I've got a 2012 Max Premium with about 24,000 miles on it. About 3 months ago I started noticing a bit of rough idle when stopped but in drive. Doesn't do it if it's running in park. Kind of comes and goes as I'm sitting at a light. I don't notice any real movement on the tach as it comes and goes.

I have only used 93 octane, usually from Shell. I tried a couple of tanks of Mobil but didn't notice any change. The last time it was in for oil I had the dealer check it. They said they found some crud on the throttle body assembly, cleaned that up and "relearned the idle setting" which I assume is a programing process. It did seem better for a week or two but now it's back. Otherwise the car seems to run fine. Any thoughts or suggestions would be appreciated.

 

Not likely with this little amount of mileage but maybe you need a fuel injector cleaning.

 

Cars these days don't need fuel injector cleaning. Between the design of the fuel injectors and the detergent in all fuel, it is no longer an issue.

My 2011 idles a it rough at times as well, but then I look at the tach and see it is idling at about 600 RPM, so it makes sense. I don't like it, but I am not worried about it.

 

perhaps when the engine controller sets the parameters for burning the gasoline residues that build up in the EVAP canister you are getting the slightly rough idle. Or the alternator is requesting more juice from the drive belt to charge that POS OEM battery )

 

Check your avg milage and see if it starts to drop.

Mine does the exact same thing. I have about 34k and use M1 oil and have a Drop-in K&N filter and use Shell Premium only.
I first cleaned my throttle body which I first suspected; it was dirty but I still had the same roughness.
I then tried the Royal Purple Fuel injecting cleaner. That didn't help either.
One thing I notice is my milage avg is about 14 per gl via mixed some short frwy and mostly street. Knew the milage was going to be low but didnt think this low. Wonder if the rough idle is causing this or it's just the traffic conditions on the road.
I'm thinking of taking it in soon. I'll pay as long as they fix the problem if it is a problem.
My wifes 13 year old SUV runs smoother than mine after it was all tuned up. What the hell!

 

There is always a remote possibility that you have a bad motor mount, but your car is pretty new so that's not a real strong possibility. If it is bugging you, your car is still under warranty, so you might consider mentioning it at the stealership and see if they'll poke around.

 

I would disconnect your negative overnight and reconnect. See what happens. Usually if it was a seasonal change or driving habits then it should resolve itself. Sensors are very fickle these days with a high margin of PCM correction. It seems like your playing roulette getting a new car because you never know which sensor manufacturer you will end up with.

Anyway, give it a whirl you may just surprise yourself...

 

On latest trip to dealer they replaced the engine control module and performed an engine idle check/ adjustment. So far it seems to have done the trick.

 

Thats good to hear. Was that a warranty repair or did you pay out of pocket? If so how much was it to fix?

 

No charge from the dealer.

 

That's good to hear. Not every dealer is like that.

 

Let me guess, Toyota or Lexus?