Gdubdub

I have the M flash on my car already, but I was wondering if the idle fluctuating from about 750rpm to 1100rpm was normal. When it hits 750, the car kinda shakes a little, not a big deal, I just wonder if this is a normal situation.

I still have not found a cause for my freak overheating (happened once and never again) and I wonder if maybe this could be related. Does anyone that has the M flash have this fluctuating idle as well or should I complain to the dealership???

Thanks in advance!

mysql101

my car idles around 2000 rpm when i start it up.

once it's done with the high idle (around 30-60 secs), it idles at 1000 rpm. When it's fully warm, it idles just a hair under 1k rpm. It doesn't move at all. Not even slightly. It's been this way for the last 2600 miles that I've had it.

Hope that helps.

cgrx

If you don't have any aftermarket mods I'd go get it checked out.
Does this happen when the car is full warmed up ?

Gdubdub

Yes, it pretty much happens all the time, I have always just dismissed this as normal, but have been meaning to ask on this forum. It fluctuates about 5 times a minute when sitting at a stoplight, wether it is cold or warm. I am positive that I have the latest flash, but this is an everyday occurence.

Gdubdub

Any other thoughts or comments? I don't want to go down and complain if this is a normal occurance for most RX8 owners.

Thanks again!

RotorManiac

happened to my previous car, an alfa romeo, it made me nervous, thinking it might die on me, but actually nothing happend all the years i had her. i dunno, maybe its sth with the ecu or battery, but my car kept on going with no prob...

Hard 8

I have the M flash and maybe 8,000 miles on my car. When my engine is warm it seems to idle around 900 or so, but occasionally (like, maybe once a day) it will dip really low for a moment, almost to the point of stalling, then come back again, then dip again, then come back up. Next time I bring it in for service I'll try to remember to mention it.

Just another data point.

Gdubdub

Hard 8, that is exactly what mine does, only it is a fairly constant occurance with me. My dealership just told me to mention it when my AC is fixed (end of the month and it is 105 in AZ, ugh!) but if it is an actual problem, I want to get it back over there quicker. Thanks for the info, keep it coming!

JeRKy 8 Owner

My Rx8 does the vibration thingjust like yours at stop lights and it has doneso for a very long time. My car has over 12000 mileson it and Ive complained about it to dealerships before. They thought Ihad a defective catalytic converter sothey replaced mine at 5000 miles butthe problem came back again a few months later. Im used to it now and dont care enough tolose my car againfor another 2 weeks while another dealership pretends to fix the problem. One service tech told me that rotary engines usuallyhave a slightly rough idle and not to worryabout it. I gave up wastingtime over it andwent w/his theory.

Bythe way I have the M flash installed too. I rememberthat after getting theM flash the rough idle wentaway for a month but ofcourse it eventually came back as always.

Rupes

Mine does that too, shakes like its going to stall, but never does. I wouldn't worry about it untill the day it does stall. They might do more damage trying to fix it.


-Rupes

SpearRX8

There was another thread in which one of the rotary gurus mentioned that this is normal due to the excess unburned fuel passing from one combustion cycle to the next. Mine does the same thing. But this is a new car should not do this. If this is normal for rotaries then I wish Mazda could raise the idle to just a tad below 1K. It seems to run very smoothly at that RPM. I do not know if this can be done due to emissions. MAZDA, ARE U LISTENING....

affenage

I have the fluctuating idle since the M flash, but not before. One caveat - I've been using lower octane fuel (either 89 or 1/2 tank 93 and 1/2 tank 87).
My MT SUV idles rough on lower octane fuels. I also know that regular trips up the tach to redline helps the idle calm down somewhat in the SUV. (maybe my imagination?)

red_rx8_red_int

Mines done this from day one (august 03) and has continued through all reflashes.

azureknight

i think this "pulsating" is normal for rotary engines...isn't it?

Kel Rx8

mines does it
all i have is re intake
but use to it

Meowloud

I posted in a similar thread months ago. There was no answer to be found, but others did have a similar experience.
My MT, no mods, 3k miles on the odo. will idle at 6 - 700 RPMs at a stoplight. After approx. 40 seconds after I've stopped, it will dip to 450 - 500, idle rough, and feel as if it is going to choke.. only for a second, then it 'catches' itself and revs up to ~1k RPMs. Then it will settle back down.
This isn't everyday, but once a week. And it seems to ONLY be at stoplights!! I haven't experienced it at a drive-through, etc.!
I was filling her with 93 octane and just switched to 89 and it seems to idle a bit better (maybe due to flashpoint??)

mysql101

I'm amazed at how many people have this idle problem, and I'm the only one so far saying I don't have it.

I have always used the highest octane available in my car. I have *never* seen my rpm drop below 900. Even if I rev it and let the rpms drop, or sitting at traffic lights. My AC is always on (I'm in FL), and that seems very dependant on engine rpm to function, but thats another story...

RX8_Buckeye

The tach is so damped that you won't always notice idle speed fluctuation just by watching the needle. What really bothers people is the vibration at idle, which is related to idle speed dropping below its normal operating point, then returning to normal speed in a cyclic manner, as well as occasional misfires. It all depends on how sensitive a person is to this sort of thing. To one person, the idle might seem perfectly fine, but to another person it might seem very rough. The same goes for squeaks and rattles.

It's difficult to gauge how prevalent this problem is by polling people on an internet forum. I know my car definitely does this, but it doesn't bother me too much and I'm pretty sure it's not going to harm the vehicle, so I'm not going to worry about it. Here's a link to a similar discussion. Some people had some interesting explanations. In particular, oi812's response about the Renesis's full-time "EGR" function is very insightful.

Why does the renesis "lope" at idle?

MTCD01

I don't have a problem like this either. Pulling up to a light my idle is at 1k and after a few seconds drops to 850-750 ish and stays there for the duration. Pre-M flash I had a very rough popping idle (very rich smelling exhaust), post M it pops occasionally but it has never panted.

Meowloud

F.Y.I. mine has the 'L' reflash.

affenage

I have noticed that mine will defintely idle at higher RPMs if the A/C is on (avg 1200). But the RPMS still fluctuate.

I too, don't think this is anything at all to be concerned with. I haven't yet read the attached thread, but I can say, I've driven plenty of MT vehicles, and they all do it to a certain extent. The renesis, though, seems to be more noticeble than many of the other vehicles I've had.

I am (as of today) switching to 87 octane. Since I really haven't noticed any performance issues at 89 or half and half, it's time to go a notch lower in octane. If I have any noticeable effects other than a rough idle, etc, I'll throw in some 94. But I am not anticipating any problems. (side note to Jason - I've noticed a bigger decrease in performance running the air conditioner than I have dropping the octane of the gas!)

Nubo

I have occasional "bumps" in the idle, very momentary -- never enough to cause the needle to move. RPM seems quite steady. I haven't yet gotten any reflashes. I think my car still has the "K" version. Manufactured in January. Just over 2000 miles.

silver1_rx8

I too have experienced the Idle fluctuation, I called service department on wednesday and they want me to bring it in on Monday to check it out.

AlbertDigital

It happened to me today for the first time. I have a MT with 2200 miles. I was stopped momentarily and the car was warmed up. Idle was at ~1000rpm then it "stalled" for a brief moment just as described in previous posts. It then happened again after about 30 seconds and hasn't happened since. It scared the sh*t out of me! If it does keep occurring I'll give the dealer a call. Hopefully an answer will pop up sooner or later.