2016 manual trans V6...intermittent rough idle

So I just bought this thing...100K miles TRDOR, and it has an intermittent very rough idle. I've read about the DI cleaning cycle, but most seem to say that is accompanied by noise. There is no noise in my case, simple what feels like a dead miss. I have not plugged in to check the missfire counter, but since it's not illuminating the CEL, I don't think it's a misfire.

Is this normal on these or should I dig deeper?

 

I would submit that a rough idle, no matter how intermittent is not 'normal'. There are a host of things that could cause this, and it could be more than one. Your best bet for a starting point would be scan tool with live data capability so that you can get a good look at the various engine parameters before and as the issue occurs. If the issue lasts long enough when it occurs, start by disabling each plug/coil in turn. There should be a noticeable drop in engine speed each time this happens; if there's on cylinder where there's no change when you disable the coil, then that's likely your culprit. You then need to determine if it's an ignition or fuel issue. Pull the suspect plug, look for damage to the electrode and boot, as well as carbon 'tracking' (burned areas indicating that the spark has been discharging before the electrode gap. If that's all good, it's likely fuel-related, but could be other things (PCV, EGR... )

 

That's the plan. I'm an ex toyota dealer tech. I have the tooling, just was unclear as to if this was normal due to that cleaning cycle or whatever. This is the newest vehicle I've owned. A lot of new stuff is noisy and shitty compared to...say, a 3.4L that ran like a sewing machine (and actually reacted when the accelerator was depressed...but that's a different topic lol.)

 

Have the plugs been done on this ?

 

I have to assume they're original, and due. I have a new set, along with all the fluids and filters...trying to find time to put it up on the hoist and give it a full service, probably this week.

I just figured that if this wasn't some normal condition, the misfire would have set a P0300-306 by now...and it hasn't.

 

Okay, well, you probably know a lot more about it than I do... strictly shade-tree mechanics here. One issue I did have with an old Chev and intermittent rough running was caused by clogged cats... that was under load though, not at idle. It wasn't a misfire, but it felt like it.

 

Respectfully-
If you’re not sure you have an actual problem (CEL?) or wondering if it’s just the inherit characteristics of this engine:
Why not zoom out and go with the quickest easiest option? Go test drive a couple.

 

I drove a 2021 for a couple days and it didn't do it, but it was an auto. Maybe if I'd have clicked it into neutral waiting a lights I would have felt it? Dunno. I can't find another manual trans or a 2016 (maybe first year issue?...who knows).

Figured I'd ask.

 

I didn’t intend to come off like I was shaming you for asking, I don’t blame ya. I just thought since things we hear and feel are so subjective, a good start would be to test drive and just see if your sensitive to what might be a trait the truck has.

 

My v6 idles smooth like glass, can’t even feel that it’s running unless you really pay attention. If you have rough idle here and there, it’s definitely not normal.

I would start with simple things, like plugs.

 

If it's a hot idle where you see the issue, than that is likely the cleaning cycle. Anything outside of a hot idle and you have some other issue.

 

Cleaning cycle doesn’t cause rough idle though, from my experience anyway.

 

It does on my 18 since day 1. Annoying as fuck and Toyota calls it normal. It is a weird lumpy idle. Goes away as soon as cleaning cycle is done.

 

Hm, strange. I would take a video and show you but I’m in my work van ATM.

Mine just sounds like a diesel when cleaning cycle kicks in.

 

Mine has a rough idle at 75k, what does the idle sound like? Here's mine, hopefully this isn't "bad" sounding:

https://i.imgur.com/OgnOUja.mp4

 

Mine’s the same - I can hear it but not feel it

 

That sounds beautiful, just the cleaning cycle.

 

My v6 purrs. I have a manual transmission, but I have no reason to believe the transmission would have any effect on the idle behavior of the engine.

 

Well like the other poster asked...

THE first thing i would check is the pluges because...

1. they were do for a change around 60K to 70K
2. the plugs have come lose on some people
3. just put plugs in it first before you go deeper.. 45 min to 1-1/2 to change

 

Isn’t it a 100k for plugs?