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Thread: 6l80E 3-4 shift, Track only, can somebody at HPTuners take a look to see if there is

  1. #1
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    6l80E 3-4 shift, Track only, can somebody at HPTuners take a look to see if there is

    a hidden parameter that control this behavior in the factory calibration? the trans shift perfectly on the street, and according to another thread we had going on with the same issue, as long as the trans can do the 3-4 shift before a WOT run, everything is good: http://www.hptuners.com/forum/showth...ight=3-4+shift

    Please help, this seems to affect G8GT's in general, and no matter what you do, after an engine restart, if you go WOT inmediatly, the 3-4 shift will hang, then complete. it affects Normal and Sport mode, haven't try Manual mode since i let the TCM handles the shifts. once the car has completed a 3-4 shift, then the 3-4 WOT shift works as expected, the shift is crisp and quick as it's supposed to.

    Regards,

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    ive said before what is gonna fix the issue..

    I've also seen other people with corvette's complain of the same issue and letting the car see a 3-4 shift worked for them also.
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    After a re-tune hit the Trans Fast Adapt Button. And take the inertia multipliers on all 3-4 and set them to 0 or 1. 0 Being a value of nothing. 1 being the value set in the original tables.
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    Did you have this problem everytime with the WOT 3-4 shift ?, or only when the car has been parked for about an hour, and you try to make a run (1/4 mile for instance) inmediatly after the engine restart ?

    The last is my issue, my WOT 3-4 shift is quick and sharp everytime when running on the street. in fact i can shuftoff and restart the engine when everything is at operating temp, and the 3-4 WOT shift would complete as expected.
    Dit it today on my way to the office as a test.

    But if if i go to the track, park the car, come back after an hour or so, and get her ready for the run, the WOT 3-4 shift would hang as if was hitting the rev limiter, then she would shift. if i make another pass inmediatly after that one (hot lap) the trans won't exhibit this issue. same thing if i come straight, after the 3-4 shift has completed part throttle, trans would shift as it should at WOT on the 3-4.
    Last edited by bluegoat06; 01-12-2011 at 03:02 PM.

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    Here is the log file i did from this morning test, it has every trans PID i could find and log in it. i did shutoff the engine,(engine/trans at operating temp), waited 20 sec, then restarted the engine, went into sport mode, and gave her a 1-2-3-4 WOT to test if the 3-4 shift was going to hang. it shifted as it should.

    I don't have logs from the track cause i don't seem to find a way to log trans PID's with the standalone. when it hangs, it feels like the rev limiter is kicking in, but it's not the rev limiter, is seems the trans is hunting for 4th gear, it takes about a sec or more to shift right from the shift point where it's supposed to. again, if i hot lap her, the shift comes as it should.

    Seems to be some sort of diagnostic test or something that has to complete before the trans can do the 3-4 at WOT during this particular situation, perhaps the trans is expecting the fluid to be a certain temp, i wish i knew what it is, cause it's driving me crazy.
    Last edited by bluegoat06; 01-12-2011 at 03:03 PM.

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    Same problem with my 08 Corvette. According to my logs 3-4 shifts right at 1 second on the street but at the track 2.03 last Friday night. Has to be hurting my et and mph.

    IDRIVEAG8GT, not sure what Inertia multipliers you are referring. Screen shot maybe? Post a file?
    Last edited by 8850; 01-15-2011 at 08:30 AM.

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    He's referring to the shift time inertia adders, check them to see how they modify your inertia factor profile. i made a little modification to it last week, and i'll give a try at the track next month. i don't think that would be our problem as our trans are shifting like they should except when the engine has been shutdown to allow for a cool down time, and a WOT run is made after that, 3-4 WOT shift only, if you hot lap her inmediatly after the 1st run, the 3-4 behaves like it should.

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    Quote Originally Posted by bluegoat06 View Post
    He's referring to the shift time inertia adders, check them to see how they modify your inertia factor profile. i made a little modification to it last week, and i'll give a try at the track next month. i don't think that would be our problem as our trans are shifting like they should except when the engine has been shutdown to allow for a cool down time, and a WOT run is made after that, 3-4 WOT shift only, if you hot lap her inmediatly after the 1st run, the 3-4 behaves like it should.
    My Shift Time Inertia Adder for my 3-4 including Special is already zero so must not be my problem. Unless you are referring to Shift Time Input Torque Adder for 3-4 and Special?

    Did not log my tranny temp but it shouldn't have been too much lower than normal. Wasn't long before I came off the highway and made my first pass. My engine temp was fully warm in the log.

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    I don't know how it is in the vettes, but on the stock G8's tune, the shif time torque adder is already 0 from the 118ft/lb cells all the way down (3-4 shift)


    Stock shift time torque adder 3-4



    The shift time inertia adder for the 3-4 though is populated with values from 0 through axis 8, axis 9 is 0, so i just wrote a 0 on Axis 8 in the 3-4 normal and special shift time inertia adder like this



    Then i modified the inertia profile for the 3-4 like this (notice the 236ft/lb cells from 4000rpm and up towards the higher ft/lb cells, i made them 8-9)



    Basically the main change was putting the 0 in the axis 8 in the shift time inertia adder (in my case)
    I don't think it'll make any difference at the track for the issue we have, but i'll give it a try in about 2 weeks when i'll be going to the track.

    Again, i don't have any issues on the street with the trans shifting into any gear.
    at the track, after a cool down and engine restart, the first WOT run, the 3-4 WOT shift will hang, then shift, if i hotlap the car, the 3-4 will shift like its supposed to, another thing that seems to work is let the trans do a 3-4 shift at part throttle before the WOT run, if you don't shutdwon the engine after that 3-4 shift at PT, then the 3-4 WOT shift would work.

    This is why i don't think the inertia thing would do anything for us, if the trans is expecting to run a diagnostic test or whatever is trying to do, and it's not completed, then that 3-4 shift will hang.
    Last edited by bluegoat06; 01-17-2011 at 01:00 PM.

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    If you think it's going though a diagnostic test then maybe under Trans Diag, Invalid Torque Signal, perhaps disable Freeze Adapts and Max Pressure. If the 3-4 WOT shift is fine after a PT shift, which mine are as yours are, then your normal settings should be fine.

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    Tried last night at the track under Trans Diag, Invalid Torque Signal, disabled Freeze Adapts and Max Pressure. Did not fix the problem.

    Looking at my logs. 11.224 was a hot lap, never turned the engine off after my previous pass. 11.317 starting from engine off. Looking at frame 6337 (6100 rpm) in log 11.22, from that frame to 6379 (4848 rpm) it takes 1.046 seconds. In log 11.317 frame 2582 (6104 rpm) to frame 2656 (4996 rpm) 1.85 seconds. I don't know why the difference in rpm at shift extension but there is a .804 difference in time even with the higher rpm in 11.317. Had it dropped to 4848 maybe even longer to shift. Something is going on in this transmission. On the street never a problem, always a good shift, but I have always been though the gears first.

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    Thanks for your test 8850, so disabling those diagnostics didn't do anything, and i'll guess the inertia thing didn't do crap either. At least you can hotlap the car, at our 1/4 mile track, (Fontana Dragway), hotlapping would be almost impossible for me given the amount of cars there are during test and tune

    I found an old thread in one the G8 forums i visit from people having the exact same problem back in 2009. For me revving the engine past 6000rpm or so before headers and CAI was not a problem in Manual mode, but after this mods, i'm getting through the traps sooner, so i need to make the shift at least to 6200rpm which is still before the traps.

    http://forum.grrrr8.net/showthread.php?t=5495
    Last edited by bluegoat06; 01-24-2011 at 11:22 AM.

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    Quote Originally Posted by bluegoat06 View Post
    Thanks for your test 8850, so disabling those diagnostics didn't do anything, and i'll guess the inertia thing didn't do crap either. At least you can hotlap the car, at our 1/4 mile track, (Fontana Dragway), hotlapping would be almost impossible for me given the amount of cars there are during test and tune

    I found an old thread in one the G8 forums i visit from people having the exact same problem back in 2009. For me revving the engine past 6000rpm or so before headers and CAI was not a problem in Manual mode, but after this mods, i'm getting through the traps sooner, so i need to make the shift at least to 6200rpm which is still before the traps.

    http://forum.grrrr8.net/showthread.php?t=5495
    I wish the test had worked but so far I still have the problem. It was a rare opportunity that I got to hot lap on that pass where I had the quicker 3-4 shift. Most of the time there are too many cars just as your track.

    Looks like that slow shift is costing mph. I went from 124.19 to 125.83 with the quicker hot lapped 3-4. Although my 60' was just slightly better I think the shift gave me most of the improved et on that pass. My launch IATs were even warmer on the better pass.

    Did not change any of my Inertia tables. Not sure how those tables could have anything to do with this phenomenon but until we know maybe there is something there. I'm hesitant to test anymore as I've got a converter coming so any farther testing may be for naught right now.

    If I still have the problem with the converter I try lowering my shift rpm.
    Last edited by 8850; 01-24-2011 at 01:14 PM.

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    I haven't tested the changes i did to the inertia adders at the track, our next test and tune would be in Feb 8, so i'll let you know if something changes with that regards, on the street, the shifts feels crispy and clean as always.

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    Yes, please do. My Corvette tables are slightly different than your screen shots but if it works I'm sure it will work on mine.

    Do you have a country road you could test on before going to the track? Might be worth et if it takes some modifying before getting to the track.

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    Unfortunately no, i live in Souther Cali, so the roads are always full, i have a couple of "WOT tuning" spots, but i have to get there really early on sunday mornings to enjoy a full hour session , the problem is that is all a Toll Road with nothing around for miles, and at 5:00am in the morning, there is literally nothing, and nobody driving around, which is good for WOT tuning, but in this case i'll have to shutdown the engine for a good while to replicate the cool down behavior, and that's is the problem, a lonely car at 5:00am parked on the side of the road ...

    I've been able to test this on a hot start though with sucess, last week i did a test with the engine at full operating temp, so i coasted down and shutdown the engine, waited for like 30sec before i restarted it, and gave her a WOT run inmediatly after that. the 3-4 was clean.

    If i could only shutdown the engine for about 30-45 min and do the same i'll be gold.
    Last edited by bluegoat06; 01-25-2011 at 11:42 AM.

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    So if you just turn the engine off and make a pass the 3-4 is clean but not so with a 30-45 minute cool down. I have never timed the cool off period so maybe our temperature control tables are some how interacting? Under transmission diag we have over temperature values and under TM a couple. Maybe a shot in the dark.

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    I changed the inertia adders 2 weeks ago,and last week, i was able to test the hot start (I was curious to the see the end results) and i know for a fact it worked that time. i had driven the car for at least an hour in traffic, and i deviated from my original destination since i found a spot suitable for what i wanted to do. engine and trans fluid were at normal temp. shutdown, waited 30 sec, restarted, and did the entire simulation on WOT, clean 3-4 shift.

    I was at the track 3 weeks ago (before the inertia adder change), and was forced to shutdown the engine after letting the 1-2,2-3 and 3-4 part thottle shift complete before staging, and at that time, my 3-4 wot shift hung, then completed. As a note, the engine was cold when i started it, then i did the part throttle shift in the parking area, and came to the staging lines, but had to shutdown the engine after 10min because the lines were backed up. Engine was at normal operating temp for sure, but i don't know how the trans fluid temp was. i'd imagine it won't get hot in 200-300ft from when i drove from the parking area to the staging lane doing 3 shifts at around 25mph, then i threw the trans in park and waited 10 minutes before shutting down the engine.

    So it looks then like the trans fluid temp might be playing a role ?

    I'll take a look at the settings in the trans diagnostic option tonight.
    Last edited by bluegoat06; 01-25-2011 at 08:19 PM.

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    If this has any relationship to TM then setting the TM, Limit TqMgt to 493* might be a solution. Stock on my car is 68*. Althought in my logs I'm not seeing any timing or throttle reduction when it occurs.

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    I've been trying to find more data about this problem, and have checked on the two bigger G8 forums just to find others having exactly the same issue, and having exactly the same outcome when the car is hot lapped (clean shifts). This is not a tune issue unless your 3-4 is hitting ther rev limiter everytime, or when the tires see a little bit too much sppining from the dig, which in any case is completely different than the problem i've posted.

    It doesn't matter who tuned her, or what they used to tune the trans. shut the engine off for about 30 min or so to allow it to cool down, start her up after that, go ahead and do a 1/4 mile pass right away, and your 3-4 would hang, drive her to the staging lanes one more time or as many times as you wish without shutting down the engine, and you'll never know you had a 3-4 shift hanging at wot as the shift would complete as it should.

    The trick so far is let her complete the 3-4 at part throttle going around the parking lot before you do the big run. as long as the trans sees that 3-4 part thottle shift, life would be good. the other is just a hotlap, or letting the trans see a 3-4 shift while doing the burnout. either case, that 3-4 shift is required after an engine restart (depending on how long the car was in cool down mode) before you do the big run. (1/4 mile track). This is the main reason we don't realize we have a problem as the 3-4 WOT shift works like a charm on the street. i've never ever had this problem running on the street. easy to see as the the 3-4 shift would complete upon initial engine start and drive at least once.

    I opened this thread to see if HPT Engineers could look more in deep into the G8 calibration and find is there was a diagnostic test the trans need to run before it can let that 3-4 WOT shift to happen. unfortunately, only myself and 8850 (which also have a car with the same trans) have posted so far, so i doubt HPT would look into it under such circusmtances because well, it looks like a tune issue when in reality, it seems to affect a lot of G8's tuned or not tuned. (at least in my case since i have one)

    It's not the trans running low on fluid, and it's not in the tune, if it was the tune you can bet the house the 3-4 or any other gear would always be erratic, if it was the trans runing low on fluid, you would have more shifting problems in any gear than a single 3-4 WOT shift hanging at the track after a cool down period.

    So let me try this again. Can somebody from HPT please take a look at the G8 Calibration to start, and see if there is a diganostic test in the trans that would make the trans behave like this ?

    I can beat the beejezus out this car anywhere, anytime, and my 3-4 shift would complete like it should without a single problem, EVERYTIME.

    Let her rest for a cool down (30 min or more in my case, i wish i had done more test with less time, but it's usually after the cool down), do a 1/4 mile run inmediatly after that cool down time, and the 3-4 will hang, guaranteed.
    Last edited by bluegoat06; 02-08-2011 at 02:05 PM.