I have occasionally had a rough cold start. I suppose I'll run another bottle of HEET through it to see if that helps. I did that a few weeks ago when I unwinterized it.

 

get a bluetooth obdII reader that can scan live data. you can look to see if there are misfires at idle after starting and on what cylinder.

 

Ugh, I have one NIB in my console. Doh!

 

I had a similar thing after I changed air filter. The air box wasn't seated properly all the way. No CEL. Could be something simple as that or crappy gas. Definitely not normal.

 

I too have noticed a small random fluctuation at idle, especially cold idle in RPMs. It sounds and feels like small re-calculations/adjustments of air/fuel ratio from the ECU.

 

It's perfectly normal. It happens with other (gas) cars as well. Especially with V engine layouts.

The car/ECU will most likely throw a CEL if something's wrong. The 2UR-GSE is a 'performance-oriented' engine first, it might not be as refined and smooth as something like the 1UZ.

Generally, the inline-six is smoother and more balanced because of the design (or even some inline-four), if that's something some of you are looking for/expecting. Or get an EV (not being sarcastic at all).

One thing to keep in mind is that we are different. What feels normal or smooth to one of us might not feel the same to someone else.

 

It's always a bit rough when I'm stopped in drive, very noticeable after cold start (by cold, I just mean like 60F) and when fully warmed up its a bit smoother. Its the kind of shake you feel in the seat / chassis, not the steering wheel. And it's mild enough that a mechanic will probably think I'm crazy.

I was thinking my RR Racing AOS had a vacuum leak and it annoyed me enough to plug in a scan tool, but there's no codes, no misfires and fuel trims look normal. So I guess it's normal, just a little annoying because my IS250 is much smoother even though it's famous for having a rough idle.