Results 1 to 8 of 8

Thread: 4L80e wont wait till commanded RPM to shift WOT

  1. #1
    Senior Member
    Join Date
    Jun 2008
    Posts
    117

    Default 4L80e wont wait till commanded RPM to shift WOT

    Here is the tune and a log. See for your self

    Rudy_E85_95_0006.ctz

    Log_0264.efi

    It just keeps shifting at those specific RPMs, the runs in the log were on Tow/Haul (performance) mode. It seems to shift @ MPH but it wont reach the desired shift RPM @ WOT. My understanding is its supposed to meet both before it should command an upshift?? I really need it to match RPM instead of MPH because it's a turbo'd truck and sees different boost levels all the time, thus the torque converter will be seeing different slip RPM near the shift points at different boost levels and shift to early at low power levels and too late at high power levels... HELP!!
    -John

    1991 RCSB 2WD Sierra LQ4 swap, 220/224 112 cam, Twin VSR 6766 turbos
    4L80e w/shift kit, PY 3600, and 3.73 gears.
    22 PSI and E85, 4300# with driver. 9.7@138, 1.47 sixty
    :drivin:

  2. #2
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    4,936

    Default

    Does it do it in normal mode? Also, your part throttle shift tables are messed up in the Performance column. I think you were trying to force it to meet a higher MPG there, but Im amazed it would actually shift like that.

    Looking at the log, its shifting way after the MPH param is met (shifted 1->2 at 50mph, tables are set to 39MPH) so it seems the PCM thinks it's met both conditions. What does the cluster say during a shift, same as the log?

    Is this a swap truck or a factory PCM/truck combo? What gears, tire size, etc? Is the speedo section set correctly?

    Also, you're commanding stoich for PE. NOT GOOD. Especially since this is a boosted ride, B3647 and B3618 need to be changed. Im amazed you're not seeing any KR in that WOT pull, how are you tricking the PCM to get extra fuel? Its commanding 14.12:1 the whole time. Cant really tell without logging the WBO2 as well.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  3. #3
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Also, I think the Throttle Kickdown tables not being all 100% may be interfering.

  4. #4
    Senior Member
    Join Date
    Jun 2008
    Posts
    117

    Default

    Does it do it in normal mode? Also, your part throttle shift tables are messed up in the Performance column. I think you were trying to force it to meet a higher MPG there, but Im amazed it would actually shift like that.

    Did that for street/roll racing

    Looking at the log, its shifting way after the MPH param is met (shifted 1->2 at 50mph, tables are set to 39MPH) so it seems the PCM thinks it's met both conditions. What does the cluster say during a shift, same as the log?

    Yes, cluster and gauge both show 5500 ish

    Is this a swap truck or a factory PCM/truck combo? What gears, tire size, etc? Is the speedo section set correctly?

    Factory 5.3/4L60e truck, 4L80e segment swap. Yes all the speedo settings are correct.

    Also, you're commanding stoich for PE. NOT GOOD. Especially since this is a boosted ride, B3647 and B3618 need to be changed. Im amazed you're not seeing any KR in that WOT pull, how are you tricking the PCM to get extra fuel? Its commanding 14.12:1 the whole time. Cant really tell without logging the WBO2 as well.

    AFR's are good, hits high 12's from 11.5 map psi to 14, then gradually richens up to 11.5 @ 5psi boost. I prefer not to run PE, it's a speed density tune running just off of the MAPand O2's for crusing, as you can see in the VE table, the fuel goes up considerably after 11-13 map psi. Works REALLY well BTW.
    -John

    1991 RCSB 2WD Sierra LQ4 swap, 220/224 112 cam, Twin VSR 6766 turbos
    4L80e w/shift kit, PY 3600, and 3.73 gears.
    22 PSI and E85, 4300# with driver. 9.7@138, 1.47 sixty
    :drivin:

  5. #5
    Senior Member
    Join Date
    Jun 2008
    Posts
    117

    Default

    Whats weird is on his old setup the trans worked great! Just changed to a bigger turbo and redid his whole fuel system... Here's the old tune

    Rudy custom OS_7.tun
    -John

    1991 RCSB 2WD Sierra LQ4 swap, 220/224 112 cam, Twin VSR 6766 turbos
    4L80e w/shift kit, PY 3600, and 3.73 gears.
    22 PSI and E85, 4300# with driver. 9.7@138, 1.47 sixty
    :drivin:

  6. #6
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    4,936

    Default

    Interesting, so you basically turned it into a true SD tune using MAP v RPM? Huh, learn something new everyday. Hard to tell without a wideband input in that log, just based off the tune the red flag was going off in my head.

    Really weird about this though, especially when comparing those 2 tunes. What about starting again with the tune you just posted (Rudy custom OS_7) and copying all the fueling tables from the first tune into it? (Unless thats what you already did, in which case Im not sure.)
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  7. #7
    Senior Member
    Join Date
    Jun 2008
    Posts
    117

    Default

    Alright, so we went out playing with the truck last night and I'm still dumbfounded... if I adjust the WOT 1>2 & 2>3 shift speeds, it'll shift right where I set it to, but still the WOT shift at rpm settings act as if they're not there. Oh well, what I did is set the shift speeds a bit lower on Tow/Haul mode for higher boost settings so it'll still shift at the same rpm as the low boost when in normal mode.
    -John

    1991 RCSB 2WD Sierra LQ4 swap, 220/224 112 cam, Twin VSR 6766 turbos
    4L80e w/shift kit, PY 3600, and 3.73 gears.
    22 PSI and E85, 4300# with driver. 9.7@138, 1.47 sixty
    :drivin:

  8. #8
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Hi John, set the Throttle Kickdown tables to 100% in all cells, and re-test.

Similar Threads

  1. 4L80e swap, won't shift 1>2 WOT
    By LS1FREEK in forum 4speed RWD/FWD Transmission Tuning (incl T42)
    Replies: 16
    Last Post: March 22nd, 2013, 12:52 AM
  2. 4L80E no 2-3 shift at WOT
    By THEFERMANATOR in forum Gen III V8 Specific
    Replies: 2
    Last Post: November 9th, 2012, 01:19 PM
  3. 4L80E Will NOT SHIFT WOT
    By Mike@Vengeance in forum 4speed RWD/FWD Transmission Tuning (incl T42)
    Replies: 3
    Last Post: May 9th, 2012, 09:27 AM
  4. shift solenoids not working till commanded
    By SimpleManLance in forum Lounge
    Replies: 4
    Last Post: August 27th, 2011, 10:31 AM
  5. rpm cut off comes up before the 2>3 shift , wont shift
    By Eric in forum Gen III V8 Specific
    Replies: 7
    Last Post: June 6th, 2011, 09:58 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •