RPM fluctuation.....

[WTF]

Mine has done this.. regularly misfires at traffic lights, and twice so far (in 1100kms), it has NEARLY stalled, the car shook and then the revs jumped back up..

:S

[eriktherod]

Now that I have my ScanGauge hooked up, I am hoping to at least get some additional information about it. I suspect it is 100% normal and every FRS/BRZ does it (or can do it).

deucethemoose mentioned MAP tuning being suspect and I think that's a good starting point. My Si did similar (though less often but more drastic) after having it tuned via MAP instead of MAF.

It's been rather warm here and I think when the intake air temp (IAT) gets warmer, it starts to do this to compensate for less air being brought in. Unfortunately, I don't think it's going to get cooler here any time soon so maybe the guys out with colder climates can chime in? My typical IAT temps seem to be a good 10-20 degrees warmer than ambient air, and are in the 100-120*F. Guess there's a good bit of heat soak in the intake system. :/

Adding to the theory, being idle typically means you are stationary. That would mean air flow is less and heat soak becomes more of an issue (higher IAT) because lack of cooling via air flow in the engine bay. I would also believe that lack of air flow to the front of the car (being stationary) would also make less air pressure in the intake system. All of these factors I believe lead to the ECU trying to correct fuel trims, thus this little blip.

One interesting idea would be seeing if it does it while coasting in neutral (perhaps at various speeds like 10-20-30mph). In theory, keeping it in neutral should avoid deceleration fuel cutoff (DFCO). Typically when you see the 127 instantaneous MPG, that means your injectors are not spraying at all, so it may be possible to test.

[NickFRS]

So at work today the dealership called me. They were pleased to inform me that Toyota is aware of the crickets. They say it's abnormal. Toyota is also aware of the engine fluctuation and is taking immediate action on it. They also told me there will most likely be a recall or ecu flash/update. Further more they loved the video I supplied to the dealership and informed me it is actually helping their process. They asked me to have anyone I know with these cars to report to their dealerships about any symptoms you think the car might be having. The sooner we send are cars in the sooner they can fix them! Oh Toyota also told me if the car continues to have fluctuations it might harm the engine. They assume.

-Nick

They are working together on this. Lithuania Subaru said there will be a ecu reflash within the next six months with updates. They arn't saying anything about recalls to start a scare. But their service manager told me its a possibility. Drove up in my frs and they were more then happy to serve me! Even though we have a scion badge it's the same car and they treat it that way. Just different sales. My Toyota rep also told me most of this info is coming from Subaru.

Was a week ago forgot to post on here as well.

[eriktherod]

If both issues are fixed via reflash, that is interesting. I figured the idle fluctuation could be, but the chirping? I thought that was just a byproduct of the high-pressure fuel pump for the DI system.

Guess time will tell!

[Sideways?]

Mine randomly did this the other day.
Only once and I've only had it since Monday, hence I've not done many miles...
I thought it was just a running in thing but I'll definitely keep an eye on it now it appears to be a more widespread "issue"...

Video is good :-)

[b_massey02]

Mine does this randomly too, I put some ethanol fuel conditioner in and it has seemed to get better. Perhaps ethanol related problem? E-10 is pretty much all there is here.

[Skye]

My idle rpm 600 except after start, when idle can suddenly fall to 400. Much quicker fall than my other Subies

[empower-auto]

After installing a lighter crank pulley (Perrin) my fluctuation went away

[OldSkool86]

Originally Posted by empower-auto

After installing a lighter crank pulley (Perrin) my fluctuation went away

Are you 100% positive?

[empower-auto]

Originally Posted by OldSkool86

Are you 100% positive?

Still going strong. Fluctuation hasn't returned.

[Roach]

My RS started doing this after I installed a light-weight flywheel. Although it will only do it once, usually right after warm up. It sounds like this problem is related to the engine not being able to react properly to a certain amount of centrifugal mass.

[WTF]

here is a video of mine dipping to the point the car shudders and nearly stalls

[ame="http://www.youtube.com/watch?v=P5Bir7gBFTc"]Toyota 86 scion fr-s idle issue misfire - YouTube[/ame]

[Bonburner]

Just found this in the BRZ Service Shop Manual -
Idle speed at Park or
Neutral position
MT rpm 650+/-100
AT rpm 700+/-100

Obviously 400 dip is too low.

[ROBOSTIG]

~BUMP~

Any news on this issue?