My car has a rough idle that can also be heard from the exhaust. If you walk to the back of the car when its idling and you listen to the exhaust you can hear strange "coughing" noises, it sounds like its pumping out air bubbles but not in any particular rythm. Its just sputtering. The car also stutters when rolling at about 30km/h on 2nd gear at about 2500-3000 rpm, not sure if thats normal. If your interested the maintenance and my dealership experiance is as fallows:

I had this problem many months ago and when i got a CEL i went to the dealer ship to check it out. I told them about the problem and they said they would check it out. After checking the car they said that they found the Catylitic Converter was fried and it needed a new one, luckily it was still under warranty.

After fixing that the problem was still there. The car experiance really rough idles and had strange vibrations coming from the engine, so i took it to the dealership again. When i asked them about it they gave me some warnings about, "If we dont find anything wrong with your car your going to have to pay for the inspection." I was determined to make it go away so i let them check it out. It turned out i had a broken engine bracket mount, luckily that was under warranty too.

However, the problem still persisted. I talked to many of the RX8 Club members in person about the problem and most of them said it was my spark plugs or maybe a dirty filter. I want to take it to the dealer and get the spark plugs swapped before winter if its under warranty, but i hear that if the dealer thinks the car is still "safe" to drive they wont fix it and i will have to pay the inspeciton costs or the cost of new spark plugs.

Any ideas? Thanks in advance!

 

An air leak can do that, check the little black nipple immediately behind/under the throttle body - make sure the hose is on tight and the other end isn't pulled off.

S

 

Thanks for the quick reply, I'll check it out. Im just going to make sure all the hoses are tight, since I dont know too much about the workings of these critical components.

 

Darklight9, how come you never bring this up at any of our parking lot meets? This is the first time I heard you mention it.

 

Lol, im too intrigued by everyones endless conversations. I did talk to some people about it and they told me to change the spark plugs at the dealer for free under warranty but, easier said then done.

 

Where do you live ?

 

Woodbine and 16th. Why?

 

how many miles? i'm going to go with the classic of coils wires and plugs

my car was missing at idle and sounded like a cam'd v8 and the above has solved it everytime

 

+1 great place to start

 

My 8 does something similar when idling... small popping noise coming from the exhaust... I spoke to some members on this forum and I was told that was normal....now I'm not sure....Anyone willing to meet up and help me check it out to see what it could be? Much appreciated for any thoughts....
________
ANIME XXX

 

I had the same issue for a long time. Problem went away when I put in the BHR coils. Pull your plugs out, if they're still good then it's likely time for coils.

 

My car has 70k on it and i bought it used so i dont know if the previous owner ever changed his plugs.

As for TheWulfs suggestion, i dont know how to pull the plugs out >.< Im asking here first because i dont want to have to take it to the dealer and let them pull out the plugs, say theres nothing wrong with it, and then charge me for labour.

 

Did they tell you what the codes were when they checked them? My car throws "Random Misfire" when the coils started to go out.

Anyway, at 70K now (how many were on it when you got it?) I would say you are certainly due for coils and plugs.

My car is at 58K, and I just put in my 3rd set of coils. (Essentially 1 set every 3 years.)

There are plenty of DIY threads, but, the easiest way to check the plugs is pull the drivers side wheel off and go in through the wheel well. (If you are nimble, you can go in the top or bottom, but it will take longer.)

 

Spark Plugs:
https://www.rx8club.com/series-i-do-yourself-forum-73/diy-spark-plug-change-145045/


Coils:
https://www.rx8club.com/series-i-do-yourself-forum-73/diy-mazda-ignition-coils-pics-178515/

In my opinion (I'm sure others will disagree) but you want to consider these a regular maintenance item. I seem to do them every 30,000km so far. You might as well do them both together. (Similar lives, and that way you know they are both always good.) Or, look into one of the coil upgrade options, but still do those plugs often. (I've seen some RX7 guys do them yearly.)

 

I believe if the car has 70,000km on it and you dont know if plugs and or coils have been changed now is the time to do so. Other than the sound you havent said if there is a drivability issue.

 

Dealership ain't gonna swap your plugs out under warranty, it's like trying to get new brakes under warranty, ... not gonna happen.

 

Mine does that too. It is a lot better since installing new ignition coils. The old ones were all white and burnt on the bottom.

I have a new set of spark plugs, so hopefully that will make the rough idle go away completely. I didn't want to install both at the same time because then I wouldn't know which swap solved the problem. My inner scientist is always at work even when I am not in the lab.

 

Thats not true cause my friend took his car to the dealership and the parts guy signed him the new plugs. I dont remember which Mazda he went to, maybe it was agincourt of something.

As for any driveablity issues, im not sure since i bought the car less than a year ago. I dont know if its me getting used to the car or the car getting slower. Could be the grip on my tires or the plugs, but what ever it is the car doesnt seem to produce as much power as it used to. Maybe I should get someone else with an 8 to drive my car and tell me if they feel any difference.

Also, my car has trouble starting sometimes, which makes me think its definetly the plugs. Its starting to get worse now, probably because its getting cold.

 

I've just started experiencing the same problem. I changed my plugs, wires, and coils last month. Seafoamed at the same time. I'm about to take mine to the stealership, is the cat covered by the emission system warranty of 100K or the 36K bumper to bumper? I'm on 63K now.

 

the cat is covered under the emissions warranty which is good to 130km

 

okay.. one last thing to mention here. As most folks have mentioned, it's most likely the sparks or coils, however there's one last thing to look at... and that's the wires. An issue such as this could be (and was for me at one point) just a bad connection between the wire and the sparkplug. Unfortunately the connector for the plugs / wires sometimes slide off (one of mine was completely disconnected), so try to verify that they are on there securely (remove and put back on.. make sure you feel a light snap as they go into place).

I'd still recommend you change your plugs / coils at this point anyways...

 

Thanks for all the help everyone. I'll take my car to the dealership to get it looked at since just noticed i'm due for service at 73k and im a little over 71k. I hope its to change my transmission fluid or something cause my shift sometimes feels "bumpy" inside, iunno. Im new to manual transmission so there are so im not sure if thats normal.

So many questions, so little time.