How about a "Driveabilty Enhancemet" TSB for the 2GR-FKS?

Thanks man, I have the V6 and I will certainly engage you again

 

yep...that's why if i am going to be driving in traffic like turning right on a red when i get a gap in oncoming traffic i always have ECT on.

 

first off, the flywheel in our trucks weighs 32 lbs. Then the driveshaft also weighs 35, so overall its like the truck has a 67 lb flywheel essentially, you could literally cut that number in half with an aluminum flywheel and driveshaft. It would increase the performance of the truck quite a bit to do so, especially if you combined it with a new final drive gear ratio... then you could really get one of these trucks moving. Oh yeah, another component of the bogging issue is likely the stock clutch slipping too

 

i would think just the regear would get some 'bogging' issues out, as the mechanical advantage of easier to pull gears would do this high revving v6 some favors

 

Man this transmission is already so finicky I'd hate to think how bad a regear might screw with it

 

Totally agree with MOC221 and his 5 Points in the OP.
Been driving MT's for 45+ years, so know how to shift smoothly. But this long Rev hang, my truck inconsistantly shows, is driving me up the wall.

 

I think that most of the problem, is that they are sharing the code between the MT and the AT. With an AT, it really is necessary to ease up on the bottom end in order to keep it from surging -- problem with overpowered vehicles. But with an MT, you need a much more linear and predictable throttle curve.

 

^^ THIS^^

I was thinking that a recalibration of the ETCS-I , if applied to all 2GR-FKS Tacomas, may not play nice with the auto transmission. Heck, Toyota would rather have their nuts pounded flat than do something that would upset the AT again.

I'd bet my ass you're right about common code. Sorry guys, an update for just manuals then!

Frank

 

Another thought I just had about this is related to the pseudo-atkinson cycle implementation. The reality is that it isn't actually atkinson cycle, since atkinson cycle requires a variable displacement. What this actually does, is it uses some valve trickery to alter the mass of the air in the cylinder at the end of the compression cycle. The effect of it is to reduce the throttle sensitivity by varying degrees dependent on the current operating conditions and power demands. This has two effects; reduction of accidental over-throttle situations caused by excessive throttle sensitivity (reduction in fuel consumption), and improved ability to maintain desired power level with a small range of control input (how far you push the throttle pedal.

The other point where fuel efficiency may be slightly improved is in how it can operate at a lower power output with the throttle further opened (less restrictive). So imagine this; if the throttle is open wide on a full blown otto-cycle engine, the air flows in easily and fills the cylinder. If the throttle is half open on that same engine, it takes more energy to generate the relative vacuum to draw fuel in. Now switch over to the pseudo-atkinson engine, wide open throttle in full otto cycle operation, it behaves exactly the same as the otto-cycle engine. Now switch it into pseudo-atkinson mode, throttle wide open, close the intake valves when the piston has pushed HALF of its volume back out into the intake manifold. In this mode of operation, it generates the same power/torque as the otto-cycle engine did with the throttle partially closed, but didn't have to generate as strong of a vacuum to draw the fuel in, thus saving energy and reducing fuel consumption. BUT, this is not done by controlling the throttle position, since the throttle is still wide open! This is done by controlling the intake valves themselves.

The whole system works around the idea of altering the throttle/power relationship. So what that really means, is that the new program would have to be a lot more sophisticated than simply aligning the throttle pedal with the throttle gate in a linear fashion. It would have to deal with the intake valve timing AND throttle position, in an attempt to align the throttle pedal with the expected torque.

I could do this myself if I had architectural documentation about the ECU and access to a crankshaft dynamometer. I would need to use the dynamometer to generate a multi-dimensional mapping between throttle gate position, intake valve timing, engine speed, and torque output. Unfortunately, the ECU is proprietary.

 

You are speaking about reducing pumping losses to increase efficiency, yes?... When you mentioned the throttle valve staying open in that manner I suddenly remembered reading about a similar setup years ago, and I think it may have been in the Prius hybrid.
I agree with you, it most certainly would be more complicated than simply having the throttle valve follow the pedal position in a linear fashion. There is a lot going on in the 2GR-FKS. But I'm still drawn to that timing diagram in the engine PDF - it clearly shows longitudinal Gs being reduced "with control" by: delaying or smoothing throttle valve angle AND ignition timing reaction to input. There may be many other factors at play, but I don't need/want that kind of nanny software trying to give me a "smoother ride". It may or may not be responsible for the five complaints I listed in my original thread - I'd sure as hell like to find out, because the driving experience could be made better IMO.

Thanks for the detailed post BTW, read it three times to let it all sink in!

Hmmm, has anyone noticed that the engine braking is less than you'd expect with this V6? Might be directly related to the Atkinson cycle as described above..

Frank

 

Yes!! The compression sucks compared to my Ranger.

 

Its probably going full pseudo-atkinson when you let off the throttle completely. Basically zero compression.

This would be another source of fuel savings. Essentially, it allows you to coast without (a) compression slowing you down, (b) requiring fuel to maintain.

I know that my 2TR-FE will go into an "injectors off" mode when descending a fairly steep hill, but if the hill isn't steep enough, I need to stay in the throttle to overcome the compression. This would allow you to stay out of the throttle on light downgrades in an injectors off state.

If they did it right, this would be tied into the cruise control in order to adjust the degree of compression braking via intake valve timing on downgrades.

 

I have noticed all of this after 10k since Feb. I've learned to shift at 4k+ sometimes, and I find myself watching yellow lights and goosing the throttle like I'm trying to race people at long left turns to avoid that dangerous 'bogging down'.

I'm wondering if any upgrade to intake (filter, CAI) would help. Saw a youtube video of a dyno test with a CAI https://youtu.be/uPWC_td-j0M . This seems to make higher torque achievable at lower RPM.

Is this something that could help as well?



-Also I'm gonna look into that trans fluid, though I am skiddish to do something while I'm still under powertrain on a first MY w/ new (to Toyota) driveline.

 

I don't care for the random down shifts when letting off pedal... it really makes coasting harder and slows the vehicle prematurely

 

To confirm a little of what you are all talking about, I am coming from a 2015 WRX 6MT. Subaru built in a similair throttle logic to have an "all or Nothing" throttle response, however, it was backwards. Light accelerator operation did indeed get you light throttle actuation, but anything past light was like opening full throttle. I learned to deal with it, and loved it BTW, but the agressive throttle caused engines to blow up (look up low speed pre-ignition for the 2.0 DIT engines). I'm having a similair issue with my 6MT TRDOR V6. If I absolutely floor it, the truck will comply and get going without hesitation, but can, and will spin the tires. If I try to slowly tip in like you should on a daily driver Manual, I get a bog, followed by a surge and rev hang. I will try what is described above to mitigate the issue, but let's hope that if Toyota fixes it, they make a smooth throttle curve and don't cut power in the mid range (Subaru's solution in the WRX). The update from Subaru absolutely killed the fun in my WRX (one of the reasons for switching to the Tacoma).

 

Not sure what relation your statement has to my post that you quoted...?

 

Bump for the new batch of ppl experiencing throttle lag/hesitation..

Frank

 

Subscribing as I have similar issues/concerns with my 6spd auto.

 

Also subscribing because I've been on a quest to figure out what's going on with my 2.7/auto and the graphs in the OP depict what I'm experiencing EXACTLY. So this thread was a fantastic find. The feel of my truck when starting out from a stop, is significantly different than any other auto I've driven. It's not something that's bothersome to me but the torque converter loading throw you back in your seat torque boost off the line is definitely absent whether it be for fuel savings or to prevent wheel spin or both.

 

Frank - excellent analysis. I traded my 2008 for a 2017 and have a similar experience. On my test drive - in retrospect - initial accel was surprisingly weak. After a week with the 2017, I've launched across traffic several times with white knuckles. At 278hp, the new engine is a lot more powerful - it's not that.

My sense is - and the non-dimensional graph confirms it - the program lowers the gain on the pedal, which is what that knuckle in the graph shows, as it carves off the first acceleration peak that gives you a sense of survival. There may also be a latency during sampling or response, hard to say.

Turning off ECT, and truck feels a lot more like the 2008 - more of a 1:1 pedal:throttle connection. It's a really stupid thing to do - change a control response due to some other criteria or relationship. I am pretty sure my truck can't see the oncoming traffic, so they are taking a pretty good computer - the driver - right out of the loop.

Hard to say why they would do this. Toyota makes some stupid engineering calls, mostly along the lines of "just because you can doesn't mean you should". For instance, the ECT switch is no longer "sticky" - they don't trust you to know what you want? My 2008 had a PWM dome-light slow dim that was probably some engineering summer intern's project. But they also used it for "on time". Every evening you jumped in and needed light, you sat through a 5 second slow glow - sometimes I could light my cell phone quicker. I used to dream of finding that Toyota engineer one day and choking the life out of him.

I am already seeing people jumpering circuit boards to change functions, they could have let the user set. Just loaded Entune, and I have to OK it "might use data"...every...fricking...time? I write software, and if I did stuff like this, I couldn't hide. Toyota engineers can, unfortunately. I guess they don't drive these cars, or have better firmware in Japan.

Gregg