Hi! one question, this rpm is a engine rpm? or other rpm?
shift_2_3.png
Hi! one question, this rpm is a engine rpm? or other rpm?
shift_2_3.png
Last edited by Luis1grfe; 03-06-2020 at 09:30 PM.
Shift scheduling is based on output shaft RPMOriginally Posted by Luis1grfe
Hi SlowNStock, thanks for your feedback. How to calc engine rpm in based to output shaft RPM? I read information in internet but I dont understand.
Regards and thanks very much.
Here's what I use for the Tacoma transmissions. I think you'll find the modified values in this spreadsheet quite enjoyable, but feel free to tweak as you see fit.Shift Helper v12.xlsx
Thanks very much!
Regards
Luis
Hey @JustDSM, do you have the same spreadsheet for 6 shifts Tundra ?
would you shed light on how to use the spreadsheet? Tundra Gear ration is 4.3
The one I use is in this post: https://forum.hptuners.com/showthrea...l=1#post598929
Super old thread... But I have a bit of a hard time understanding the downshift. If I put a bigger rpm at a set TPS, will it downshift more eagerly or will I need to press the accelerator MORE to get it to downshift.
For example, I would like to avoid the 2-1 downshift most of the time and be able to go almost WOT without it downshifting except when going super slow.
If you increase Output Shaft RPM for a given Throttle Angle, it will be more prone to downshifting; this has the same effect as decreasing Throttle Angle for a given Output Shaft RPM.
In general, you're much better served by modifying Throttle Angle for a given Output Shaft RPM - it's much more intuitive and it's easier to monitor shifts you may want to change without logging, because you always have the tach and speedometer in your field of view. For example, if we are driving around and notice the truck is downshifting too readily at 2000 RPM (Engine) or 20 MPH, we can figure out the equivalent Output Shaft RPM, then simply increase the Throttle Angle for that downshift.
My recommendation is to modify the Output Shaft RPM values to more reasonable numbers, then you can easily work in terms of Throttle Angle, increasing if it downshifts too readily, and decreasing if it holds a gear too long (and vice versa for upshifts: decreasing if it upshifts too readily, increasing if it holds a gear too long).
Here's a simple tool that will help you convert Engine RPM or Vehicle Speed to Output Shaft RPM and translate your current shift schedule using those new values: https://docs.google.com/spreadsheets...it?usp=sharing
Thanks for the very prompt reply. I had already built an excel to translate to speed and engine rpm in each gear.
Didn't think you could change the "scale" of the graph but then I saw right click > column axis > edit.
I kinda had it figured out because after posting I interpolated the stock tables (which the shift and downshift pattern doesn't have the same scaling) and did the difference between the shift point and the downshift point for each gear. A bigger delta number means it will hold the gear more. A smaller delta means it will downshift more eagerly (and maybe hunt). My excel file includes value from nd4spdbh and cjm11083 to compare. The shift pattern strategy isn't exaclty what I want but it's fun to compare. I'll share it later here if there are ok with that.
My new tune is so much better that stock (to me) for daily driving around, came out exactly how I wanted it to.
I still have a bit of flare from 4th to 5th, which my new parameters made less worse and at lower speed than previous.
I've read that increasing the "optimum trans torque" table in this particular range could help. I have a bit of a hard time understanding what it does exactly.
Also surprised finding negative values in the stock table in the area of interest.
Can someone enlighten me ?
OTTS.JPG
That difference between up- and downshift is "shift hysteresis" - very good parameter to use when modifying the shift schedule.
The same concept applies to torque converter lock/unlock and extends to the interaction between converter lock/unlock and up/downshift, too.
What are you terming as "flare"? Do you have a log that captures it?
I ask as a 4-5 shift from a locked converter can give the sensation of flare as the converter unlocks, when there isn't what we'd traditionally think of as flare, mechanically.
The Optimum Torque Trans table has a few functions, which is a lengthier explanation, but the quick, high-level takeaway is the values in the table should be a model of ideal torque for a given throttle angle, or reasonably close - which is why you're seeing negative values (i.e., engine braking).
I'll try to do a log shortly.
By flare I mean less say I'm doing 2200 rpm in 4th, kinda "floating" very low tps (past the normal shift schedule) If I keep the very low tps position, it will kinda hit a neutral to ~2800 then shift. Stock was doing this for 9 years I've owned the truck which I learned to avoid. With the new tune the effect is way less but still there. When it wants to flare, increasing throttle input a very little bit with make the clutch or converter "stick" you can feel the increase pressure building up.
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