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Thread: 4l80e will not make the 1-2 at the dragstrip (WOT)

  1. #1
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    4l80e will not make the 1-2 at the dragstrip (WOT)

    Help!! Several tuners and no luck. I have tried moving the shift RPM up and down, MPH also. Trans is a fresh build and should hold 1000hp no issue. Car makes 800 plus to wheels. Tune is attached for review.
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  2. #2
    Tuning Addict blindsquirrel's Avatar
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    Rear gear? Tire size? Converter stall? Log showing your RPM vs MPH? Have you dialed in the speedo, using GPS as a true reference?

  3. #3
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    305/45/17 rear tire, speedo verified by gps; 3.27 rear gears. The converter is 3600 pro torque. I have also tried overfilling by 1 qt.
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    Last edited by rhackstall; 03-14-2023 at 04:00 PM.

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    Add speed sensors, shift times and pressures to your log for the trans. Turbine is an important one.
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

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  5. #5
    Senior Tuner Lakegoat's Avatar
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    Look at Speedo--Calibration--VSS pulses. Both of those should be 40. I don't know if you are using ISS, if not set that to 0.
    The pulses per mile look a little light also.
    Look at the differences in your scan--look at RPM and Speed in Channels and then in Charts. They should be the same. One spot, rpm in charts is about 6500, and almost 7000 in channels.
    Does the trans shift ok at normal driving?
    Under Trans--Shift General--Shift Pattern Type--Pattern A, has selected Pattn2. I don't see a pattern2. Is that reference for another trans type?
    And your speed and rpm has to be lower than the required shift points.
    Use your cursor on charts to move along your wot run and you will see the speed and rpm that you need to be selecting. After you get the channels/charts difference fixed.
    Last edited by Lakegoat; 03-14-2023 at 07:07 PM.
    2000 Camaro SS 2015 L83 port injected, Whipple 3.0, 4L80E, 8.8 Ford
    2013 Silverado 5.3, 6L80k 8.8

  6. #6
    Senior Tuner kingtal0n's Avatar
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    I'd also like to add that

    1. The shift needs to be commanded way before the actual shift occurs. The difference between commanded and actual is based on acceleration and fill rate of the drum (pressure and volume flow)
    For example
    Commanded at 5000, actual at 5200 with 300rwhp
    Commanded at 5000, actual at 5600 with 500rwhp

    The exact time of shift will vary with acceleration because the time it takes to fill a drum is basically static while the amount of acceleration varies with power (if you have more power and faster acceleration, the drum doesn't fill faster to compensate after a commanded shift)

    2. Recommended: Set one qualification low, like MPH, and shift based on ONLY RPM. Don't try to simultaneously meet rpm AND mph for a shift.
    For example
    Desired shift: 6000rpm and 40mph
    Commanded shift MPH: 30mph
    Commanded shift RPM: 5400rpm

    3. After a rebuild you MUST put a transmission pressure gauge on the pressure port to dial in the shift pressure. You can't use a stock shift pressure table it may not be sufficient based on trans mods.
    For example a common 4l80e mod is the lube to line or lube to line PR valve. This will allow pump pressure bleed into the cooler circuit regardless of PR valve position 'unbalanced'. That means all of the commanded pressure from the original table will be reduced by some percentage perhaps 10 to 20% less actual pressure, the commanded 'Force motor Current' needs to be increased across the board to prevent slippage. You wouldn't know unless you have a pressure gauge on the side of the transmission.

  7. #7
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    Quote Originally Posted by Lakegoat View Post
    Look at Speedo--Calibration--VSS pulses. Both of those should be 40. I don't know if you are using ISS, if not set that to 0.
    The pulses per mile look a little light also.
    Look at the differences in your scan--look at RPM and Speed in Channels and then in Charts. They should be the same. One spot, rpm in charts is about 6500, and almost 7000 in channels.
    Does the trans shift ok at normal driving?
    Under Trans--Shift General--Shift Pattern Type--Pattern A, has selected Pattn2. I don't see a pattern2. Is that reference for another trans type?
    And your speed and rpm has to be lower than the required shift points.
    Use your cursor on charts to move along your wot run and you will see the speed and rpm that you need to be selecting. After you get the channels/charts difference fixed.

    Unfortunately, I am having trouble following most of this. I am new to tuning.

  8. #8
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    I will have to get a gauge on it. I already tried lowering the rpm and mph.

  9. #9
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    Get a 0-5Volt 400 PSI sensor and wire it to your EGR input so you can datalog the pressure.
    It makes tuning trans pressure a good bit easier.
    Also the clearances inside the transmission can make a difference.

  10. #10
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    VSS pulses per mile should be 40
    Tuner at PCMofnc.com
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  11. #11
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    You were spinning in the log. you also might be tagging the acceleration based rev limiter. Look for ECM 12067 and zero it out.
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  12. #12
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    thanks to everyone. I made the changes suggested so far and will test it Friday night.

  13. #13
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    Quote Originally Posted by GHuggins View Post
    Add speed sensors, shift times and pressures to your log for the trans. Turbine is an important one.
    my next logs will include these, thanks

  14. #14
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    pulling the trans, something has to be wrong. Still no luck on the 1-2 shift at the racetrack

  15. #15
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    I have a 4l80e that is built to hilt in my stepside.. Controlled by compushift standalone
    During raceweek a few years ago, it mysteriously decided to not upshift from 1 -2 at WOT...
    Lost in finals of Dragweek so that sucked.. Had to let off throttle before it would shift...
    Limped it home, cooked the clutches, etc...
    THE CAUSE: the stupid $.1.35 "fork" that holds in the EPC to the valve body broke off at the tip and allowed
    pressure to bleed off... That led to over $5K spent before the whole fiasco was resolved..
    Very very simple mechanical thing can ruin your day *week*

  16. #16
    Senior Tuner kingtal0n's Avatar
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    Yeah thats why we always need a pressure gauge or sensor on the transmission for tuning purposes

    Most of the shifting decision making is on the valve body and accessible from under the trans. If it shifts 1-2 in normal driving and has good pressure then likely the WOT stuff can be fixed electronically or from the valve body. It is very unlikely there will be some issue internal which prevents a WOT shift 1-2 while allows part throttle shifts. All the 1-2 is the intermediate clutches coming on. If they come on properly and rapidly the trans will shift nice and firmly, even a stock 4l80e with OEM style clutches will handle 800rwhp and shift firmly with the right pressure on OEM intermediate parts. It's not like the 4l60 or 700R4 with the band and servo bs playing a role.

  17. #17
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    Quote Originally Posted by kingtal0n View Post
    Yeah thats why we always need a pressure gauge or sensor on the transmission for tuning purposes

    Most of the shifting decision making is on the valve body and accessible from under the trans. If it shifts 1-2 in normal driving and has good pressure then likely the WOT stuff can be fixed electronically or from the valve body. It is very unlikely there will be some issue internal which prevents a WOT shift 1-2 while allows part throttle shifts. All the 1-2 is the intermediate clutches coming on. If they come on properly and rapidly the trans will shift nice and firmly, even a stock 4l80e with OEM style clutches will handle 800rwhp and shift firmly with the right pressure on OEM intermediate parts. It's not like the 4l60 or 700R4 with the band and servo bs playing a role.
    Wondering if it could be a ecm issue?

  18. #18
    Senior Tuner kingtal0n's Avatar
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    Of course an ECM can just be crazy, from Faulty wiring. Low voltage. Bad solenoid. Trans can be Leaking internally = Low pressure. Solenoids can fail from Poor grounding and low voltage. ECM can have a Corrupted file. burnt board.

    Usually the OEM ecu is pretty cheap. So is OEM harness stuff, at least for mine. I always keep a spare ECU handy its like $35 or whatever. You can continuity test the wiring. Resistance test solenoids. Make sure its got at least 12.5v around there. Check the grounds around the ECU, follow the 'star' grounding scheme from Haltech diagram.
    https://www.haltech.com/news-events/...dos-and-donts/

    Blindly replacing things is cool when its cheap and easy and there isn't much easier than changing an ECU, put a new file in it, I would start from scratch.

    The trans is pretty simple, 4l80e is one of the simplest automatics I've ever seen, and second gear is the easiest gear, just fill the intermediate piston crevice with fluid rapidly with the right pressure. Shift kit plates can leak and the little hole for the over-pressure is known flaw which can leak, I don't use the shift kit plate and I never drill the trans-go spring assisted over-pressure hole either, it might be blowing open at wot causing low pressure and no shift. You would see it on the pressure log if logging pressure as suggested above. If the trans is apart inspect the planetary and mating surfaces, I use a file to smooth any flash or rough case materials, puting the trans together often easy to overlook these slight flaws as we install and remove the lower half of the 4l80e to set rear bushing/bearing clearance for example, some of the case can become a bit chewed up, could interfere with rotating parts. I noticed the same thing around the pump, I always take a file and clean up where the pump sets in. All the little channels need a good brushing and cleaning. No debris no grit etc... I'm getting carried away

  19. #19
    Senior Tuner kingtal0n's Avatar
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    Attachment 130365

    second gear is the default because notice both solenoids turn off. So you literally pull power away from the shift solenoids *cut the wires* and the trans will go to second gear.

    The only thing that changes in terms of fluid is the intermediate clutches come on. The sun gear is held by intermediate sprag outer race as part of sun gear shaft, and the output carrier pinion gears walk around the stationary sun gear (From the manual- I don't memorize this stuff). But these things wouldn't work at part throttle and then fail at WOT, they are mechanical and either work or not, broken or not. So part throttle shifts to second successfully kind of rules these mechanical aspects out I would think.

    This is the trans-go mod I will not make
    Attachment 130366

    It is also very important to use a thick intermediate snap ring