2021 TRD Off-Road 6MT Stumble / Hesitation / Hitching Under Load

Hi everyone! Long time lurker, first time poster. I’ve been around Tacomas for much of my adult life. My mom bought a 2009 double cab 6MT brand new. Then she upgraded to a 2011 6MT double cab, then a 2017 6MT TRD OR. Now my partner owns a 2021 Cement Gray Double Cab TRD OR 6MT and mom has a lime green 2023 TRD OR 6MT. I’ve worked on all of them and overall they’ve all been great trucks. I’ve never loved the 3.5 V6 but I’m thankful Toyota still sells the manual trans.

All three of the 3rd gen’s have had a very similar drive ability issue that I’ve never been able to solve. As we all know the 3.5 has a very odd power curve and way that it delivers power. I’ve always chalked that up to the Atkinson / Otto cycle switching, but I could be wrong.

However, all three trucks have also had this weird sensation when you try to accelerate under load at a lower RPM, say under 2500 or so. The truck has the power to accelerate and will, but they each always have a very slight hitching or shuddering sensation when you roll into the throttle. None of them have ever thrown a CEL or had misfire codes but have always had what feels like a very slight misfire or hitching. The 2017 was at the dealer a few times early on for it, but Toyota just basically said it was normal and we lived with it, until that truck burnt a valve on cylinder 5 at 115,000 and got traded in. We bought the 2021 with about 30,000 miles and it had it then and still does it now at 63,000. The 2023 also did it from new.

I know there was a TSB for something along these lines on the early 3rd gen’s, but both the 2021 and 2023 should have that calibration already. I’ve always wondered if an aftermarket tune would fix it so I contacted OTT and their response was basically, there must be something wrong with the truck and the tune won’t fix mechanical issues. So I’m hoping someone here has an idea. It’s not the end of the world and we’ve lived with it for years. That said, I’m a Mechanical Engineer by trade and it bugs me since it just doesn’t seem right and makes an otherwise great truck, just a little annoying. Any ideas are appreciated!

 

Without driving the truck myself, I cannot tell you if it is normal or not. You could ask a trusted friend to drive it and give you feedback.

 

Hard to say for sure based solely on words, but I’d say I probably experience the same thing in mine. Mine is very jumpy yet lethargic at the same time when down low and asking it to do much of anything at all. Always been that way no matter what tune I have, stock or not.

I’m in the same boat as you, don’t like 3.5 but glad there is at least a manual still. I need to drive a 4th gen and see if that solves my complaints.

If you’re noticing this on multiple trucks I’d say it’s probably a characteristic of most of them.

 

I think you have to overthink it. Throttle cable is an actually a computer slowing your response down. If I can remember, I’m gonna drive around with the trac off. See if that changes things. But I never even think about that button. I’ve been tuned and still have this weird slug thing going, but now I think I’ve got the throttle figured out, just with a slower pace and up much higher than I would normally. I’m also winding out my lowest gears past 3500 before shifting.

 

Since you are a mechanic engineer, perhaps you could do a deep dive on this phenomenon that many of us have possibly experienced but described subjectively different.

The engine sometimes behaves oddly in low rpm high throttle situations. I cannot give you an objective/quantatative/analytical description of it though. To me it feels like the throttle-by-wire is refusing to acknowledge increased throttle input, presumably to avoid knock.

 

That’s kinda what I’ve always thought. There’s no reason why a V6 should respond the way it does like this, unless intentionally programmed in. No other vehicle I’ve ever driven has been like this.

 

I only run into this when in 4wd doing serious off road, deep snow, drifting in a parking lot, etc. During daily driving I do not encounter it. That’s partly why I skeptical that I am experiencing the same thing as others.

 

Thanks for all of your responses! I’d love to do a deep dive. It would be interesting to try tunes from different companies on the same truck to see how it changes things.

The best way I can possibly describe it is similar to a misfire but not nearly as noticeable. It’s like a very faint misfire. And it happens at low RPM, high load situations. Like say going up a slight hill in 6th at 60 mph. As you roll into the throttle it’s just a slight jerkyness as the truck try’s to accelerate. Like lugging but more noticeable than just normal lugging, and it happens in situations where lugging shouldn’t.

It’s interesting to me to hear that this has been experienced even on tuned trucks. I was hoping a tune would improve the engine.

 

I always thought it was some sort of tss shit, where they didn’t want to give the truck the full power, like it would get away from people.

 

Tune helps but doesn’t stop the bleeding.

 

I have never experienced a misfire of my 2 tacos as I define the term. I define a misfire as a lack or dysfunctional combustion. Knock, failed ignition spark, lack of compression, poor fuel-air mixture, are examples. This engine is a real trooper as far as misfires as are probably most modern engines.

CAVEAT: I have heard some knock prior to killing the engine.

 

To my knowledge I’ve never experienced a true misfire either. At least there have never been any misfires counted by the computer and no codes for misfires. The one exception was when the 2017 had the issue with cylinder 5, but that was an actual issue and it set a CEL.

 

I have the same issue since new on my 18MT. It is an engine stutter when accelerating from lower RPMs. Feels like somewhat of a misfire but it is not. Very annoying. I have wondered of any of the 'tunes' resolve it. But, I am not interested in getting a tune. Def agree with you that the 3.5FKS is the wrong engine for the manual application.

 

Mine has behaved this way as well. It definitely feels like the ECM is holding back the throttle when you're actually trying to give it more, and sometimes it then goes into an oscillation (this has led to a few stalls while off road, and while pulling trailers).
Seems like it's around 1800 or less RPM when tendency for this to happen is greatest.
I've simply learned not to get overly hard on the throttle unless the engine is above 2500 RPM (or downshifting first). Less RPM than that needs progressively gentler throttle application to avoid it.
It seems to me a tune should be able to help with this (I seem to recall Toyota even released an updated throttle mapping because of this issue, but of course it didn't fix it entirely). I'd have to wonder if maybe you didn't explain it clearly enough for them to think it was a mechanical issue, because it certainly isn't.

 

For what is worth, mine also runs this way. I just try to shift at RPMS that mitigate it. Seems like it's intentional to me.

 

It never happen to me of what you talking about. I have OTT tune, it increased throttle sensitivity on my 2023 6 speed manual Tacoma. You try whatever setting you want.

 

On my 2020 I’ve always had this “stumble” at 1800-2000 rpm. Every gear, sometimes worse than others. Annoying but I haven’t found a solution or culprit either. This is at very light throttle applications as well as heavy. And yes if you drive at higher rpms you can avoid it, but no i do not rev to 4K all the time nor do I want to.

 

I have no tune, but I am not experiencing the stumble on my 2023 TRD Pro. It shifts beautifully, but it is definitely geared too high. I have the 2Lo mod, as yet uninstalled for reverse.

 

Pretty accurate description of how my truck has operated since it was new. When it’s really cold out, it’s even worse until the engine warms up. I can’t believe that the development team at Toyota drove the truck like this and just said “that’s probably fine, no one will even notice.”

 

As an engineer, that gave me quite a laugh. The unfortunate truth is that you’re likely right. Not that the development team would want the truck to drive like that, but development and engineering is often pushed around by other departments like accounting and forced to make decisions they wouldn’t otherwise.