

I had the plugs and engine mounts replaced when I got it 1.5 years ago, but the coils are at least that old.

I'm figuring it needs coils. Does that sound right? Or should I check something else before I go with new coils?

coils
 

i also have 2005, 44,000-45,000, auto paddle. thay say it is best to replace the coils at 30,000 mi.? & should replace all at once. done mine, but now im haven hot starts. iam going to have a compression check done.

does it sound like marbles in a can? if it does theres about a zillion posts on it with about as many theories on why. Could be a sensor, plugs/wires/coils (and yes they should be changed every 30k like the manual says), it can be about anything really. mine personally was a plug/coil/wire issue the first time, and a vfad the second time. compression is also an issue. are you having hot starting issues? in all likelyhood that downstream o2 sensor is getting burned out due to a rich mix and the fuel not burning off. could ruin your cat too btw. also look into doing a seafoam treatment. deal with it quick or your looking at some expense. cat replacement is over 700. keep running it like that, and if its not a compression issue it could turn to one, and your looking at thousands. oh wait your a lucky son of a gun who still falls under the 100000 mile powertrain warrenty. take it to a dealer like munchyboy and join over half the members in here on the second motor club.

No, I haven't heard that yet. It only makes three unusual noises. The secondary air pump squalls a bit when it's cold, there is a faint drowning bird sound at low rpm when cruising (kind of a quiet burbling whistle. Happens at around 2000 rpm at constant speed, goes away with more or less throttle. no idea what it is), and then the pop/snap sound of unburned fuel igniting in the exhaust system when it is hot and under full throttle at high RPM.

I figure that if my coils are weak, then that full throttle high RPM condition is where I'd be most likely to get enough unburned fuel to ignite like that.

Hm. I wonder if weak coils would be the reason I've started having issues with the oxygen sensor?

It starts harder when it's hot, but not as hard as when I cold start then turn it off without letting it warm up. That usually involves twenty minutes of pulling fuel pump relays and cranking the engine.

I hope four months is quick :sad:

I figure I'll get the new sensor and coils in, then seafoam it, and then see how it acts. Hopefully it'll start and run nicer, and the CEL will go away, and a bit more performance would be nice too.

Nice. Is there a time limit on that warranty? Because at my 6000 mi/yr rate the 45k miles left on that would last a long time.

not sure. i think 10 years. i could be wrong. put it the search and you'll find it. I know the bird sound you speak of. Im very surprised you haven't gotten the miac. you will soon. id put money on the coils too. and yes if you're not burning the fuel well then it could foul out that sensor. You could have fouled out a plug too even tho they are new. I bought my car originally with 32k on it, and didn't realize the plugs and stuff were never changed. i started to get that noise and problem around 55k. i replaced coils/plugs/wires/battery and fixed it. i'd still do the seafoam tho. couldn't hurt. good preventative maintenance as well.

tip: instead of pulling relays you can hold down the gas pedal. it shuts it off.

birds
 

that bird chirpen is one or more of the coils, on the bottom of the coil u will see white burn marks. call the main usa dist. give them the vin#, if u are under warrenty take it to the dealer, u might get a new engine! :) that warenty is 8yr. 100,000 ml. check it out soon, not much time on that one.

Well, crap. I was hoping it was something easy. A new engine would be pretty sweet, but I'm not usually that lucky. Warranty probably expired last week.

I emailed Mazda about it to see if they can tell me if it's still in warranty and if I should take it somewhere to have it checked out. If I don't hear back soon I'll call someone.

It would be really weird to own a product that the company stands behind, I usually just get screwed on this stuff.

Thanks! I'll update with what I hear back about it.

Clean MAF, reset EES, replace plugs, wires, coils.
And do research on your warranty/car.

Mazda says "your vehicle is no longer covered under any factory warranty. The Rotary Core Engine Warranty Extension expired as of 9/25/2011."

No surprise there, like I said, I find it extremely rare to have a product that the manufacturer stands behind when needed (when my stuff breaks, it does so shortly after the warranty expires).

So, new coils to start with.

What's an EES?

Probably meant ESS - Eccentric Shaft Sensor.

Ie - the 20 brake pedal stomp that causes the oil pressure gauge to sweep.

Do that, and see if things improve for you.

BC.

compression
 

my old rx-7s had a 4 barrel, one day it would run great, & the next it wouldnt even start cold. it spun so fast it sounded like all 4 plugs were out! no compression. ther were a few ways to get it going,. one was to pour atf down the primaires. then i found out u can take a coke bottle, put some gas & atf in there & shake it up. pour it in the carb, after a few seconds she fired up. it would last for a few months, some times longer. somewhere on here is a therad on this for the rx-8. if i knew more about computers i would gladly tell u where. so people when i say i searched & found nothing its not becouse i didnt try.:scratchhe

Tried pumping the brake 20 times, but no oil pressure indicator sweep.

Maybe it has the older ECU firmware?

If your coils are old. Then it's possible that the Catalytic Converter is causing the issue. Misfiring coils cause unburnt fuel to overheat and clog the Cat. This causes a restriction in exhaust flow and rough idle, loss of power. More evident at higher RPM's.
As mentioned. Clean the MAF sensor too.

Coils and plug wires ordered. I'll clean MAF, check the plugs and install the new O2 sensor when the parts get here.

The plugs only have about 5k miles on them, so hopefully I won't need to get a new set.

If the cat is clogged, can anything be done about it short of replacing it?

The only high RPM issues I've noticed is when the coils are hot and it's at WOT, I can hear fuel burning in the exhaust system. This has only happened about three times, but it seems likely that plenty of fuel is going through.

Engine core is 8 years / 100,000 miles. Did you not know this when you bought the car? How long is a manufacturer expected to cover the car?

I don't know about anyone else, but when my engine core warranty is approaching expiration, I will be deciding whether to sell it, or keep it and put away some money for a day when the engine needs replacing. A $5000 engine for a car I really love is a reasonable trade-off vs $30,000 for a new car that I may not like quite as much.

Post #4 in this thread points out that he didn't have a clue about the warranty.

Just boggles my mind that people don't do any research on a car before they buy it.

He could have checked it out before the warranty expired, and changed his fate on that always missing out on warranty coverage he complained about.

BC.

Sorry, snark doesn't always come across in text.

I don't expect any support from the manufacturer, nor did I at the time I bought the car.

But thanks for your input.

ya i wish i would have waited longer personally. i got my 04 in 06. Not that many known issues then. Just a few. and when it was released all of its reliability issues were supposedly fixed in the new renesis motor. bunch of horse dooky. I've never seen any car this prone to engine failure. If i would have known this before hand i would have never got the car. Mine is getting traded in next week for whatever they give me for it. Its barely starting up anymore and im tired of pumping money into it when i know its a compression issue and not going to get any better without a new engine. . . and i still owe on the 6 year loan. yay. i love how it handles and looks, love the transmission, just wish it had another motor option... like whatever they are putting in the new v6 mustangs lol. id trade my rotary for 300 hp 30 mpg motor no problem. sorry for the rant.

It does seem to have some reliability issues. I did some research on it before I bought it, but not enough to understand how common the engine replacement problem really is (it's easy to encounter selection bias on those kinds of things, people have engine problems are more likely to mention it, so it's a little difficult to quickly judge how much of an issue something actually is).

I was trying to deciding between a Mazda3, and an Altima 3.5 to replace my old Geo Prizm which had died a few days before. I mostly drove the RX-8 because it was there on the lot and looked like a chance to have some fun. Did some research on it for the next couple of days and decided it was the one. I figured it would have some issues, and I knew I was making a somewhat impulsive decision, but what the heck, I usually get 5-10 years out of a car, and I'd been driving a crappy car for a long time, so it was kind of a now-or-never proposition.

Speaking of different power plants, I think I'll go see what people have done for electric conversions on the RX-8.

Wow, car parts suppliers are serious about performance. I ordered my stuff mid-morning on Friday, and it was in my box at 8:30 Monday morning :D

Here's a short video of how it starts up after about 10 minutes of driving. Not exactly hot, but warm enough to show how it acts. This is probably one of the worst starts I've seen from it, usually it just cranks a bit and catches, not sure what's with the hunting.

That was the last time that set of coils will start the car :icon_tup:

Installed the coils and wires, cleaned throttle body and MAF. Made a nice difference. Starts better when it's warm, idles without issues, and feels like it's got a little more spirit.

Chirping birds are still there though, louder than before if anything. Seems they annoy other RX-8 owners too though, judging by the forum posts about it. Maybe I'll track it down at some point, but it doesn't seem to be a problem.

Oxygen sensor goes in this weekend. Hopefully the CEL will finally stay dark. Gettin' tired of looking at it.

Check your cat while you replace the oxygen sensor.
I hope the "chirping" sound is just the cat, even if you don't describe it as the usual marbles in a can.
If it's pinging instead that's bad.

As much as I've read about the MIAC sound, I haven't heard a recording of it. This is more like the sound of a sports whistle (the kind with the ball) blown very softly.

Doesn't seem to be directly linked to engine speed, I've heard it from 10mph up to about 40, and it is pretty much unchanged through a shift.

my 8 wont even start that good cold. & once it is warm i dont shut it off unless i have an hour before i need to use it again. man i miss my rx-7s!!! much easyer to work on.

Here is my chirping sound, maybe someone will recognize it.

Does it only when it's hot. It's louder now than it has been in the past.

Also, here's a comparison of starting before the coil replacement, image of the coils, and hot and cold start after replacement.

I'm starting to think this is an exhaust leak. It's been getting worse, I can hear it now when the car is just sitting idling. Guess I'll have to get some hose and see if I can track it down.

Edit: I wonder if this could be a vacuum leak?

Also, after replacing coils and wires the car is still running rough after warming up. I've stalled it a couple of times. I have to be careful to turn the AC off before stopping for lights.

Glad I caught this - was about to change my coils for the rough after warm up issue. Sounds like we have the exact same thing going on. And I'm in Texas, so turning off the AC when I'm at a red light is becoming a very uncomfortable option. Is your problem worse when the fuel is low? Mine seems to be - wondering if it is a fuel pump issue.

I see a few threads about this, but not much about getting it fixed.

I haven't noticed any correlation to fuel level, but it is worse at times. I'll watch and see if there is any link. I'll add fuel pressure to the Torque log too, maybe that'll catch something interesting.

Have you tried seafoam? Another thread suggested that carbon buildup can make the apex seals stick a bit, which can cause loss of compression and rough idle.

I'd like to give it a try, but I'm reluctant to generate the clouds of smoke. If I wait a few weeks I can do it in the evening on the 4th, and nobody will notice :D

Testing for coil failure: Buy a coil tester from a local auto-parts store for $8 to $15 (looks like a sparkplug with a clamp on the side), with the car off, remove a plug wire from a plug, plug it on the end of the coil tester, clamp the coil tester to something metal to ground it. Start up the car and let it idle. The spark showing should be clear and steady in color and brightness and frequency. Test with each plug wire end. If you get one where it's unsteady in any of the 3 ways, then swap that plug wire with a plug wire that have you a good result, so you can rule the plug wire out.

Testing for vacuum leak / MAF issues: With an ODB2 reader / logger that can see STFT (short term fuel trim) and at least to 1 decimal of MAF g/s (mass air flow grams per second), log and inspect the log or watch your STFT and MAF g/s while at idle. If your short term fuel trim is outside of -1% to +1% then there is something wrong. A negative value means that it's pulling fuel, because it sees that the engine is running rich. This should be accompanied with a MAF that is greater than about 5.5g/s to 6.0g/s, and would suggest a dirty MAF. If your STFT is positive, it means that it's seeing the engine as lean, and adding fuel. This would be accompanied with a MAF of less than 5.0g/s or so, meaning your engine is pulling in air that isn't passing the MAF, so the ECU doesn't know to add fuel for it. You have a vacuum leak.

Wow! I have that exact sound (bird chirping). It's only at low speeds, right?? And....if you go through a drive-thru it echoes a lot louder off the side of the building?? lol. It may just be me but I listen for motor/exhaust noises when I go through a drive-thru. haha.

Anyways, It's very annoying. I plan on checking it out tomorrow. I was thinking it could just be a belt but now Im re-thinking that possibility.

I also have the same issues in my '04. Rough idle/trying to stall/increased with A/C/No power and hesitation when taking off from a dead stop.

Only thing is...My issues just started today and I've yet to get a CEL (knocks on wood)

Yep, that's it exactly! It starts out subtle and gets worse. I hear it all the time now, which I hope will make it a lot easier to find!

Let us know if you find anything, sounds like these issues aren't uncommon.

Notice this sound?? Of course this was only in park.

Car is not really running bad right now. Of course that's just right now, lol. Cleared ESS/Room fuse and visually inspected vacuum lines...no problems that I can "see". About to clean the MAF which looks dirty as hell and also going to spray the belts a little to eliminate that issue. :banghead:

Just drove it down the road to the parts store. It's idling "ok" but not perfect. The A/C is definitely not running right....(cool, warm, cool). It blows colder at higher RPM. Hmmm.....

Right now I'm going to clean the MAF...

Try some belt dressing just to make sure it's not creating any noise...

Put my airbox walls back in place... (It over 90 degrees every day here and maybe that will help with the idle)....

Do this A/C mod:

AC Amplifier Re-Program
Helps poor AC performance.
Notes: Procedure states that it only changes the air source. Many have said that it does more than that. I used a temp gauge and saw lower temps after, as well as reduced A/C cycling.
Best DIY is … https://www.rx8club.com/showpost.php?...24&postcount=3

To save clicks, the basics are here:

1. Verify ignition switch is in OFF position.
2. Press and hold the front defrost and air intake selector buttons simultaneously.
3. Turn the ignition key to the "ACC" position for 3 seconds. (Continue to hold the buttons down from step #3.)
4. Turn the ignition key to the "ON" position for 3 seconds. (Continue to hold the buttons down from step #4.)
5. Successful programming will be confirmed by the rear defrost indicator light flashing 3 times. NOTE: If vehicle's battery dies or cables are removed, the programming will not be retained and must be performed again.

Add some Lucas Fuel System cleaner and top off on gas (Possibly bad gas??)....

Reset ECU/fuel trims...

And finally, take a little road trip and we'll see what happens.

WOW! A lot smoother!!

My MAF was dirty as hell and had oil deposits all over it.

I took it on about a 5 mile trip driving it pretty hard, and a little slow at times. With A/C blasting. I;m proud to say I have no more idling problems, even with the A/C on. (knocks on wood) Hopefully, this solved my main problem.

I still have the chirping birds and It has nothing to do with the belts as I can tell. Hmmmm.....You said you replaced the coils?? :wallbash:

And...my A/C still might not be working that great but it's much improved. (hopefully the mod helped it a bit) It also doesnt help that the ambient temp is readin about 97 degrees out.

Either way, after doing the above mentioned, my car is running a lot better!! :yelrotflm

I'll post a video soon showing acceleration and idle....keeping my fingers crossed!

Oh wow, that sounds soooo much like my "What is that tinkling sound the engine makes?" at https://www.rx8club.com/rx-8-discussion-3/what-tinkling-sound-engine-makes-218482/

Maybe some clues in that thread. I dunno though, I've never figured it out. Mine isn't loud enough to be recorded, and it only happens now and then. But it was there before and after swapping the engine, coils, plugs, wires. fixing a heat shield and replacing my front end links.

EDIT: I was kinda convinced it was just transmission noise, but I see you have an AT... and mine is manual. Hmmm. I dunno then.

bump...

So, I've come to the conclusion that that rotaries simply are a pain to diagnose!!

Anyways, my issues still persist. Noise is still the same. Basically, the cooler the weather....the better my car runs. A/C makes the symptoms ten times worse. It ALWAYS cranks fine....idles and runs fine for about 10 ten mins in hot weather....then this is exactly what happens after ambient air temp goes up:

BTW....still no CEL

Coming to a stop (after say, a highway run) the brake pressure fades as if the car is dying. ( Actually tries to buck a little ) No...this is not brake/rotor related.

After I come to a complete stop (with A/C on) the idle starts to surge from the fan cycling with A/C. It will fluctuate from about 300 RPM- 1000 RPM and back down the 300. It "feels" like it's going to stall but NEVER does! When it dips to 300 there is a LOUD fluttering noise and BAD vibrations (sounds like a loud exhaust leak or maybe SSV) that are NOT there when idle is smooth or A/C is OFF!

When taking off from a dead stop it will hesitate badly....almost too dangerous to take off, or pull into traffic with A/C on. Very little power until it revs up a little. When I get going it runs perfectly fine.....this only happens at low speed/stop.

Also, the bird chirping is still there. This was not fixed by changing the coils as I thought. Also, there is still a slight ticking (valve ticking) sound. I suspect maybe from carbon build-up??

Things I have done in the past few months:

Cleaned MAF (x2)
Cleaned ESS
Changed Coils/Plugs/Wires
Inspected all vacuum lines
Reattached FAD to airbox and checked filter
Cleaned Throttle Body/Butterfly
Had injectors cleaned
Ran fuel system cleaner (x2)
Inspected intake for oil (none)
Regular Oil changes + adding (normal)

Things to try: (no particular order)

Possible CAT (no power loss at high RPM though)(Replaced in '10)
Check SSV
Compression Test
Fuel Pump
Seafoam
Motor mounts
Oil metering/injectors
coolant problems
Prob a few more I cant remember

I'm baffled by all of this and it seems to be VERY common with no definitive answers. It's always try this....then this...maybe this will work. This is too common after doing many searches. Im just surprised there's not a know-it-all Guru in these forums. Does anyone know what the problem is?? After all....'04's are the MOST prone to issues.....and this car has been around for about 8 years now. Very frustrating....

You have asked this before, and we have already told you what to do.
You have it listed in your list of things to do, but you have simply chosen not to do it yet.

Again, I believe you have MULTIPLE problems all at the same time, hence the reason why you can't track it down to just one thing.

Problem with stutter at idle that is worse with the A/C on - Neutral position switch and/or bad motor mounts. Could be one, could be the other, could be both. Its up to YOU to test it, and figure out which one is the problem. Been mentioned before, and in many other people's threads.

Better performance in cooler weather - compression.
Low performance at low rpm - compression.
Low performance at low rpm - stuck SSV valve.
Surging at idle - compression.

Seriously, how many times do we need to tell you this?
Just take your car in for a compression test already.

BC.

I've heard of the ticking sound being related to the rear shaft seal...
Poor idle can be plugs, coils, ESS, MAF, injectors, neutral switch, clutch switch, vacuum leaks, compression, OMP or oil line or oil injector failure and I'm sure there are more.

You are working your way down the list so stay systematic and patiently research and test each possibility until it is solved.
Then we can call you a guru... at least for idle issues

Sorry I didn't reply sooner, didn't get email reply notifications.

You've just described my car, it acts pretty much like this, but not quite that bad. Idle is usually ok when it's cool, but once it's hot it runs from 800 to 1100 or so, lower when the AC kicks on. Shudders a lot, but I think that's probably a separate issue from the low idle.

I had my motor mounts replaced about a year and a half ago when I got the car, so that's probably not the problem for me. Is the neutral position/safety switch the same thing on auto and manual transmission vehicles? I'm not getting a CEL for it (no codes at all since I replaced the downstream O2 sensor), but it certainly has trouble keeping a reasonable idle when it's hot.

Any way to test that switch?

I edited the sound on the video to remove the rumble and hiss so it's easier to hear this noise.

Logged STFT and MAF today. At cold idle it ranges from -3 to +2.3, with MAF at ~6.3.

Driving, it ranges mostly +/-5 (tends to be more negative than positive), but regularly hits -10, and reaches -20 at a couple of points.

Coincidentally, it stalled at a stoplight today while I was logging.

P0300 this morning. Thinking it might be from when the car stalled yesterday.

I'm coming up on 2 years on this set of plugs though, about 8k miles, suspect it's getting close to time to replace them. That may be contributing to the issues I'm having.

Funny.... I don't recall YOU telling me anything...

I'll be the bigger man here and just ignore the above response.



Yep....that's the noise! Frustrating trying to find the cause of it.

So, today I had a look at my Cat...pics below.

Attachment 187263
Attachment 187264

Cat internals looked fine, nothing loose in the element. It appears as though it is not the problem.

Attachment 187265

This on the other hand...Im not so sure. Of course, this is the O2 before the cat....a little bit of build-up there.

Also, cleaned the crap out of my ESS again, re-checked the plugs.

Guess its back to the drawing board.:dunno:

Well, I solved the problem with mine. Traded in on a new car (Nissan Versa, mostly for the kids). I think I'll wait around a bit for the 2010 and 2011 RX-8s to get a bit cheaper, then get one of those, but manual this time :D

so have you come up with anything i also have the same issues with my 2004 mazda rx8 AT and have a handfull of things i did to try to solve the problem but still nothing i have noticed if i put it in nuetral and hold the brake and gas it seems to idle a lot better but i only did that once so i could make it home and not get stuck on a busy intersection also ran the crap out of it but all it did was pop at high rpm shifts