AC0KG

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?

muncheyboy

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.

zoomman

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.

AC0KG

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

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.

zoomman

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.

muncheyboy

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.

AC0KG

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.

ShinkaEvo

iTrader: (3)

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

AC0KG

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?

Bladecutter

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.

muncheyboy

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.

AC0KG

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

Maybe it has the older ECU firmware?

Easy_E1

iTrader: (2)

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.

AC0KG

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.

AC0KG

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.

PeteInLongBeach

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.

Bladecutter

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.

AC0KG

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.

zoomman

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.

AC0KG

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.

AC0KG

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

AC0KG

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

AC0KG

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.

bse50

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.

AC0KG

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.