Strange idle
 

To start off about the car
06 rx-8 6 speed
41,721
Bone stock other than BHR coils etc.
Changed plugs,wires,coil pack, tranny, rear dif fluids all at 30k miles

Oil is changed every 3k miles
I know people hate it but I use conv. 5w20

When at idle my cars rpm will drop down to the notch below the 1k mark. Im assuming 750? but when it does the whole car will shake... Go back to normal rpm and then it will be fine. It does this several times everytime the car idles. I take good care of the car. It doesn't see the track. It's a daily driver with almost all highway. I rev to 9k once a day or more depending, to clear out the engine once in a while. Does this seem like a big issue or should I blow it off as a temperamental rotary. I've had the car since aug 2009. Done it since day 1. Was hoping after some maintenance it would go away but no luck. Any suggestions?

That usuallly indicates the need for an e-shaft profile reset (20 brake pedal stomp procedure), a MAF sensor cleaning, and/or air filter replacement.
If none of these work, it may be the purge solenoid system.

+1^...Charles knows....come back and let us know how it went...

Sorry forgot to mention I did the air filter with a k&n. I'll have to look into those. Thanks for the quick response. Gotta love bhr =]

I have made the mistake in the past of overestimating how much oil was needed on the K+N. Maybe your MAF is loaded?

I'll throw in one other outside shot possibility if the standard stuff Charles offered doesn't result in a fix - a failing motor mount.

Please enlighten me, why would the motor mount effect rpm....?

clean the MAF

inspect motor mounts... we do this because as the car "hunts" for idle the RPM will jump up and down. If you have a failing motor mount while your idle is hunting then you would result in a very rough idle when it dips under 1k

Op didn't mention about vibration during idle, only unstable rpm...
If the motor mount goes out, the car would have vibrates no mater what rpm is during idle.

He kind of did mention the whole car shaking when the idle hunts though.

Ok. Just took the Maf out and sprayed the heck out of it with Maf cleaner. Waiting on it to fully dry before I put it back in. Not familiar with shaft reset? Jus turn the car on and hit the brakes 20 times I'm assuming? Anything special? I'm on my phone at work. Kinda hard to search lol

Ignore my last post. Just put it back in and I'm assuming I did the e shaft reset just fine. My oil pressure gauge bounced up and back down. Turned the car on and what a difference. Car was idling at 1100 till it warmed up then sat right at like 850ish. No bouncing at app. My car was idling at 3k till it warmed up before. I just assumed this was normal for rotaries (my 1st if you hadn't guessed). But thanks everyone for the help. No rough idle. Shifter vibrates less. Car sounds better. Car doesn't shake anymore from what I can tell.

The idle is slowly re-appearing. It's not as noticae but it is still a slight drop in rpm and the car is startingto shake a little again. Defiantly not as bad as before cleaning the Maf and the e shaft reset.... Any other ideas? Think it might be the motor mounts or a compression issue? Taking shots in the dark here.....

Could be compression, could be a bunch of other things. Your signature bar doesn't say where your from - where do you drive the car? What was the outside ambient temperature when it seemed like the idle was starting to stumble again? Any chance that the AC was on at that time? Assume your not seeing issues other than idle, but just to ask, have you run the vehicle under heavy load & high RPM conditions lately (say something like going up a steep hill in a lower gear with wide open throttle and high revs on the tach) to see if your feeling the car misfire at all?

sorry, I live in Virginia Beach, VA. No hills in the area.... we are sea level everywhere lol.... literally. I do rev to 9kish on a consistent basis WOT. i think i mentioned that earlier but i dont feel a misfire at all. Outside temp has been a consistent 80 give or take. I dont remember if the AC was on... its nice out i dont remember if i had the windows up or down.... didnt think that would have made a difference

where abouts in virginia beach are you i live here as well and i have the same problem with my car especially when the fans kick on the car appears to drop in rpm and start to shake but once the rpm is above 900 theres no shake at all and everything runs smoothly i've always wondered if it was common in other rx8's as well

I live near damn neck base. Yeah I'm still having the issue. It went away for a short while after the e shaft reset but it was short lived. Any one else have this issue or a long term fix?

Where might this purge solenoid be? I'm having issues like the OP and i've already tried all the usual fixes. I'd like to hear more about this solenoid!

-Lawrence

i'm between laskin and virginia beach blvd what is this solenoid everyone keeps talking about like what does it do i'm not very good when it comes to engines

Look for a vacuum leak, spray your maf cleaner over the various tubes and sensors, see if the idle changes when you hit a leak.

Check the little vacuum line right under/behind the throttle body, a common leak.

So I unplugged the electrical connector to the evap purge solenoid and masked the check engine light with my AccessPort. The car does not seem to do the occasional shudder at idle anymore. The question then is for people who don't have APs, how do they clean/repair? the evap purge solenoid?

-Lawrence

That's a great question. If an ap is all I need it may just top my list of things to buy right now.

I have the exact same problem with my 8. I changed the air filter, and cleaned the MAF sensor, after cleaning it, the idle wouldn't drop below 1000 anymore, but after a couple days the problem came back. My guess was it is a bad MAF because once it was cleaned it worked. I don't know if they slowly go bad like that, but since they're expensive I wanted to make sure of the problem before replacing parts.

It also "hunts" at around 750 or 800 RPM, starts to shake like it's going to die, then jumps up to around a 1000 for a few seconds...then makes it's way back down.

bump it back up!!

im also having this problem. i'll pull up to a red light and the entire fricken car will rumble and shake for a few seconds then stop for a few seconds and just repeat this process. Completely goes away once i start driving. my shifter also shakes a lot when this happens. its becoming rather scary and kinda funny when i have passengers that arent expecting it =P

i'll go home after work today to try the maf cleaning and pumping the breaks trick. is there anything else on this in terms of fixing it? does mazda have any say on the matter?

Myterial, did you find a solution?

Mods: ap dual res midpipe, exedy stage1 clutch kit, k&n typhoon2
2004 6spd 89k miles

No I havnt found a solution yet. 1 person says they fixed it with their ap but I don't have one so I'm boned their. I havnt found any vacuum leaks either. I'm out of ideas and by how many people say the exact same thing ad me, it's got to be a common issue. My shifter vibrates like crazy at idle and is perfect while driving just like your. Wish someone had an idea of what to do.