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Thread: Trans Shift Mod torque source?

  1. #1
    Senior Tuner metroplex's Avatar
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    Trans Shift Mod torque source?

    Working on my 2018 Explorer XLT w/ the 6F55 (N/A 3.5 V6 not a whole lot of torque). I think the source of the laggy shifts is these 0.5 second events. Torque source is "Trans Shift Mod". Throttle plate isn't closing. Spark is being reduced. Before the shift it is 24* and cuts down to 3* advance.

    Looking at my SHO and Fusion Sport datalogs, those 6F55 don't have this long of a delay in between shifts.

    Is this due to the upshift torque reduction or something else? The N/A V6 makes less torque at the WOT shift points and I don't think it needs any torque reduction. This same trans is used on EcoBoost applications making 300-400 ft-lb at the shift points, and this N/A barely makes 200 ft-lb at the shift point.
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    Quote Originally Posted by metroplex View Post

    Is this due to the upshift torque reduction or something else? .
    Correct
    Knock Retard is the reduction or prevention of knock by lowering ignition timing:

    (+) Adding Knock Retard = Reducing Timing. PCM is seeing knock.
    (--) Lowering Knock Retard = Increasing Timing. PCM isn't seeing knock.
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  3. #3
    Senior Tuner metroplex's Avatar
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    My plan is to set the WOT region for 150-300 input torque to about 300. My engine doesn't make anything more than 200 ft-lb (according to the datalogging PID) so I'm not sure any torque reduction during an upshift is needed with this engine?

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    Assuming that 6F55 has got all the same parts as the EcoBoost variants I'd think you would have a bit of wiggle room to play. I'd still be a little conservative just in case.
    Knock Retard is the reduction or prevention of knock by lowering ignition timing:

    (+) Adding Knock Retard = Reducing Timing. PCM is seeing knock.
    (--) Lowering Knock Retard = Increasing Timing. PCM isn't seeing knock.
    __________________________________________________ ________

    2014 Mustang GT Premium. VMP Gen2R Supercharged with an FTI 3000rpm Converter. JLT, BMR, Steeda, Viking, etc.
    Don't fix it if it ain't broken | Maximum effort gets maximum results

  5. #5
    Senior Tuner metroplex's Avatar
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    I have noticed that the trans still cuts spark big time during the WOT 2-3, but my *guess* is that the Trans Fluid Temp hasn't reached a certain value. At 100F-140F, it seems to still cut out a bit. Once it is above 150F it seems a lot better, but I recall if I do this a few times it somehow doesn't do it again in the future. I am almost positive it has something to do with the Trans Shift Mod torque source or TQ+ from Trans torque source which results in massive spark cut (from say 27* final to -3* final) and not throttle blade closure. This engine makes about 200 ft-lb at 6800 RPM for WOT shifts, so when the spark cut hits, the torque drops a lot and this happens for about 0.5-0.6 seconds initially.

    I don't see a Cold Shift table for my particular strategy.

    Also under Torque Management Spark Only Torque Ratio, I see Shift Modulation and Trans Torque Increase set to 0. I've experimented with setting Shift Modulation to 1 and haven't noticed any difference.

    I'm guessing I need to massage the torque reduction, but I've already set the Torque Reduction tables appropriately - it either needs to "learn" or has to reach a temp threshold?

  6. #6
    Senior Tuner metroplex's Avatar
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    I can pretty much confirm it is some kind of torque limiter for the WOT 2-3 and only 2-3, not temperature dependent.

    I did several WOT 1-2 and 2-3 shifts from when the trans fluid temp was 110F up to 180F. The WOT 1-2 seems to go fine and with the Torque Reduction raised for 5250-6500+ RPM (at all torque input rows), the Torque Source for the 1-2 is always Driver Demand.


    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.

    For some odd reason I never had an issue with my 2014 SHO. Looking more closely at my logs, my commanded/intended WOT 1-2 and 2-3 Engine RPM is never met, it always shifted short and I never figured out why but it never hurt my 1/4 mile times either. The OSS RPM delta always matched the TCC slip RPM...

    Then my 2017 Fusion Sport and 2018 Explorer both exhibited issues with these WOT shift points as well. Looking at these logs, its also matching the TCC slip RPM.

    My theory: Basically assuming no slip in 1st and 2nd, I was commanding too high of an OSS and it would hit the engine/trans limiter. If I command a lower OSS WOT point it should be fixed.
    Last edited by metroplex; 04-22-2021 at 08:21 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.

    Attachment 109172

    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. Attachment 109173Attachment 109174

    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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    I've tried a number of things and there's still a phantom spark cut / torque limiter for the shifting.

    What pisses me off the most is that the same trans in EcoBoost applications doesn't have this problem. I am almost sure it is an undefined parameter somewhere but I've sent in a number of tickets for this application in the past and it is always on the back burner. I know it is missing the Spark Authority tables that I see in other TC-1791 applications.

  9. #9
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    It may be an undefined trans oil temp based table that's used in your Explorer strategy but calibrated differently (to not do anything) in your Ecoboost. Weird that it's not in every gearshift though but there may be some mechanical differences even though they are the same model transmission too... I'd lean more towards the tune or both.
    Knock Retard is the reduction or prevention of knock by lowering ignition timing:

    (+) Adding Knock Retard = Reducing Timing. PCM is seeing knock.
    (--) Lowering Knock Retard = Increasing Timing. PCM isn't seeing knock.
    __________________________________________________ ________

    2014 Mustang GT Premium. VMP Gen2R Supercharged with an FTI 3000rpm Converter. JLT, BMR, Steeda, Viking, etc.
    Don't fix it if it ain't broken | Maximum effort gets maximum results

  10. #10
    Senior Tuner metroplex's Avatar
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    I tried a bunch of different things but that Trans Shift Mod shows up only for the WOT 1-2 and 2-3. The 1-2 doesn't feel too bad but the spark cut is there. The 2-3 can take 0.8 seconds to complete! The WOT 3-4 functions like EcoBoost, no spark cut or Trans Shift Mod and was fast and smooth. No correlation with Trans temp because even fully warmed up with TFT at 200F, it was doing this.

    So I think you are right that it is some kind of limiter for the NA Explorer strategy.

    I've racked my brain over this the entire weekend and haven't made any progress. Usually when this happens it is some kind of undefined parameter or table.

  11. #11
    Senior Tuner metroplex's Avatar
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    I reduced the WOT 2-3 shift RPM from stock 6750 to 6500 RPM. It still does the spark cut but not as bad, from 27* advance gets cut to 10* advance (instead of -3* or 0*) and the trans wasn't even fully warmed up this time around.

    I still think there's an RPM and/or torque limiter somewhere for the 1-2 and 2-3 only.

  12. #12
    i know you dont like posting the tune but can you send it to me to look at?

  13. #13
    Senior Tuner metroplex's Avatar
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    Trans Shift 3.JPGTrans Shift 2.JPGTrans Shift 1.JPG

    After lowering the WOT 1-2 and 2-3 shift points, the 1-2 seems to be fixed. The 2-3 still encounters Trans Shift Mod. Stock 2-3 was set for 6750 from the factory, I've now set it to 6300 and may slightly drop the OSS table a bit more as it still seems to be overrunning to 6400-6500 RPM. No rhyme or reason.

  14. #14
    Senior Tuner metroplex's Avatar
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    Figured I'd update this:

    A fellow tuner and I compared notes and found the same oddity with similar/same applications. Upon flashing a new tune, something resets with the PCM/TCM where that WOT 2-3 takes about 3 times before it "adapts" to something and stops cutting spark during the shift.

    The first 3 times for the WOT 2-3, it will go into Trans Shift Mod as torque source, and cuts the Torque to 150-160 ft-lb with a massive spark reduction. A few times I'll see TQ+ Trans just prior to the Trans Shift Mod. Either way, it feels like a transmission issue until you look at the data. Spark would be 20*-25* advance at WOT until it his this reduction, and when the spark drops to single digits (or even negative) it feels like you hit a wall. But do this about 3 times (in however number of drive cycles it doesn't matter, just need to do it about 3 times total) it goes away. Trans Shift Mod is still the torque source for the WOT 2-3 but the spark reduction slowly goes away and the torque cut goes to about 200-215 which is similar to the other gears.

    The WOT 2-3 is the only problem area, and since this is a 6F55, I figured it should follow the same behavior as other 6F55s but this is NOT the case. My 2014 SHO 6F55 and 2017 Fusion Sport 6F55 don't have this problem and produce like 400+ ft-lb of torque. This N/A 3.5 makes about 255 ft-lb torque max, so there's zero reason for this much torque reduction and only on the WOT 2-3. I understand this is where it switches from the One-way clutch 1-2 to a clutch to clutch shifting for 2-3 and beyond.

    HPTuners tried looking into this but gave up and said I needed to provide more parameters/tables for them to look at, but how can I do that when half the tables are missing. I tried buying the database for my Explorer via SCT since I have their Pro Racer Package. But they've neutered the Pro Racer Package to the point I have to drop 1 of the 3 databases I already own in order to make room for this, as well as show proof of ownership of the vehicle (state registration) as well as the other hoops I had to jump through to unlock parameters in general. But SCT's parameters are normally all unlocked, just not as well organized.

    In any case... I believe there is an additional table that defines this WOT 2-3 torque reduction not covered by the Torque Management Upshift tables. We've both tried raising those values without any positive changes. it immediately cuts torque to 150-160 ft-lb so I know for a fact some hidden table is doing this. HPTuners did a poor job defining everything for this TC-1791, as there are a bunch of tables missing for its 6F55 that are in other 6F55 tunes for TC-1797. I sent in parameter requests in 2021 but haven't heard back, so I've all but given up.

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    Advanced Tuner skylinedan's Avatar
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    And how many years has it been since someone brought up the adaptive tables not being populated ? LOL. I agree with the three shifts at WOT though, I do a flash and the first few times it shifts like garbage, but then things level out, temp plays a big part in this also. Watch it, and make note of how it changes. Seems like all the stock files are set at 160*, I took mine down to 140, helps get the trans shift better sooner.

  16. #16
    Senior Tuner metroplex's Avatar
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    Quote Originally Posted by skylinedan View Post
    And how many years has it been since someone brought up the adaptive tables not being populated ? LOL. I agree with the three shifts at WOT though, I do a flash and the first few times it shifts like garbage, but then things level out, temp plays a big part in this also. Watch it, and make note of how it changes. Seems like all the stock files are set at 160*, I took mine down to 140, helps get the trans shift better sooner.
    What's 160 degrees stock? Or are you talking about 160 lb-ft?

    I don't have this issue on the Fusion Sport and definitely not the SHO. SHO was good to go right after a tune. Fusion Sport might have some oddities but definitely not like the torque cut for the 2-3 like on the N/A Explorer.

  17. #17
    Advanced Tuner skylinedan's Avatar
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    I'm talking about TFT, I don't care about torque output. You raise all your limiters to a respectable level, and it should be better. I would say your missing something, and it may not even be in the trans side of things.

  18. #18
    Senior Tuner metroplex's Avatar
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    A few of us have maxed out the torque reduction limiters and it still cuts the WOT 2-3 down to 150-160 ft-lb during the first three WOT 2-3 shifts. Like clockwork.

    Not sure about keeping the trans fluid that cold. I don't have issues with the TFT overheating in the summer as I have tweaked the fan setting so that it helps regulate the ECT and TFT better.

    I know there's a parameter somewhere that's not defined. HPTuners isn't much of a help. There's just not as many defined parameters on the N/A 3.5/3.7 TC-1791 strategy versus the TC-1797 with EcoBoost like on the Fusion Sport. On a guess I'd say there are probably more than 100-200 extra parameters defined on the Fusion Sport versus the N/A Explorer/PIU.