Hysterisis issue on TPS load gear table

[gboezio]

Hi, I'm polishing my MS3/GPIO install, I have recently tweaked it to drive pretty nicely.
I have recently updated to 4,126 code.
There MAY be another issue regarding the gear shift Hysterisis, it gave me a hard time on code 2,2xx, so I have upgraded to 4,1xx, the issue remains (but I'm not just 100% sure)
I run TPS gear table and MAP PC table, I like a TPS based throttle because it gives control on the trans shift without going full manual

I have the trans Hunting gears sometimes on steady throttle, I have set shift Hyst to 10 km/h and load 10 (units displayed are KPA), but my trans load still follows MAP pressure, I can see on my gear table the dot do follow the TPS load.
So basically my gear table is following TPS and it's shift hysterisis follows the load or MAP signal, but after shifting the MAP increased, but not the throttle, so the tranny could hunt gears from 89,5 to 90,5 km/h, if I increase the shift hyst to 20 it drives not bad at all but this cause the trans not to shift in some situations

I also had some issues with the manual mode, but I can get it to work by pressing longer on the shift buttons to enter the manual mode, it was more responsive before

Thanks
Giovanni

[ashford]

did you remember to configure the project properly

f you choose mixed loads, you also need to activate/deactivate some settings under Project -> Project Properties:

- if you are using TPS for Line Pressure Table/MAP for Gear Tables you should make sure:
-- GEARTABLEMAP is activated, and
-- PCTABLEMAP is deactivated

- if you are using MAP for Line Pressure Table/TPS for Gear Tables you should make sure:
-- GEARTABLEMAP is deactivated, and
-- PCTABLEMAP is activated
These will set the appropriate displays (the load axis index and bins) for the tables in TunerStudio.

If you are using only MAP or only TPS (either of the first two options) you only need to make sure LOAD_KPA is activated (for MAP) or deactivated (for TPS).

[gboezio]

Yes, the gears operate on the right load (TPS), but it's hysteresis seem to operate on Load that stills follow CAN MAP or MAP itself, this make it a bit unpredictable

[gboezio]

So I can't get the gear table TPS and PC MAP to work properly so I have reverted to full TPS and I'm retuning the pressure table, But I like better MAP for PC.

So using full TPS the "load" parameter still follow the MAP value, it is used in some calculations like hysteresis and should load follow the TPS value ??

[Bernard Fife]

gboezio,

If you are asking if MAP is still used for hysteresis if the load is set to 100% TPS, then no, it isn't used for hysteresis, only the load value is (which since you have set it to all TPS, has no MAP component, and it always equals TPS). At least that's how it is designed. It worked that way for me in testing, but if you are seeing something different could you include an your code version number, a datalog, and an MSQ?

Lance.

[gboezio]

Hi Lance, it took me some time to reprogram my TCU backward and to go out get some datalogs and do testing since I had other parts of the Jeep to fix.
So I reverted to TPS gear table and MAP PC control table, this is what works best with my setup, TPS PC table is not adjusting the line pressure to the real engine load and sometimes jerk the truck too hard.

I have adjusted the speed hysteresis to 5 km/h and the load % hysteresis to 10 % and rolled to a speed between 2 nd and 3 rd gear keeping steady throttle and using the brakes slightly to go over and under shift speed, at 374.89 seconds on the log the TCU upshifted due to speed, TPS and speed are kept under hysteresis values, then at 377.86 it upshifted while I figure that the hysteresis should hold that downshift until one of both hyst. values are broken, speed is kept between 2,5 km/h and throttle is rock steady, the MAP does fluctuate a lot and go very close to 10 KPA just before downshift.
Beside this I see that the load value of the controller is still a MAP value, this is why I was asking if this value could be used as hysteresis calculations.

Thanks for taking the time to check this
Giovanni

[Bernard Fife]

Giovanni,

You have speed hyst set to 5 (actually 4.98883) and the load hyst set to 10.0. Looking at your log, the 2-3 shift happens if either of the hysteresis conditions are met. The hysteresis is removed if these ranges are exceeded any time since the last shift. However, since the last shift isn't on your datalog, we can only look at the period prior to the shift to see what we can deduce.

At 364.868 seconds, the speed is 52.1, but by 374.473 it has reached 59.9, exceeding the hysteresis value of 5, and so this would have cleared the hysteresis. So the shift at 374.895 seconds has no hysteresis impediments.

But that raises a question you asked earlier (and that gets to the heart of the matter - I should have understood this sooner - I apologize!), and I answered incorrectly (I was thinking of 5.00x code). The hysteresis is always based on the load value, never the TPS value, even when you use TPS for the gear table (in 5.00x code, the TPS and MAP are combined into a single value used everywhere). I can changed this behavior, and will do so shortly and post a note here (and in the code update thread) when it is ready , likely later today.

Note that the shift in question would still have happened with the upcoming change though, because of the seed hysteresis condition being met. However, since it will behave as you expect, it will be easier to tune such shifts out.

Lance.

[gboezio]

Thanks Lance that shed light on how it operate, I consider the 374 s upshift as legitimate.
I did not expect MAP to still be a factor and the fact it swings wide when shifting with such a long final gearing ratio make the shift behavior a bit unpredictable, I had bad gear hunting before at staedy throttle with V2,2xx and delta speed was less than 1,5 km/h (hyst set to) 10 and steady throttle, but MAP was varying a lot, that made me feel that the MAP has something to do with this, to cure this I had load hyst values of 20, for some reason it's not as bad now

[Bernard Fife]

Giovanni,

Here is some test code:

Monitor_4126t.abs.s19

Uses standard 4.126 INI. USE WITH CAUTION.

(71.04 KiB) Downloaded 865 times

I haven't tested it (my bench is configured for testing something else at the moment, and it is not a trivial matter to switch back). I will do some testing, but it might take a day or two. So if you try this test code, proceed cautiously.

The only change is to add a condition on the hysteresis to allow for TPS to trigger the hysteresis, instead of MAP, when TPS is used as the load index for the gear table. The code is numbered 4.126, and uses the standard 4.126 INI, so you should be able to swap it right in and back as you like. If it proves to be the fix you want, it will be released as 4.127 code after more testing.

If you decide to try it, let us know how it goes.

Lance.

[gboezio]

That should work awesome, I will try this tomorrow AM