Tacoma 2016 - Piston Knocking

2nd Complaint I've got on my "new" truck.

Piston knocking/slapping when the truck accelerates from around 1200RPM @40MPH.

First things First: I'm using 91 to 93 oct Gas since day 1.

It started doing it uphill, since the transmission shifts too soon, sometimes when going uphill the RPM's drop
under 2000. When I step on the pedal to accelerate it . .. Piston knocking right away for a few seconds, then it stops. Whenever the truck goes under the 1200RPM and I need to accelerate again, it knocks. And I'm not confusing this sound with the valve sound (the sewing machine sound) that Toyota still saying that "it's normal". I know what piston knock/slap is and that sound can't be confused. At first I thought I was a casual thing, but it started to doing it even on the Highway.

According to the advantages of an Atkinson Engine: piston knocking is virtually "impossible" or less likely to happen because of the Direct Injection system. When fuel injection happens inside the chamber it is supposed to cool it down to prevent pre-ignition due to overheating. I hope to got this right. Well, if it is not a matter of high temperatures at the combustion chamber, then could it be a too lean air/fuel mixture. And this could explain that hesitation feeling when accelerating/lugging the engine. We know now that there's an under power feeling due to the transmission shifting too soon to higher gears, but this might a stacking issue as well.

Things I found weird....MPG. Frequently this truck is giving me more than 28MPG. That's weird. I mean, or something is f.ckd up, or the MPG calculations are wrong or the ECU just want to save fuel or run the truck with air only ?

I took the truck to the dealer, and guess what ? They didn't find a thing and they've stated that my truck is on spec. I'm taking it back to the dealer again an try to contact Toyota corp. because this is something that needs to be addressed and fixed accordingly.

I'm posting this complaint here because I haven't heard of this before and I really don't know if this is an isolated issue, but the truth is it is not acceptable on a new car.

 

About 97.3% sure 2gr-fks is non interference engine. Havent seen a piston out of one, but doubt they are "high" compression pistons that could even hit valves. Does obviously have vvt, but highly doubt it could get so far off timing it would cause audible metal on metal slamming without setting a over/under advanced timing code

 

Seems quite certain if you read OP

Sorry long day and internet tech drive me silly sometimes. This is one of them. Dont hypothesize, we only have a little to go by, might as well use info provided right?

 

If it's audible in the cabin, try and get a recording of it. Or take the go-pro off the dash and mount it under the hood.

 

take it to the dealer

 

Hi guys,

I forgot to say Hi, I'm new here! This is my first Tacoma, but not the first truck I owned. I've always wanted to buy a Tacoma since I rode a 2001's, but back then i couldn't afford it, not even a compact car.

Anyways I've been reading a lot of threads from different forums and haven't seen anyone reporting a knocking problem, at least not for the 2016 Tacoma. I know about the ECU flash/update for a knocking issue for the 2015 one, a friend of mine were affected by this.

I'm not an expert nor a mechanic, but working with cars since 12yrs, I think I know a couple of things. But with all these modern cars, now it is very difficult to diagnose an issue. Everything is done or monitored by the ECU. I really don't have the time, nor the proper tools to diagnose such a thing, and I have to rely this completely to the dealer. Anyways it is a new car, so if there's warranty, why bother right ? The only thing can do to make sure there is indeed an issue before having to struggle with the dealerhip. I said struggle, because we now that was this is going to be.

But, getting back to the "knocking" issue. At first I thought it was the horrible valve pinging these trucks seems to have (I call it the sewing machine sound) that when you accelerate will scream for your soul, then my dad noticed it, my father and brother in law, and even my wife.

I haven't record a video yet, but I friend just lend me his goPro, so I hope to post it soon. In the meantime the only thing I can do is to narrate the issue:

I'm on the road, just plain flat road no hills. Engine Temp. 1/2 gauge. Coasting at 40MPH and around 1200RPM. As soon as I hit the gas, to let's say accelerate to 60MPH, I can hear the friggin' knocking for couple of seconds then it stops. If I'm going uphill, is the same thing. I first noticed at a hill, but after a few rides I concluded that it is whenever I had to step one the gas, and going from 1200RPMs to let's say 3000.

For now this is all I can tell you guys about the issue. Maybe you can help me out to make sense of it, I mean I know is knocking, but could it be because of a timing issue, too lean mixture, ECU ?
I mean as for the Atkinson engine, it couldn't be pre-ignition due to chamber overheating. At least this is all I can think of.

What do you think ?

BTW, forgive my english, since it is not my primary language.

 

odd that you're getting that much MPG. I'm curious how this knock sound is. It makes it harder to diagnose with out a CEL going off or flashing. You said the knock eventually goes away after accelerating from 1200 RPM or anything under 2000 RPM. If you decelerate under 2k can the knock be heard when it gets under 2K RPM?

 

I've had this happen a couple of times when my truck was younger around 40 mph, hasn't happened in 5,000 miles, just shrugged it off

 

Take it to a Toyota service center

End of story

 

I'm absolutely no gear head, but you mentioned the type of fuel you use. I believe they want us to use 87 fuel. Again no mechanic here, but could that have anything to do with it ?

 

Yeah, I think that's the only thing I could do for now, that and keep you posted.

Trippin, this happens only for a short period of time during acceleration. Im guessing this might be a too lean mixture, why ? This engine has 2 injection systems, Direct port and intake port injectors and the system change back and forward depending speeds. So it might be a problem with this on my truck. That's what Im guessing for now, at least thats what comes to my head.

Anyways, lets see what they tell me on my next visit, which btw is next monday.

 

Thats what the manual says, but at the dealership they've told me to use premium gas. Anyways the higher the octane the smoother your car will run.

 

This is not true.

 

no, the higher the octane, the more money you will spend

 

OP....Post a video.....

 

How cold is your truck when this happens. Is your truck up to temp. I ask this because pistons will knock/slap when they are cold until they get up to temp. then the heat causes them to expand allowing the piston to become larger causing everything to seat. Then the knock/slap should be eliminated.

 

Use regular. The only thing premium does is burn cooler. This is not necessarily a good thing if it's not designed for your engine. Our 3.5 is designed to use regular unleaded. Also try driving with the etc button on. The truck likes to shift into the highest gear and lug around. With the button turned on this is virtually eliminated.

 

Has the motor oil level been verified? Could it be oil starvation? Not sure about the 2GR-FKS and whether it even possible, but low oil level or pressure can cause valve noise.

 

I would run 93 octane (if available) for a few tanks to see if it clears up.

sounds like a classic example of spark knock @ throttle tip in