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Thread: TCC - Lock During Shift

  1. #1
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    TCC - Lock During Shift

    Reading the 1.3 help files and suddenly saw the light on one of the torque converter issues I have.

    TCC Lock During Shift...

    By the name I assumed it meant lock the TCC during shifts. (Which I thought odd, but lets not go there.) Reading the updated help file however I find it actually determines if the TCC will remain locked during a shift. Ahhhh....

    Makes sense of my logged data.

    Does anyone know the ramifications to the torque converter and transmission of leaving the converter locked during shifts?

    At the moment I have a problem at some throttle positions with the converter locking in 3rd, very soon after the transmission shifts to 4th and the TC unlocks, then almost immediately locks again. I can increase the TC apply points in 3rd for those throttle positions so that it doesn't lock before shifting to 4th. Playing around so far, it seems to throw other aspects of the transmission's behaviour out. (i.e., it isn't quite that simple...)

    So now I could also change the Lock During Shift setting so that it doesn't unlock at shifts. (Smooth things out.) I can see that would introduce a problem by itself however. I guess the TCC Lock During Shift setting also effects downshifts - where you tend to want the TC to unlock. I assume by default, 2nd gear lock and release is set at 367km/h across the board. This means 2nd does not lock... but also... does not release either.

    (So I assume if I kick down from 3-2 at anything less than 100%TPS (what my release %TPS vs Speed tables hold), I'll be stuck in 2nd with TC locked....)

    Is there any particular reason 2nd gear TC release isn't (or can't) be set at 1... or some other low number?

  2. #2
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    Re: TCC - Lock During Shift

    Elmis, I can tell you that I have a very similar issue right now. It is the main reason I bought the HPTuner. LS1 Edit description makes it sound like you will always lock the TC when you shift which is bad. however, I have a high stall in a heavy truck so i want the TC to stay locked if locked originally when shifting. yet stay unlocked if it is unlocked just prior to the shift.

    I can also say that playing with lock and release in Edit is a bear and did not seem to work as we thought it should. Hopefully in the next week or so, I will have received my kit and played with it some in a kit that makes more sense.

    I can tell you the results are... With the stall, I gained .2 on my 60' time, yet lost over 2MPH in the 1/4 and ended up with .02 lost time in the 1/4 at least partially by how we tried to handle lockup on the TC.

    One other note, we actually played around with MPH spots on forcing the tranny not to shift into a higher gear until certain MPH so that we could try to get around these issues. And it is only partly working.

    It is quite annoying to be at 2krpm in 3rd and have the tranny shift unlock to 3krpm and then lock again into 1200rpm in 4th. Despite the extra stress on those clutches.


    I feel your pain. I hope to rectify this issue with the HPTuning software soon. We shall see.
    Because it must be Brent!&&\'05 FORD F-250 Diesel, baby

  3. #3
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    Re: TCC - Lock During Shift

    Just out of curiosity, are the values for TCC lock/unlock the same in 4th gear as third?

    If the trans locks the converter in third, shifts into 4th and the TCC MPH apply vs TPS is higher it will unlock until the value in the 4th gear table is met.


    Copy and paste your tables here. I know it works on my truck as the converter stays locked from 3rd to 4th (4l80E).

    Downshift always unlocks the TCC.

    Ken

  4. #4
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    Re: TCC - Lock During Shift

    are the values for TCC lock/unlock the same in 4th gear as third?

    Heres a screen cap of the table (note in kph): http://www.mytired.net/temp/hptuners01.jpg

    I don't know how this table compares to stock - the PCM had been edited previously. I haven't made any lasting changes to it since I got VCM suite. As you can see, the values are different below 31.25% tps.


    If the trans locks the converter in third, shifts into 4th and the TCC MPH apply vs TPS is higher it will unlock until the value in the 4th gear table is met.

    So the TCC release speed has no effect on the TCC lock / release decision making during a shift? I had guessed that if the TCC remained locked during the shift (TCC lock During Shift = True), and the TCC KPH release vs TPS is lower than the current speed, that it would stay locked.

    Downshift always unlocks the TCC.

    That is good to know.

    I set TCC lock dUring shift to true this morning (the only change) and went out to do some data logging. Transmission behaviour appeared much smoother. Graphing this information now however I can see I never got the exact same operating parameters. The TCC never locked in 3rd! A couple runs were just below 25%tps so the transmission shifted earlier. A couple runs were at 26%tps, which has now proven to be just short of what was required to have lock up occur in 3rd. I'll need to log some 27-30%tps runs - so have tee'd up an unenthusiastic wife to spiel off trottle positions figures for me once the traffic dies down.

    On another forum I had it suggested that leaving the TCC locked during shifts was not advised. At the 3-4 shift in the 27-30%tps range revs are around 3000, and the delivered Torque PID is reporting around 300Nm. Dumb question - but is that a risk to a strengthened TC / Trans? Obvious there are other areas where it could be.

  5. #5
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    Re: TCC - Lock During Shift

    I got the software today. Elmis, like you I have values where the release MPH is higher than the apply. Well guess what, it will never apply like that. I first fixed all the performance mode stuff (on my truck it is the Tow/Haul mode) Wonderful. A place to play with the TCC lock and unlock to get a feel for how it might be able to behave. I think I have it in tow haul mode the way I want it for towing a boat.

    Edited: BTW, Keith, my converter is unlocking at downshift as well. I forced it to lock and stay locked and keep the engine rpms up a bit through the speed vs shift tables by gear selection. I tried to reset the TCC release %TPS vs speed to keep it from unlocking... all my numbers were 100 but WOT seems to unlock it wether I like it or not. Is there anyway to force 110% maximum so that I can lock it at WOT during certain RPMs to try to regain some MPH in 1/4 times. I am slipping 300+RPM at WOT near the top of 2nd gear and over 400RPM in 3rd at WOT. Can I fixt any of this with Force Motor requested current, or should I leave this table alone. BTW, I forget, but I think I am seeing around 30% at WOT.

    I plan to finish fixing my tranny first the way I want it, then head on to the engine. I did log some today, you don't want to know what I saw.
    Because it must be Brent!&&\'05 FORD F-250 Diesel, baby

  6. #6

    Re: TCC - Lock During Shift

    Quote Originally Posted by mustbbrent
    I got the software today. Elmis, like you I have values where the release MPH is higher than the apply. Well guess what, it will never apply like that. I first fixed all the performance mode stuff (on my truck it is the Tow/Haul mode) Wonderful. A place to play with the TCC lock and unlock to get a feel for how it might be able to behave. I think I have it in tow haul mode the way I want it for towing a boat.

    Edited: BTW, Keith, my converter is unlocking at downshift as well. I forced it to lock and stay locked and keep the engine rpms up a bit through the speed vs shift tables by gear selection. I tried to reset the TCC release %TPS vs speed to keep it from unlocking... all my numbers were 100 but WOT seems to unlock it wether I like it or not. Is there anyway to force 110% maximum so that I can lock it at WOT during certain RPMs to try to regain some MPH in 1/4 times. I am slipping 300+RPM at WOT near the top of 2nd gear and over 400RPM in 3rd at WOT. Can I fixt any of this with Force Motor requested current, or should I leave this table alone. BTW, I forget, but I think I am seeing around 30% at WOT.

    I plan to finish fixing my tranny first the way I want it, then head on to the engine. I did log some today, you don't want to know what I saw.
    It can't release the converter without locking it first from my recollection.

    My TCC tables in LS1 Edit all show 3rd and 4th release lower than apply MPH settings.

    Elmis - I've been following your thread on the other forum too. I hope you figure it out. LS1 Edit is definately not user friendly for a novice.

  7. #7
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    Re: TCC - Lock During Shift

    Ahhh.. forgot to update this forum thread...

    As Ken outlined, setting TCC Lock during shift did not resolve my issue. After the 3-4 shift the speed happens to be below the 4th gear converter apply point, and above the release point. As I indicated, I'd hoped that since it wasn't below the release point, that it would stay locked. Instead the PCM sees it hasn't reached the lock point in that gear yet, and releases it...

    The next move is to simply match the 3rd and 4th lock points for the 25% throttle position range.

    Mustbbrent - I wasn't sure about your reply. You said you "have values where the release MPH is higher than the apply" like me. I don't have any settings where the release is higher than apply? I'd assumed you meant it around the other way.

  8. #8
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    Re: TCC - Lock During Shift

    Quote Originally Posted by Elmis
    Ahhh.. forgot to update this forum thread...

    ...

    Mustbbrent - I wasn't sure about your reply. You said you "have values where the release MPH is higher than the apply" like me. I don't have any settings where the release is higher than apply? I'd assumed you meant it around the other way.

    Actually, unless I am missreading the table, which I changed now that I have a stock table, I had some places where I the release on one table was HIGHER than the apply in the other table... the converter was not locking. I fixed that. I noticed you had the same kind of thing happening across tables. I forget now which ones. It was in your xls spread sheet.
    Because it must be Brent!&&\'05 FORD F-250 Diesel, baby

  9. #9
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    Re: TCC - Lock During Shift

    Ok...

    After suffering from a lack of time over the last few days, I finally sat down this evening to work on this.

    Started by returning TCC Lock During Shift to false, then matched the 3rd and 4th lock points for the 25% throttle position range.

    Tested - remained unlocked in 3rd, shifted to 4th, had a slight odd hesitation, continued normally for a little, then locked. Graphed, and suspected 4th gear locking point was a little too close to the shift to 4th in that rev range.

    Upped the 3rd and 4th lock points by 1 km/h in the 25%throttle position (that's all it took...).

    Tested - much better... but found it caused a new and similiar problem in the 31% throttle position range. This basically related to the TCC locking as soon as I started to lift off as I neared the 80km/h speed limt. The mix of lowering throttle and sudden lock up surge was unrefined.

    So matched the 31% TPS settings to 25%, and then set the 4th gear lock point for 0-18% to also be the same.

    Tested - seemed to work.

    Will need to drive for a few days, but it has been a good step forward. Odd how little changes can have such a big effect on the road.

    The only problem.. this seems to have re-triggered an surging issue I've had between 80 and 90km/h at 0% throttle. I'll post about that elsewhere. One step forwards... two steps back.

    (Oh, I'm liking this tool more and more...)

  10. #10
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    Re: TCC - Lock During Shift

    Quote Originally Posted by Elmis
    The only problem.. this seems to have re-triggered an surging issue I've had between 80 and 90km/h at 0% throttle. I'll post about that elsewhere. One step forwards... two steps back.
    Decel fuel cutoff.

    Those tables and constants will be in our next update.


    Ken