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Thread: shift pressure in D vs Shift pressure in L/1

  1. #1
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    shift pressure in D vs Shift pressure in L/1

    I have an automatic cobalt ss 2.4
    The transmission (4t45e) on stock tune settings seems to have a very firm shift from 1 to 2 when set in L and t/c is off. I've since changed the transmission settings to have more exact shifts and increaded the tcc duty cycle. The thing is when I now set it in L to set off for a blast it uses a seemly very weak shift pressure when going from 1 to 2. However if I leave it in D and put the handbreak on one notch to disable TC the shift is nice and firm.
    Anyone have an idea why the shift pressure in L became weak? Other than that small problem I couldnt be happier with the settings I've worked across.

    My only last suspicion is that its in the upshift br/pwrOn table

    Attached are the tables I changed.
    (also shift lock is enabled)
    tcc-max is at 100%
    Last edited by viceroykarl; 05-27-2011 at 03:37 PM.

  2. #2
    Advanced Tuner Dr. Nopps's Avatar
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    Could you post up a copy of your tune too?

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    Sure thing. Sorry for the delay I was at the indy500. I've been messing with some values even more. Mostly smoothing out the shift firmness for casual driving so its less jerky. Those changes wont be in there yet though since I havnt yet tested them.

    EDIT:
    Just so you know It was done in the beta software so you will get an error opening it if yours isnt also the beta. Just request a beta download from support.
    Last edited by viceroykarl; 05-31-2011 at 03:47 AM.

  4. #4
    Advanced Tuner laser_racer's Avatar
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    Your shift pressure looks really low on your car. Here is a copy of a 2.4 I did. You should only modify tables the car use to shift. Like tables B and tables X are the ones the car uses.

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    Are you sure about Pattern B? On my stock tune all Pat. B tables are filled with 318. My shifts for lower torque are pretty low but it feels like its shifting at 90psi.

    EDIT:
    On a side note what mods are done on that car? I noticed the command afr and cam timings were radically different.

    This is my full tune attached.
    Last edited by viceroykarl; 05-31-2011 at 06:20 PM.

  6. #6
    Advanced Tuner laser_racer's Avatar
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    O sorry yes it is A. If anything you could try and go back to stock to see if that helps your car out any.

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    I made some more changes and upped some shift pressures. Still havnt nailed it down. I've attached my full tune above in my last post with the changes. If i leave it in D and just pop up the hand break one notch to disable Traction Control it shifts nice and firm though. Its somewhere using different settings when in L/1 on the shifter.

  8. #8
    Advanced Tuner laser_racer's Avatar
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    Sounds like torque management problem. Your not getting knock or anything when you drop it in low are you? Can you post a log with using both methods and showing which gear you are in?

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    Yeah i'll have to do that tomorrow. Sadly I have to find a new place to test until the street sweeper hits my normal testing road since its still has grit on it from winter. its a road in the middle of nowhere thats exactly half mile long and flat. someone went and painted a start and finish line 1/4 mile apart

    My KR has been taking off timing when I drive around. but it seems to do that anyway even when on the stock tune so I dont really know if its real knock or if its being overly sensitive. I've pulled back the timing from that last posted tune like 5 degrees to reduce kr from kicking in more often. Also changed PE to work to give 12.9 afr under WOT around 2.5k rpm and upwards.
    Last edited by viceroykarl; 06-01-2011 at 01:55 AM.

  10. #10
    Advanced Tuner Dr. Nopps's Avatar
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    I would also suspect that Upshift Br/PwrOn table "X". Try tuning that one the way you tuned your other tables. Going out on a limb here, but you could try disabling Diff Score and Adaptive Pressure Upshift just to see what happens. I noticed your part throttle shift values for 100% TPS don't match up with your full throttle shift values. I would adjust the full throttle shift values so they sync. Also, your Default Base Shift Pressure vs. TPS values climb above the 90.5 limit. Hope this brianstorming helps as my tranny is so different I don't have Shift Lock, or use TCC in 1st 2nd or 3rd gear! There's also some things under Transmission Diagnostics regarding invalid torque signal and commanded gear control limits that I don't know much about, but you could experiment with them to see if they are holding you back.
    Last edited by Dr. Nopps; 06-01-2011 at 04:38 AM.

  11. #11
    Advanced Tuner laser_racer's Avatar
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    Quote Originally Posted by viceroykarl View Post
    Are you sure about Pattern B? On my stock tune all Pat. B tables are filled with 318. My shifts for lower torque are pretty low but it feels like its shifting at 90psi.

    EDIT:
    On a side note what mods are done on that car? I noticed the command afr and cam timings were radically different.

    This is my full tune attached.
    That car was on e85 with a tvs.

  12. #12
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    I've made some changes to it and it seems to be slightly better. The problem is I think im going backwards here. I was getting 7.5s to 7.8s on 0 to 60 times but now its in the 8.2s. It might be that its a pretty hot day and my intake air temp was around 100 deg F. Fingers crossed. I'll test it again at night when it gets cooler since thats when i did my pre-tests before changing things.

    here are the 2 logs of the 2 runs with the hand brake and with it set in low. I have desired shift pressure logged and it seems it uses a lower desired shift pressure when in low compared to when in drive.
    Also attached is the most up to date tune on the car.

    On my test in drive there was a bit of KR but i have the spark cut back as far as i wana go right now since its cut back on calcuated hp by about 17. ( have it calculate hp delivered from torque delivered pid); I had much less kR on my second run in lowdrive since the IAT was around 95 deg F since the car had been moving around after the first test without sitting as long. However the 0 to 60 time was still similar.
    About 8.237 with the lowdrive setting and about 8.221 with the handbrake setting. with peak calc'd hp of 147
    Before the changes and an IAT around 75 deg F it did about 7.592s with a peak calc'd hp of 163.80.

    Would the differences in intake air temperatures make this big of a difference or did i change some things for the worse?

    EDIT:
    Tested again when it got cooler and the IAT was lower this time and the car was back on form. Im pretty surprised how much the IAT can make a difference.
    Made some changes that perfectly smooth out causal driving form me so I'll update the attached tune file.

    Whats weird is now im having this issue where it doesnt want to shift. It holds its rev up with my foot down but the shift to the next gear never comes. Usually happens when a shift from 2nd to 3rd is supposed to happen. I'll also attach that log as odd-shift.hpl
    It started happening after i moved the shift rpm to 7k rpm and the engine cut off at 7200 rpm. For some reason its sitting around 6.8k to 6.9k rpm and the shift never happens.
    Last edited by viceroykarl; 06-01-2011 at 10:27 PM.

  13. #13
    Advanced Tuner Dr. Nopps's Avatar
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    My car would delay properly shifting like that untill I matched up the Full Throttle Shift MPH tables with the settings found in the Full Throttle Shift RPM tables. Carefully watch what speed you're going at 7000 RPM in a gear and enter that as the maximum MPH. Noticed your max Shift RPM values are still set to 6500! And fuel cutoff is happening at 6900 untill you're back down to 6800, but you want a 7000 "redline" right? Also what would happen if you raised those Commanded Gear Control Limits under Diagnostics to agree more with your desired operating ranges? Looks like you're definately trying to operate outside of what that table would allow/limit you to do given it's current settings.
    Last edited by Dr. Nopps; 06-02-2011 at 11:51 PM.

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    hmm thats odd. I may have uploaded the wrong file. Here is the one im working with now. I should have those shift rpms set at 7k

    Though it still seems to shift at 6.6k rpm despite the changes.
    Last edited by viceroykarl; 06-02-2011 at 07:59 PM.

  15. #15
    Advanced Tuner Dr. Nopps's Avatar
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    Latest tune looks a little better. Still try adressing all the stuff/tables I mentioned earlier. This one may turn out to be a pain in the but process of elimination type thing.

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    Quote Originally Posted by Dr. Nopps View Post
    My car would delay properly shifting like that untill I matched up the Full Throttle Shift MPH tables with the settings found in the Full Throttle Shift RPM tables.
    Not sure what you mean there
    What i;ve done was set up the full throttle shift speed tables and the full throttle shift rpm tables for the appropriate settings. ie shift speeds at 41,75,122 and shift rpm all at 7000
    also went though the partial throttle shift speed Normal table too for 94% throttle pos. and greater also to 41.
    Its made shift from 1 to 2nd happen consistently but 2 to 3 is still hanging

    Also the max command gear thing in the diagnostics settings is for only for when your using the VCM controls in the scanner suite to tell the transmission to be in a specific gear. Upped it anyway though just for good measure.

    I've attached as scan log from this tune and at 3 minutes and 18 seconds in is when i punch it and it shifts fine into 2nd but 3rd happens after some delay. Not sure why though. The wot shift speed and partial throttle shift speeds for 100% match up and its not showing any engine cutoffs in the scanner. It throttles back the throttle though. I may disable ETC control for cut off to force it to use fuel cut since i can log that easily. Though i thought fuel cut type logging would show etc/fuel/spark
    Last edited by viceroykarl; 06-03-2011 at 05:15 AM.

  17. #17
    Advanced Tuner Dr. Nopps's Avatar
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    Sorry, when I typed that I was looking at the first "wrong" posted tune.


    When looking at the 2nd one yeah shift-points & fuel cutoffs looked awsome. Again my tranny's not controled like this and just thinking of anything that I know won't actually hurt/destroy it. lol. I actually don't like using TCC at all in 1-3, but that's not going to be it. (you're already lovin it in "D") Again brainstorming out on very far limbs, but if you re-enabled the ability to revert to default shift pressure table but tune that table as long as you have access??? What is Adaptive Pressure Upshift? I don't think there's anything left in there that even sounds like it could affect you after that, right? The other guy knows more than I, and he told you not to touch the other tables, but I can't believe this hasn't been figured out before!
    Last edited by Dr. Nopps; 06-03-2011 at 07:07 AM.

  18. #18
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    Its turning out to be quite a tough nut to crack here. I'll see how things go today. I've set it to disable ETC for engine rpm control. It'll now only use fuel cut for rpm management so I'll know for sure if its something to do with the rpm management. Its not telling me its doing any limiting but it looks like it is since its cutting the throttle on me when it comes time to shift into 3rd.
    I think the adaptive shift pressure allows it to use pressures in between the set pressures at the various torque levels rather than just snapping to the set values at each torque level.
    I'll see what happens if I re-enable its default shift pressures on invalid torque signal in trans. diagnostics again.

    In a few weeks Im due to get new cams/springs/valves and a neutral balancer from zzp so i'll be able to rev higher. Maybe that'll show what is really happening when Im able to set the rpm limit a bit higher without destroying the valve train
    Last edited by viceroykarl; 06-03-2011 at 02:41 PM.

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    Well after logging ETC TgMgt type, FuelCut TgMgt Type, and Spark TgMgt Type im finding that during the shift from 2 to 3 all 3 are showing a Trans cut type. Not sure what TgMgt means though but I suspect its torque management. However the same shows for the change from 1 to 2 but not nearly as long. I've attached the log output and its at 5m22s

    It may just be taking its sweet time for the shift

  20. #20
    Advanced Tuner Dr. Nopps's Avatar
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    Yeah I saw that ETC Mngmnt. pop on for a second. I've got my shift times set to 0.156 (you were worried it was taking it's time) where it used to be slipping and 43-45 max pressure but that's just my preference. Sorry still might not help, as whatever times you're using in "D" seem to work fine for you. Just in freakin "D" !! Looks like you could turn that off under Engine/Fuel/Cutoff-Control Method ETC= enabled... if you hadn't already found that by the time I'm done typing.
    Last edited by Dr. Nopps; 06-04-2011 at 02:21 AM.