klanham08

Just recently my Automatic 04 8 has been idleing very rough once I come to a stop. It does not happen at every stop, and it only lasts for a few seconds, but it is bothering/worrying me. I am worried that it will only get worse.

Could anyone pinpoint (as best as possible) what is could be that is making my car have a rough idle?

The only thing I can think of is that I have yet to get my 35,000 mile service yet...could that be it?

2SeeKU

iTrader: (1)

Probably the mounts. My 04 Auto does this every now and then, and it has the original mounts.

klanham08

So are the mounts just getting worn down? It just started doing it over the last few days, it has never done it before but maybe once or twice...

Mr.We$t

iTrader: (1)

Can I ask, does this only happen in park and drive!!

klanham08

It rarely happens in park, only when I am on the brake at a stop light or something along those lines.

rodjonathan

iTrader: (6)

this recently happened with me too but i think maybe mine is coz i had the battery out for a few days and i feel/think maybe the fuel trims arent adapted yet ... but its really bad possibly motor mounts too ...

Mr.We$t

iTrader: (1)

A I would agree with the mounts I'm going through this issue but mine is In idle and when I'm in park and I put it in drive and vice versa!!

volcomx31

iTrader: (4)

my AT idles rough/shakes on R,D,M and when you change gears. probably some new mounts will fix the issue.

edblor

I've had the mounts replaced previously, so that is not my issue.

However, mine is in the shop right not for VERY rough idling (even stalls), and it bogs down something fierce at all speeds in all gears. It became undriveable yesterday.

The shop says tentatively it is possibly a vacuum line, and/or idle control, or worse.

We'll see I guess.

If yours gets worse and interferes with driving, take it in!

bhop

Engine mounts can be the main issue but you say that you have a rough idle, so does the RPM dip down when it vibrates? Try getting your coils/spark plugs changed as well. I have had my engine mounts replaced and the car drove a bit better and did not vibrate at all but the idle was still kind of rough and would cause a almost violent tremble/vibration and I got the MAF cleaned and changed the coils/sparkplugs and it went away. You can also have the dealership or mechanic shop hook your car up to a diagnostic machine (I think) and find what exactly is wrong and should cut to the chase fairly easy that way.

klanham08

Yeah when I come to a stop it will dip below 750 RPM and starts to shake badly and then it will go back up to its usually idleing RPMs.

Old Rotor

If your idle is dropping to 750rpm then your motor mounts are not your only problem. Please give us the history on your car. The service it's had and parts replaced. Type of driving it gets(long commutes, short trip), fuel used(reg or prem), ever flooded, mods installed. Have you ever run any engine de-carbon cleaner to improve compression? Just any thing that you can add.

Bigbacon

iTrader: (4)

look at MAF and your air filter/filter box.

My car was doing this and I looked at these two things. Cleaned out the filter and the box and lightly cleaned the MAF and the violent shaking mostly went away. I still get a small dip in RPMs while idle but no for violent vibration for a few seconds and then back to normal and repeat.

bhop

Oh ok, then you might also have a misfire as well.

-MAF cleaned
-New Coils/Spark plugs
-Vibration through your hands could mean motor mounts lol..... Seriously.

klanham08

I got the car USED at 32,000 miles. Since then I have had the oil changed, gas cap replaced, and I have not done any Mods to the car minus the Racing Beat exhaust on the car that was on when I got it.

As for the type of driving, it is driven daily to and from college, which is about 20 miles each way.

I always use PREMIUM gas.

I have never flooded the car (but I don't know if it was ever flooded before).

I have NEVER ran any de-carbon cleaner to improve compression.

- - - - - - - - - -

Last time I took my car into the Mazda shop they told me that at 37,500 miles it was due for new spark plugs and coils, so I am TRYING to wait until then...I only have 2,000 more miles to go.

Old Rotor

I would add a can of Seafoam or BG44K with a quarter tank of gas and run till it's on "E". If this improves things then plugs and another can will most likely help more. It's not a big deal to put plugs, coils, spark plug wires in($250-$300) and about an hour. Get a buddy and follow the "DIY" on the forum.

klanham08

Is this the thing that blows the white smoke out of the exhaust or am I thinking of something else?

And how does this help with a rough idle?

eguth3

since its been cold mine has been idling rough just when in gear and stopped. It goes away when i accelerate and after a period of time it won't even do it when i'm stopped anymore. is this just the car not liking the cold? i have an 06 AT. 23,500 miles

klanham08

Mine is about the same, but it has always sorta had bad idleing, but now that it is getting colder it is a little worse than before.

eguth3

i just got the car about 6 months back with 13,500 miles on it. it runs smooth and has since i got it. this cold weather just seems to make it shimmer and idles louder when i'm stopped. it was really cool a few days ago and it was like a violent shake when i put it into gear. after just half a block when i stopped again it was not nearly as bad but it still idled louder than when it was warm. Sometimes i wonder if i'm just paranoid because i have heard the stories of the engines going bad at just over 30,000 miles.

klanham08

Well I know that RX8's do not like cold weather. Make sure you let your car warm up before you start to drive it. I haven't had VIOLENT shaking yet, just a little more noticeable than in warm weather. I will probably get it checked out for my 37,000 mile service unless it gets worse before then.

eguth3

That helps..i was wondering how they handled the cold that makes me feel a little better. i always rev at 2500 to 3000 for a period of time and let it idle for 4-5 minutes before i leave the house each day. i know its a process and i just hope i'm going about it the right way to make sure the engine doesn't go out on me.

klanham08

You should be alright as long as you take the right steps to make sure you do now mess up your engine.

eguth3

I talked to a Mazda Tech last night that i know and he said that its really nothing to worry about. Just be sure to make sure the engine is warmed up. I did notice though that it only does it at 7-800 rpm in gear. So if that is what it is for anyone else just be sure to warm it up properly.

klanham08

Mine is the same way. It will drop to around 800-700 rpm (Automatic Transmission) when I am stopped, but it is fine once I begin to move.