Tacoma - OVTUNE - VFTUNER - Update Info and Original Development

Cause it had too much power (a 2-stroke 750 I4 stuffed into a modified chassis originally designed for a 4 stroke XT 650/750 twin).

"All slow motorcycles handle well..."

On Topic.....after awhile on 1.04R I'm still fairly happy with it...but the shifting seems to have degraded since the I originally flashed 1.04R....still looking forward to 1.05.

 

Guessing it has something to do with the gears. I just installed 1.04R yesterday after running the TSB for almost 2 months. Previously had 1.03 91. I never had any issues with TSB as it was much smoother and 1.04R has been smooth as well. Not as big of a difference which is a testament to how much better the Toyota TSB is but still feels like the truck is lighter on it's feet with Mat's tune.

 

After spending more time analyzing how toyota does their shift logic on these ECUs, the clunk is from how the downshifts are requested.
I wish I could explain it in easy terms.. it exists in every single version of the AT ECU, including the TSB. It will eventually start happening to any truck over time due to how the shift tables are designed.

It's our aim to fix this completely in 1.05. But I swear to god I don't get why Toyota decided to go the way they did with how they designed HOW the ECU selects gear (up or down).

I've explained it a bit deeper to a few members her privately.

 

It's not a new thing for Toyota....every AT Toyota Pickup I've owned (2003 and 2004 Tacomas and a 2002 Tundra) have had the same downshift to first "thunk". The Tundra was the worst of the lot...till I got the Tacoma.

 

Even so, the Tundra still uses a proper up and down shift schedule. The Tacoma does not..
I don't think people would believe it if I explained how it actually is setup.
What I have learned over the last few months about the transmission explains why it is so difficult to anticipate what is going to happen.

Some good news:
- I've figured out how to totally disable every shift "shuffle"
- I've figured out how to make the truck run on ONE Shift schedule exclusively (which means shifts will always perform the exact same. from mile 1 to mile 50,000). Not condensing the "learning" not condensing the torque tables, but totally disabling entire shift schedules.

The bad news:
- Fine tuning of the transmission shift torque is still required to make the truck shift flawlessly when disabling everything else.

 

3rd Gen. Clunk is new for me, my 2001 & 2011 never had
anything like this after years of ownership.

 

you've mentioned before it's the downshift to 1st gear. Is there anyway to keep it from downshifting to first until the truck comes to a complete stop?

 

Have a look at this (post 59):

https://www.tacomaworld.com/threads/check-engine-light-back-again-x3.566773/page-3#post-18875589

 

It's WAY more prominent in my 3rd Gen. The clunk in my Tundra was fairly noticable...but not to this level. Even the most "mechanically numb" would notice it in a 3rd Gen. The clunk in the older Tacoma's was MUCH milder...I'm sure many people wouldn't notice it at all. I'm am very sensitive to the workings of mechanical things
I spend alot of time around....it's a gift or a curse depending on one's perspective...

 

yes it is possible... but here is the tricky thing. Anything you do to modify the way downshifts are requested...also modifies shifting up. We're working on it.




putting what I edited in on this page:
What I have learned over the last few months about the transmission explains why it is so difficult to anticipate what is going to happen.

Some good news:
- I've figured out how to totally disable every shift "shuffle"
- I've figured out how to make the truck run on ONE Shift schedule exclusively (which means shifts will always perform the exact same. from mile 1 to mile 50,000). Not condensing the "learning" not condensing the torque tables, but totally disabling entire shift schedules.

The bad news:
- Fine tuning of the transmission shift torque is still required to make the truck shift flawlessly when disabling everything else.

 

On TSB/1.04R for almost 3000 miles now and dont' have the 1st gear clunk.

 

I find it amazing just how incredibly complex these systems are...
Thank god for some one like Mat to really take this on and understand it in its totality and make the changes we all desire...
Thanks from a patient customer who's satisfied waiting for you to sort it all out..
Really, thank you..!!

 

the dealership did the tsb.

i could just pull the battery for a bit and see if that clears memory

 

no one else with gears has reported the issue

 

Are the shift algorithms based on vehicle speed or engine speed? Or maybe some type of load calc. What are the inputs to determine when to shift?

 

i did email you and am in no hurry, but will 1.04R fix my redline shifting issue? Will 1.05? or do we need to go custom?

Really, that's my biggest complaint and concern. I worry about highway passing and oops, truck goes full retard and i end up getting in a head on collision because the truck went full stupid.

 

So.. here is what is interesting, and what I was incorrect about when I first started learning how the transmission works...

The shifts are controlled by accelerator angle / requested torque > axle speed > axle speed limit per gear > Table selection > Table selection basis on torque request closest match > Engine Temp (hot,cold) > Gear selected > Transmission Torque value selected > shift (any direction)

This is why the transmission shifts all over the place. Because it does not designate specifically an up or down routine. It only designates limits based on xyz variables.

Here is what will boggle your mind and what we were wrong about in the beginning... The tables do not designate the transmission going up or down. The tables only designate the limit of how a gear can be used.
It's not even that easy to explain.

it's a mess.

This is why 1.05 is taking so long. Now that we understand every critical detail of how the transmission is being used we are rewriting our entire tune (transmission side) to make proper use of this.

 

nm

 

Information coming in hot today. Thanks for the work on this. This just makes 1.05 sound like it is going to be ultimate!

 

I saw improvement in shifting with the new TSB (most of us did and I'm not tuned yet) curious how 1.05 would run with just the TSB and no additional fine tuning to the trans... 1.05R?....I know Mat is hell bent on perfecting 1.05 and glad he is but would assume a 1.05R would still be another step up on 1.04R...just wondering