Uh-oh or quirk?
 

While sitting at idle, I sporadically notice what I can only describe as a power train shudder. You feel a slight shake in the seat.

The idle does not stumble, clutch in or out doesn't seem to matter. It seems to get better the longer it's driven.


Is this "normal"?

Background:
-2014 BRZ 6MT
-stock power train
-observed break-in recommendation, car hasn't been abused in any way
-2500km (1600 Murica') on the clock
-91 octane (Canada)
-600rpm constant idle, no tach or auditory change
-car doesn't present as knocking
-no loss in power under acceleration
-happens with/without a/c

Try turning the A/C off and see if it still happens. It could be the compressor just turning on and off. It's a small engine so it takes some grunt to keep the inside cool.

If your AC is on it will jump up and down every min or so. I haven't really noticed it doing it when the AC is off. Although mine is on about 80% of the time

I rarely drive with a/c or HVAC, although a good thought.

It will also turn the A/C on if you have the defroster on causing the shudder.

There's at least one active TSB that you can go to the dealer for and try a reflash, depending on your build date it might be beneficial as it should help the DI injector seal meltdown thing and it is supposed to fix 'idle hunting'

I noticed this in my first car that A/C ever worked on. Most vehicles even if A/C is not on but the defrosters are will kick on the A/C Compressor to get rid of moisture.

Does it happen when your lights are off? Can you make it happen by turning them on?

Mine does weird things similar to what you're describing when I put extra load on the alternator. There have been times when I felt the vibration in the car when I turned on the lights or rolled down the windows. Since everything still works, I haven't bothered to take it in. I grew up with British sports cars, so I'm just happy to have an electrical system that doesn't have anything in it made by Lucas.

Happens with HVAC full off.

Likely dumb question but where could I find build date?

That's what bugs me. Doesn't seem dependent on a specific position or input. The wife also noticed it for the first time last night (I had not told her about it) so at least I'm not crazy.

You can find the build date on the sticker on the inside of the driver side door jamb.

I am going to say that this is normal...my idle moves around a little bit with no HVAC on or anything. And its a new car, so you are hypersensitive (as am I).

I noticed that too when I would out the rear defroster on since it is all electrical current at that point.

Yep. Rear defroster does it also on mine.

It makes me wonder how some of these folks with all the lighting upgrades and high-powered stereos avoid this. If they do.

I have had this happen 1-2 times a year. Ac off. Idle seems fine. Just sitting at the light and for a few seconds I feel a odd shudder.