I have noticed this on my mine as well. It's only done it a few times.

I'm having an issue with coasting in neutral though. I was going down a hill the other day in neutral and the stick shift started to vibrate(badly)--the engine also made a noise sort of like a lawn mower sound. It immediately stopped when i pushed the clutch in. I haven't had the stick vibrate again but I have heard the "lawn mower" noise a few more times while coasting in neutral. My car has about 300 miles on it.

I've had this same issue on my Celica and it almost never happens regularly, but exactly as you mentioned as either at a stop or approaching a stop. Maybe it's a toyota thing although the motor is mostly subaru on the FRS so I'm not even sure about that one. I'd keep an eye on it since you said its happened 6 times already (I had it happen 6 times over 10 years probably). It could also be bad gas so try switching up brands and see if anything changes. Oh and stay away from any cheapo brand gas stations.

Mine has done the same thing...I am on my first tank of gas after the dealers first tank. I notice it with or without a/c on. I have a manual as well. Not sure which gas station the dealer used for the 1st fill up, but all of my cars use Chevron...Uncle worked for them for 30 years. If we had Exxon I would use them as well. I believe it is normal. I am at 355 miles.

did this to me too, the fact the engine can recover from 400 rpms is pretty impressive lol...

I'm a little concerned with this issue, not quite acceptable to have idle dip or stability issue.. for a direct injection car with modern ECU idle should be rock steady... didn't they test these cars besides thrashing them around the track?

they did, its a part of the calibration i guess, engine trying to figure out how low it can idle without dying i guess :P new engines and ecus are weird...

Well I am glad I'm not the only one with this issue. It may be part of the break-in tho, but the only way we will ever know for sure, is a thousand or so miles after its over. It may even become a recall if so many people are having this issue even after the break in.

More likely it'll become an ECU flash update "campaign" to be done whenever a customer brings their vehicle in for other reasons.

Mine does the same thing only just at start up for a very brief moment after the cold start idle up it states in the owners manual that this sort of behavior is normal during start up. If it bothers you I would have it checked out, a good dealership should be willing to check it out maybe open a tas case could result in a ecu reflash for everyone ; ). Btw it's not uncommon to see multiple tsb updates for ecu reflash for drivability, throttle response, fuel consumption etc .

There is almost no way this is part of a new ECU learning how to idle. This isn't 1986 and electronic fuel injection isn't exactly rocket surgery. I also don't think it's a normal part of break-in.

Sounds like there's a hole in the stock tune. Somewhere, probably closed loop, possibly in an independent clutch-in map. I know the GM PCMs would crack the throttle a bit independently if you started to release the clutch and didn't add any gas at all.

:popcorn:

let's start a recall
 

What you are experiencing is not normal, I have started the same thread on another forum. I picked up my car this last week and within about 20-30 miles I started to experience the same problem you are describing except my car actually stalled and the car displayed a check engine light. I took my car to a local toyota dealership and the car stalled in their bay. After restarting the car every light in the dash was illuminated including the check engine light. I have not had the FR-S even one full day, I haven't pushed it beyond any normal means and have only hit 65 MPH. They had to have a scion and toyota rep stop by the shop and now the car has been with them for 2 days and they still don't know what is causing this issue. They are doing a live diagnostic with a rep from California on Monday to determine the ECU fault and possibly correct the problem. If you are still experiencing this issue you should take it to your dealership before further damaging anything in the engine. Ill keep you posted on the outcome.

even with the ac off the unit will still kick in. see if it still happens with the interior fan switched off as that will turn of the ac also. ( i just found this out in my evo as i was having a similar issue.)

Keep us updated ^.