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Thread: 17 f150 torque source "trans shift modulation"

  1. #1
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    17 f150 torque source "trans shift modulation"

    I swapped on an 18 gt intake and if I raise the shift points over 6500 it hits this torque source and pulls the timing back in the low single digits and drags the shifts way out. I have all the torque reduction stuff raised, and if I shift it under 6500 it hits the shifts perfect and stays in driver demand.

    This log was with the shift modulation set to 1.000 in the spark only torque ratio configuration and it made no difference.
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  2. #2
    Senior Tuner veeefour's Avatar
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    It's good that it does that - hard to blow your trans this way...

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    I know what shift modulation is, I just need to figure out whats making it happen here.

    I do know that the map sensor is not getting an accurate reading because of where I have it right now, and I'm gonna fix that, but would the load calculation from the map not reading correctly cause this?

  4. #4
    Senior Tuner veeefour's Avatar
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    Yes as load infers the torque and map infers the load.

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    Senior Tuner metroplex's Avatar
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    This is exactly what happens on my 2018 Explorer XLT - the TRans Shift Modulation torque source pops up and timing gets pulled from 27* advance down to -3* advance for 0.5-0.6 seconds, making it seem like the trans just stalled. My intake manifold and MAP are stock though. But this was the first year Ford went to speed density on the N/A 3.5 V6 for the Explorer (2017 was still mass air flow).

    Also just want to add my N/A Explorer seems to have the same OS/strategy as your F-150. TC-1791. Hopefully you were able to find a solution, would be great to see if it would work on mine.
    Last edited by metroplex; 04-21-2021 at 06:59 PM.

  6. #6
    Senior Tuner metroplex's Avatar
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    Trans Shift.JPG

    Here's an example of what I'm talking about. I can pretty much raise all the upshift limiters for WOT 2-3 and it will still hit Trans Shift Mod and cut spark big time, even with the trans fluid temp fully warmed up. I'm at a loss as to what I need to change.


    EDIT:
    I think I figured it out.

    For 1st and 2nd gear, I never took into account the TCC Slip. By the time the WOT 3-4 and WOT 4-5 comes around, TCC slip is about 0 RPM so the OSS RPM and Engine RPM are a match.
    For the 1-2 and 2-3, I need to command a lower OSS so it doesn't hit some kind of engine/trans limiter which is what I think is causing the spark reduction and the "hitting a wall" feeling that drags out the shift. The OP's comment that when he sets his shift point lower, it went away.
    That's my theory at least and awaits to be tested.
    Last edited by metroplex; 04-22-2021 at 08:19 PM.

  7. #7
    Senior Tuner metroplex's Avatar
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    First test results came back:

    WOT 1-2 seems fine and very snappy. But that darn WOT 2-3 is acting up. This was the first WOT 1-2 and 2-3 of the day but the Trans Fluid Temp is warmed to 177F.
    I commanded a 6700 RPM shift for the 2-3 but it takes place at about 6900 RPM and the shift took 0.8 seconds. You can see how much the torque drops (from about 210 ft-lb down to 141 ft-lb).

    In comparison the WOT 1-2 was not as bad. But if you look down below there is a significant amount of spark cut for these shifts. I don't see any setting that controls this nor a limiter that shows up. Torque Source is "Trans Shift Mod". That WOT 2-3 feels like hitting a "wall" of dead space as it shifts.

    Trans Shift 2.JPG

    After numerous WOT passes, the trans fluid temp is really warmed up. Now the WOT 2-3 is much snappier, taking only 0.3 seconds to complete and the RPM at which it occurs is much better and more of what I wanted. I also attached the torque source, spark source, etc... Pretty much the same as above. Trans Shift 3.JPGTrans Shift 3B.JPG

    I am not sure what is happening here. I don't see this happening with the same 6F55 on the EcoBoost TC-1797 applications. There is no spark cut like this with the EcoBoost V6 engines, not even on the stock tunes. This Explorer exhibited this behavior since day 1 from the factory and I never really knew what was causing it. The WOT 1-2 and 2-3 felt like banging against a limiter or "slipping" for no reason. It always felt better as I thrashed on it and as it warmed up. The EcoBoost V6 6F55's perform consistently whether cold, warm, or fully hot at the drag strip.

    Only difference is the TC-1791 strategy is severely sparse of parameters in HPTuners, whether by design or whether the parameters aren't available. I have noticed this with F-series and Mustang as well even with their 6R80s as long as it was TC-1791. I'm wondering if it is just a coincidence.

  8. #8
    Senior Tuner metroplex's Avatar
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    Still no dice, there's a mystery spark limiter during the WOT shifts. Nothing I do seems to affect it.

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    I have the same problem with my 6r80.

    If you figure it out please post the fix, I'll do the same if I find it.

  10. #10
    Senior Tuner metroplex's Avatar
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    I haven't been able to fix it yet. But here are some new findings:

    I found that at very light throttle upshifts (like taking off gently from a stop light in town, accelerating to 45-50 mph) where it rows through all the gears 1-6, I'll see the "Trans Shift Mod" torque source for each shift with a slight spark cut for the duration of the shift. But at light throttle, that's fine and not really a problem.

    I tweaked the WOT shift tables to lower the shift RPMs for 1-2 and 2-3, and played with the OSS tables. There's slip between the Engine RPM's and Trans Input Shaft from the Torque Converter, so I had to massage the OSS table a bit to account for it. I made a spreadsheet based on trans gearing and RPM that displays the OSS for each cell. But because of the TCC slip, the OSS's for 1st and 2nd gear won't match with engine RPM. For 3rd gear and above with the TCC locked, it will be a close match. The 6F55 TCC almost fully locks in 3rd at above 5000 RPM and even stays locked for the 3-4 shifts.

    But I did a WOT 1-2 the other night and didn't see the Trans Shift Mod nor the spark cut, but the WOT 2-3 exhibited the Trans Shift Mod and spark cut. There's almost no rhyme or reason to this behavior. In the past, if I thrashed it around for several days, doing numerous WOT 2-3 shifts, I'll no longer get the "hitting a wall" feel from the spark cut. I'll keep digging. I lowered the 2-3 RPM more to see if that will correct it. There's 100-200+ RPM of overrun during the WOT 2-3 so even if I commanded a 6500 RPM shift, the engine RPM will get as high as 6700-6800 RPM for that WOT 2-3!

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    This tune runs weird. You have the IMRC set to stay open in the tune. The tune is following the mapped points real strange. It's idling in mapped point 14 and uses the lower MP during WOT. This is causing your engine brake torque to be 130 - 160 ft lbs WOT. Is this how you're wanting to run your truck? Your WOT/OP needs to run in 14+ or you can run 14+ all the time, then your shift torque reduction tables will work as they should. Maybe the reason is because SD isn't correct? Something is causing your load and torque to be half of what it should.

    You've increased the correct areas like you should, but the calculation is so far off, your increases aren't have any effect at all. I would definitely disable 0-13 and run 14+ if you're going to keep the IMRC's open. The same thing happens in 2>3 shift except your torque is around 160 so torque is reduced to around 80ft lbs by spark reduction during the shift.

    atorquereduction.png


    Your low load is why spark is sporadic as well. The timing for the load is good, you could have more advance at those loads, but your load should be at least 20% higher. You're at 55% load, 75% load would be running less timing and there would be no KR.
    Last edited by Thatwhite5.0; 04-29-2021 at 04:33 AM.

  12. #12
    Senior Tuner metroplex's Avatar
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    Quote Originally Posted by Thatwhite5.0 View Post
    This tune runs weird. You have the IMRC set to stay open in the tune. The tune is following the mapped points real strange. It's idling in mapped point 14 and uses the lower MP during WOT. This is causing your engine brake torque to be 130 - 160 ft lbs WOT. Is this how you're wanting to run your truck? Your WOT/OP needs to run in 14+ or you can run 14+ all the time, then your shift torque reduction tables will work as they should. Maybe the reason is because SD isn't correct? Something is causing your load and torque to be half of what it should.

    You've increased the correct areas like you should, but the calculation is so far off, your increases aren't have any effect at all. I would definitely disable 0-13 and run 14+ if you're going to keep the IMRC's open. The same thing happens in 2>3 shift except your torque is around 160 so torque is reduced to around 80ft lbs by spark reduction during the shift.

    atorquereduction.png


    Your low load is why spark is sporadic as well. The timing for the load is good, you could have more advance at those loads, but your load should be at least 20% higher. You're at 55% load, 75% load would be running less timing and there would be no KR.
    Aside from all that he still has the spark cut during the WOT shift.

    My N/A 3.5 V6 only makes about 200 ft-lb at the WOT region so the spark cut takes that way down to like 100-130 ft-lb at times. The question is why is it doing this? Seems to be an issue with TC-1791. I have never experienced this with TC-1797 on engines that produce 400+ ft-lb at that shift region on the same transmission!

    That's like taking the Allison from the 6.6 Duramax, mating it with a Yugo engine and somehow getting torque reduction during shifts when it was shifting fine with the 6.6 Duramax.

    BTW - I lowered the WOT 2-3 on mine to 6300 RPM and after the new flash of the tune, I encountered the Trans Shift Mod and torque cut for the first WOT 2-3 (trans fluid temp was 137F), but on the second WOT 2-3 (trans fluid temp is now 170F) there wasn't any spark reduction.

  13. #13
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    Shift modulation is reducing the amount of torque from 130ft lbs to 70ft lbs by cutting the spark, bringing the RPM down for the next gear.
    It makes sense at different temperatures, you'd get different results. Different viscosities and temps shouldn't be the same. Look over your temperature tables, there's a few important parameters that reference trans temp.
    WOT on this datalog is using part throttle values/cells/torque/pressures. If your vehicles are not reaching those adjusted WOT cells, nothing will change. You have to change the cells that are being ran. In the screen shot I posted above. He increased to bottom two rows to 400ft lbs, but that is not the cells his truck is in. The red box is completely stock and that's the torque his truck is commanding during a shift.

    Since the truck is in part throttle areas of the table, the 1>2 shift is commanded at 6400 Engine RPM, the shift actually begins 7300 Engine RPM, trans shift modulation begins when the RPM fall, bringing the RPM down to 4800. The whole shift from commanded to completed was 2 seconds.
    Last edited by Thatwhite5.0; 04-29-2021 at 11:26 AM.

  14. #14
    Senior Tuner metroplex's Avatar
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    Quote Originally Posted by Thatwhite5.0 View Post
    Shift modulation is reducing the amount of torque from 130ft lbs to 70ft lbs by cutting the spark, bringing the RPM down for the next gear.
    It makes sense at different temperatures, you'd get different results. Different viscosities and temps shouldn't be the same. Look over your temperature tables, there's a few important parameters that reference trans temp.
    WOT on this datalog is using part throttle values/cells/torque/pressures. If your vehicles are not reaching those adjusted WOT cells, nothing will change. You have to change the cells that are being ran. In the screen shot I posted above. He increased to bottom two rows to 400ft lbs, but that is not the cells his truck is in. The red box is completely stock and that's the torque his truck is commanding during a shift.

    Since the truck is in part throttle areas of the table, the 1>2 shift is commanded at 6400 Engine RPM, the shift actually begins 7300 Engine RPM, trans shift modulation begins when the RPM fall, bringing the RPM down to 4800. The whole shift from commanded to completed was 2 seconds.

    Which temp table are you referencing?

    I see what you are saying and looked at your screenshot. I learned that on my Explorer the engine brake torque is about 200-224 ft-lb at 6300+ RPM and where it is supposed to shift at 6700 RPM. Even if I raised the torque mgmt for upshift 1-2 and 2-3 at the 4000-6750 RPM and 150-300 input torque region (basically lower right) to say 400 ft-lb, it will STILL cut it down to 100-130 ft-lb. The shift modulation begins around when the shift is commanded and lasts for the duration of the shift.

    I started lowering the commanded WOT shift tables as well as the WOT region for the OSS schedule tables. I went down to 6500 RPM for 1-2 and so far I haven't seen it really cut-out for the WOT 1-2, whether cold or fully warmed. I lowered my 2-3 down to 6300 and it cut out the first WOT 2-3, but the second time it didn't. There wasn't a TQ+ From Trans or Trans Shift Mod message.

    The N/A 3.5 V6 has stock 6750 RPM shift points but even the factory tune did the severe spark cut out. It looks like Ford used the same tq mgmt upshift tables for the 6F55 across the board regardless if the N/A engine only makes 255 ft-lb max or the EcoBoost makes 350+ ft-lb max on the factory tune.

  15. #15
    Senior Tuner metroplex's Avatar
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    Trans Shift 1.JPGTrans Shift 2.JPGTrans Shift 3.JPG

    So the WOT 1-2 doesn't have Trans Shift Mod or the spark cut. But the WOT 2-3 still has it and I've attached the Tq Mgmt Upshift settings.
    The overall WOT 2-3 took only 0.5 seconds this time and while there was spark cut, it didn't feel as bad. I have been reducing the WOT 2-3 shift point more and more. Factory was 6750, and now I'm at around 6300 with it still overrunning to 6500.

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    I just noticed my mustang has TC-1791. FSGS05A.H32

    I loaded up a canned SCT tune and it bang shifted the 1>2, I mean knock fillings loose shift. I was able to read the SCT tune and found nothing changed from my stock strategy, does SCT have more trans tables?

    I maxed out the TQ reduction tables and under engine>tq management>shifting I zeroed out the shift reduction times.

    Under trans >tq management>general>rate limiting>upper limit I raised all cells to 5217
    I also did a compare with a FRPT2(Ford Racing Performance Tune) file and changed some other parameters I do not recall.

    It now shifts WOT only cutting 4 degrees and it chirps the tires on the 1<2 and the 2<3.

    I'm not sure what actually fixed it

    Here is my stock engine tune and my modified trans tune. Look it over please See if you notice anything that might be harmful but it does shift better.
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    Last edited by K44; 04-30-2021 at 07:49 PM.

  17. #17
    Senior Tuner metroplex's Avatar
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    I actually don't have that Upper Limit table. I've seen it before for the 6F55 on a TC-1797 Taurus SHO tune before but Eric either didn't define it for the Explorer TC-1791 controller or its not there. I already sent in a request but everything I've sent in for the Explorer has been put on their back burner, probably because I'm the only one tuning the N/A Explorer.

    I actually don't have the spark cut for the 1-2 anymore. I think if I drop the 2-3 shift point a bit more it might work out. It's interesting to see Mustangs with the same issue with 1-2 and 2-3 upshifts. It has to be something with the TC-1791 controller.

  18. #18
    Senior Tuner metroplex's Avatar
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    I've been doing more WOT 1-2 and 2-3 tests, and after that first 2-3 where it did clip the spark, the subsequent WOT 2-3's have been very snappy without that torque source or the spark clipping. My WOT 1-2 and 2-3 now take about 0.465-0.485 seconds to complete. Not anywhere as good as a McLaren or Porsche, or GM's 10L80 on the ZL1.

  19. #19
    Senior Tuner metroplex's Avatar
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    I can confirm it doesn't do it anymore. Either I had to have it complete several of these WOT shifts to adapt or something... but after lowering the WOT RPM for the 1-2 it doesn't even do it with the first reflash/cold shift.

  20. #20
    Senior Tuner metroplex's Avatar
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    So my WOT 1-2 now takes about 0.45 seconds and the WOT 2-3 is 0.323 at its best. The weight shift on the Explorer is noticeable during these shifts, it feels like shifting a manual very quickly. I'm not sure if this is good, but I always felt if these automatics were too "seamless" in shifting it meant something was going to burn up.