Results 1 to 14 of 14

Thread: 4L80e swap WOT not shifting when expected, part throttle OK

  1. #1
    Tuner
    Join Date
    Mar 2008
    Location
    Waukesha, WI
    Posts
    95

    4L80e swap WOT not shifting when expected, part throttle OK

    I'm hoping someone has some insight here. The truck is a TBSS with twin turbos and a 4L80e swap. Truck runs fine and shifts most of the time just fine, but the WOT 1-2 will often hit the limiter. I've set some very conservative values for WOT shifts and it still doesn't end up shifting either close to, or over, the engine limit. I've searched the forum and verified everything I can find, and I'm at a loss here. Tune and scans attached.

    Tune - Attachment 93085
    Scan 1 - Attachment 93086
    Scan 2 - Attachment 93087
    2007 Trailblazer SS - LS2 | S256sx + S256sx | E85 | Built 4L80-E
    1991 Olds Cutlass Supreme International Sedan - L67 | GT35R | E85 | Built 4T65-E HD | NO2

  2. #2
    Advanced Tuner Lakegoat's Avatar
    Join Date
    Jul 2012
    Location
    Florida
    Posts
    796
    Do you really want to shift at 5400rpm? At 5400rpm in first, you are at about 41mph. Your WOT shift point is 25mph. Probably too wide a spread for the computer. Try about 5mph less (36). Also in your shift normal table, you call for 40mph---probably too high.
    2005 GTO, TrickFlow 225, Magnuson 2300, 4L80, 4 link 8.8
    2013 Silverado 5.3, 6L80

  3. #3
    Tuner
    Join Date
    Mar 2008
    Location
    Waukesha, WI
    Posts
    95
    That tune is essentially a 2007 Suburban, which I applied after my original tune wasn't working. My original tune had the values closer, and it's the one that is in the truck now. It's attached. Either way, same thing - WOT won't shift. If I do anything other than WOT, it will shift fine - even a few percent less than WOT.

    My fear is that there is something not so obvious at play here.

    Backstory - The truck was running a 2008 PCM / TCM tune and shifting just fine, even at WOT before I put the turbos on it. After I put the turbos on it, I couldn't tune it on the street and had a local tuner that had dyno access go through it and fix the PCM tune (didn't touch the TCM). He ended up writing a 2006 PCM/TCM tune into it, and even though the TCM calibration was copied as it was with the 2008 calibration, it won't shift at WOT now. I compared both the 2008 and 2006 TCM tunes, and they match.
    Attached Files Attached Files
    2007 Trailblazer SS - LS2 | S256sx + S256sx | E85 | Built 4L80-E
    1991 Olds Cutlass Supreme International Sedan - L67 | GT35R | E85 | Built 4T65-E HD | NO2

  4. #4
    Advanced Tuner
    Join Date
    Apr 2017
    Location
    Meridian MS
    Posts
    418
    Put both Abuse Mode tables back to stock, no need to change those unless you're planning to do some cool neutral drops at WOT.

  5. #5
    Tuner in Training
    Join Date
    Oct 2018
    Posts
    35
    I have the same issue in my 02 Tahoe, although it is a P01 gen 3 ECU. 4l80e swap worked fine until I installed a turbo and 3.73>>> 4.56 rear gear swap. After that it would not shift out of first at WOT, part throttle worked fine. Researched, and did a lot of suggestions with torque management, WOT Speed, WOT RPM, etc, and nothing worked. In the end I disabled WOT shifts through a WOT Enable table. I don't see that table in your ECU tho. I would try 0ing out all the full throttle rpm and speed tables. And then use the part throttle 100% column to tell it when to shift. TAKE THIS WITH A GRAIN OF SALT, GEN 4 MAY OPERATE COMPLETELY DIFFERENT IN THIS REGARD.

  6. #6
    Tuner
    Join Date
    Mar 2008
    Location
    Waukesha, WI
    Posts
    95
    Ok, so I did a couple of things.

    1. Put those two abuse tables back to stock
    2. Raised the last two columns of the part-throttle shift speeds to above the WOT shift speeds (similar to the stock tune, and only because I noticed it)
    3. Lowered the WOT 1-2 shift speed by 5% (reduced the 2-1 shift in a similar fashion)

    The truck shifts at WOT now, although not exactly where I'd like it to...but I can adjust for that now that it actually shifts. My question is - without backing each of these changes out, which one is most likely the fix? Does the part-throttle 100% column matter when there is a WOT table already?

    Latest tune and scan attached (I know I need to reconfig the scanner for transmission scanning)
    Attached Files Attached Files
    2007 Trailblazer SS - LS2 | S256sx + S256sx | E85 | Built 4L80-E
    1991 Olds Cutlass Supreme International Sedan - L67 | GT35R | E85 | Built 4T65-E HD | NO2

  7. #7
    If I remember correctly, the ecm has to have both of those tables satisfied to shift. So as long as you are going the min mph, it will shift at the commanded rpm, or vice versa. Make sure you have correct rear end ratio, and tire size in also. I usually match the part throttle Wot speeds with the Wot shift speed tables.
    Last edited by h2.4; 4 Weeks Ago at 10:07 AM.

  8. #8
    You need to add way more channels to get an idea of what is going on overall with tuning this vehicle. Not only the transmission channels either.... and a bit more work on setting stuff up and dialing fueling in, before doing Wot pulls.
    Last edited by h2.4; 4 Weeks Ago at 10:25 AM.

  9. #9
    Tuner
    Join Date
    Mar 2008
    Location
    Waukesha, WI
    Posts
    95
    The engine side of things was recently done by a local tuner, and should be a SD 2-bar tune. It put down 580 but it has a misfire on high RPM. Turns out the plug wires were burnt. After replacing those, it's smooth as can be. I haven't looked at the engine tune as much...does it have issues I need to address?

  10. #10
    Quote Originally Posted by eclipse5302 View Post
    The engine side of things was recently done by a local tuner, and should be a SD 2-bar tune. It put down 580 but it has a misfire on high RPM. Turns out the plug wires were burnt. After replacing those, it's smooth as can be. I haven't looked at the engine tune as much...does it have issues I need to address?
    your fuel trims are pretty far out, 18% in some areas. Maybe they spent majority of time in the Wot range on the dyno.

  11. #11
    Advanced Tuner Lakegoat's Avatar
    Join Date
    Jul 2012
    Location
    Florida
    Posts
    796
    The 2-6-1 trans tune that you posted is nothing like the original tune in the first post. According to your scan, you want it to shift at 55 mph---which it is. Your rev limiter is set at 6700 and you are shifting at 6600+. Your wot shift rpm is set 6000 for the 1-2 shift but that doesn't match your mph. I don't know why you maxed out the A and B tables . Don't have just one cell at the end determine your shift point. Use at least two. When you get your shift table where you want it, make them all the same. If you want to shift at 6000rpm, that is 47mph on your scan. Make your wot speed 42mph and start there and see where that puts you. Should be close.
    Last edited by Lakegoat; 3 Weeks Ago at 05:40 PM.
    2005 GTO, TrickFlow 225, Magnuson 2300, 4L80, 4 link 8.8
    2013 Silverado 5.3, 6L80

  12. #12
    Tuner
    Join Date
    Mar 2008
    Location
    Waukesha, WI
    Posts
    95
    Correct, it's the tune I had in the truck originally, which did shift at WOT where I wanted it to. When that tune wasn't shifting correctly after the turbos, I started messing with things. When those things weren't working, I put it back and followed your/other recommendations - Put the abuse tables back, put the WOT speeds a little lower than where they would be with the shifting RPM, and put the last column (100% TPS) part-throttle shift speeds a little higher. I'm not sure which one actually resolved the issue.

    It's shifting when it should most of the time without hitting the limiter. Sometimes it still hits the limiter when shifting, but usually when the tires are spinning good. Looking at the current scan (first WOT pull) why does it wait until 6200RPM and 49MPH to command the shift? That, combined with the time it takes to shift, can easily reach 6700 RPM. WOT tables are set for 45 MPH and 5800 RPM.

    Also, since I can't easily test a 2-3 WOT shift on the street, do my 2-3 RPM/MPH look close enough?

    version 2-10.hpt
    scan-2-10-3.hpl
    Last edited by eclipse5302; 3 Weeks Ago at 06:46 PM.
    2007 Trailblazer SS - LS2 | S256sx + S256sx | E85 | Built 4L80-E
    1991 Olds Cutlass Supreme International Sedan - L67 | GT35R | E85 | Built 4T65-E HD | NO2

  13. #13
    Advanced Tuner Lakegoat's Avatar
    Join Date
    Jul 2012
    Location
    Florida
    Posts
    796
    At 5800 rpm, you are already at 46mph. You need to make it 41mph. The mph has to be made, then the rpm has to be made to shift. Look at the screenshot. Make your Normal, A and B tables the same. Make your WOT tables the same to match the Normal,A,B tables. This is for 1st gear as I don't have a way to check the other gears. Dragstrip is best.
    Just changing the shift rpm is not going to solve your problem. You have to choose an rpm where you want it to shift and then figure the mph minus 5mph.
    Attached Images Attached Images
    Last edited by Lakegoat; 3 Weeks Ago at 12:46 PM.
    2005 GTO, TrickFlow 225, Magnuson 2300, 4L80, 4 link 8.8
    2013 Silverado 5.3, 6L80

  14. #14
    Tuner
    Join Date
    Mar 2008
    Location
    Waukesha, WI
    Posts
    95
    Ok, I'll give it a shot. Thanks!
    2007 Trailblazer SS - LS2 | S256sx + S256sx | E85 | Built 4L80-E
    1991 Olds Cutlass Supreme International Sedan - L67 | GT35R | E85 | Built 4T65-E HD | NO2