Super low idle/problems with Tach driving today

Hey guys. New to the forum and was mostly using it to look into questions and answers that might be applicable to my truck now that I've joined the fraternity. I'm driving a 2016 Tacoma SR5. I've never really paid too much attention to the idle while I'm sitting in traffic but if I had to guess I'd say it usually idles around 900-1000 cold and 600-700 RPMs warm. Today when I was coming back from the beach I just happened to look down and I saw that the RPMs seemed really low for rolling at 40 MPH...like 400-500 RPMs (typically rolling around 1100-1200 RPM). These 2016s have the new 3.5L atkinson cycle engines that have all these fuel efficient features and my truck typically gets 22-23 MPG in the city so at first I didn't think it was a huge deal, I figured I was just in 5th or 6th gear. But then I pull up to a red light and look down and the tach is barely floating above 0 RPM. I turned off my radio and listened and could still hear it running. Rev it up a couple times and no change. So I stop in at a Publix and sit and listen to it and nothing seems out of the ordinary. I come back 15 minutes later after grabbing some stuff, fire it up and look at tach. It reads 900 RPM on startup and quickly settles in around 700 RPM. So I start driving around again and get it up around 40 again and everything seems okay again (RPM back around 1200 where I would expect it to be). So it seems like maybe the tach was the issue because I didn't hear a difference and the shifts felt clean. I think maybe the tach was reading about 600-800 RPM off of what it should have been. Any advice? I've only got 14,400k miles on the truck so there's still plenty of warranty left but I don't want to waste a trip into Toyota for a one time thing unless you guys think its serious. Appreciate any feedback. Thanks.

 

That is going to be tough because the Techs will not be able to duplicate it. You can give the dealer a call and ask them what they may be able to do before just showing up, but I think your best bet will be to continue driving it and if you notice it acting funny again try to catch it on video with your phone. That way the tech can see it happen vs just your word.
If the engine didn´t start to shake and you never stalled out, then it would probably just be a tach issue. Good luck.

 

As soon as I shut her down I was like, "damn I should have taken a video." Appreciate the advice. Will keep driving and pay closer attention. Thanks man.