I have about 2500 miles now on my 2013 4Runner, and have been noticing a mildly rough idle at times, mostly when in P or N. It doesn't happen every time, and it can happen whether my AC is on or off. But it pretty much always happens when my foot is on the brake.

It normally happens when I am stopped in a parking space, or in my garage and idling in Park, with my foot on the brake. If take my foot off the brake, sometimes it will go away. Also, if turn the AC on or Off (Depending whether it is on or off) it will go away. It doesn't happen at all during normal driving, except for maybe 1 in 4 times when I am stopped at a stoplight in D, with my foot on the brake, but it happens way more frequently when I am in Park, as described above.

I have heard from some people that it is somewhat normal for this engine to idle rough, and others say theirs don't idle rough at all.

I am almost wondering if that this is normal, and what I am experiencing is the idle adjusting to deal with the changing load on the engine, like the AC compressor going on and off. Also, I believe these have electronic brake boosters, and maybe that is putting load on the electrical system, causing the idle to increase to a frequency that resonates, and that is what is causing the light vibration (Which is why it always happens when my foot is on the brake).

I have also heard that the 1GR-FE idles very lean, and that can cause some vibration. What do you guys think?

I would bet its emissions related. Like if an EGR valve is open.

But I'm not super familiar with this 4.0, but that sounds like typical emissions stuff.

Wouldn't something like that throw a code? I do have Techstream, and haven't seen any codes.

I am guessing yours doesn't have this rough idle?

Just a suggestion: vacuum line. If this has been doing this from the beginning this could be a possibility.

Is the idle really rough as in it feels like the engine is about to stumble, or are we talking about a mild vibration you need to concentrate on to notice?

I haven't really noticed any strange vibrations as you have described, but I am also not really paying much attention to it. The way I see it is, it's a spinning engine with tons of variable constantly changing around it, there's bound to be a minor hiccup here and there when the ECM is trying to steady the idle. Personally, I wouldn't loose too much sleep over it.

Of course I'm just speculating, but I think what you are describing is likely normal with so few miles on the vehicle. If anything was seriously wrong, these super advance ECMs would likely catch it and throw some kind of check engine light your way

It is more of a mild vibration. The kind of vibration you would normally feel when turning on AC in an older car (Say one with 100k+ miles on it). It is just the AC isn't always the cause of it, and it is a new car. I don't think the average person would notice it, but I am very sensitive to things like that. I have a feeling that it is just a normal characteristic of this engine, I just wanted to hear a few other's feedback on this.

I would guess if it was anything to worry about, I would see some kind of code/engine light.

badhabits, would a vacuum leak give me an error code?

No unless it directly affected another system that could produce a code.

I'm not saying anything is wrong, just a reason for the vibration.

My old mustang had a B303 cam, that's a vibration!

Willy,
I wonder if it has something to do with that silly air pump on the 2013's...
Also, you have not mentioned what octane fuel you are running.

My 2012 with a little over 3000mi, running "plus" (89 octane), purrs likes a kitten.

My 13 SR5 runs smoothly that is why I think that something easy to overlook that is causing the problem. At 2500 miles it is unlikely to be filters or anything similar. I wonder if you got some bad gas with water in it.

It very well could be that AIP, but from my understanding, it is only in use when the car is cold, at it just helps the car and cats get you up to temp, then it doesn't do anything once you are at temp. However I am not 100% sure if that is true, because I can hear something I believe to be the AIP when I am accelerating under med-heavy load...Unless that noise is a Vacuum leak...

I have just been running 87 Octane, Shell or Cheveron. Also, my 4nr is completely stock. Also, it has happened for several tanks now, and I have been using different brands and stations, so I don't think it would be gas contamination. Too bad I can't easily access my spark plugs to take a look at them....

On a side note, I hear our engines come with 3 NGKs on one side, and 3 Densos on the other side, and replacing the NGKs with Densos improves response and idle....

where did you hear that, exactly?

It was on the FJ Forum...It was on a 2009 and a FJ, but it is the same engine as ours. So I wouldn't bet my life on it, but it may be the same for the 1GR-FE in our 4runners.

ah, no, i don't think so. the 2010+ 4Runners have the updated, dual VVTi, roller-rocker 1GR-FE.

On my way home last night, I did some testing, and I can reproduce the rough idle now every time.

Basically what I am seeing is when my engine's RPMs are around 750 RPM (I will find the exact number later with techstream) I notice a moderately rough stumble/rugh idle that I can feel through the brake pedal, steering wheel, and seat.

When my car is up to temp, and I come to a stop, say at a stop light. my idle is approx 550RPM in D. At this RPM it is very smooth, and there is no issue. While stopped, if I shift into N or P, the RPMs jump up to about 800RPM. At 800RPM it is smooth as well. Then after a few sec, the idle will settle down to about 750RPM. It is at this RPM where I notice the rough idle. The weird thing is that the Idle will fluctuate about 100 rpm, between say 750 and 850. When ever it gets around 750 it will be rough, then it will start increasing, and be smooth again.

If I do anything to change the load on the engine, the idle will adjust and become smooth. If I crank the steering wheel, the idle will increase from 750, and it will be smooth, for a few sec, the settle back down to 750 and be rough. If I turn on the AC, the Idle will increase, and be out of the "Rough Range".

I am going to reproduce this with Tech Stream and get exact numbers. I feel that there is just some natural resonance with my engine at about 750rpms that causes this rough idle. Most of the time I will never experience this, because if I keep it in D, and idle, the 550rpm idle is smooth.

Does anyone else want to test this out and let me know if their idle is rough in N at about 750rpms? Or maybe this is just an imbalance in my engine. I am also surprised to see how much my RPM needle moves around, when stopped at idle. Is that normal for these engines? I haven't experienced this in any of my other vehicles.