Results 1 to 8 of 8

Thread: 4L80E Line Pressure

  1. #1
    Junior Member
    Join Date
    Jun 2012
    Posts
    39

    Default 4L80E Line Pressure

    Hello All!
    I am still a bit of a Noob when it comes to the programming aspect of performance, so I totally need some help from someone with more knowledge. I am posting this in the transmission and forced induction section for two different issues.

    To start, this is a turbo (S366) third gen 5.3 with a GT2-3 cam and 2000 LS1B w/ COS 5. Its in a heavy 4x4 with a fresh SRTA 4L80E 2K stall and 3.73's

    The question I have in this thread, is do I have the line pressure correct for my application? The trans builder said to have all the line pressure in by 25% throttle or so. I'm sure there are a number of things wrong with this tune, including the shift points, but I am doing it one at a tome right now. Could someone please tell me if I'm going to burn up this trans? Especially when I begin to tow. (4-5K lbs)

    THANK YOU!!
    Attached Files Attached Files

  2. #2
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    The shift base pressure tables (D0701,2,3) are used during shifts...

    PCM calculates the base running (non-shift) pressure based on calculated engine torque is calculated from VE/MAF... so if you got VE and MAF correct (not under-reporting) then base running pressure will be good.

    I generally do this:
    - set D0701,2,3 to start sloping up from (0,0) and to reach 96 psi by 354-399 ftlb.
    - set D1108,9,10 to 0.20-0.25s.
    - set D0801,2,3 to control shift feel (I aim for a nice firm shift upto 33% throttle, and for solid wheel chirp above 50% throttle).

    I also do this:
    - set D0960,1,2 to zero everywhere (let the VSS upshift/downshift tables control shifting).
    - set D2904 to 99-100%.
    - set D2903 to 90-95% (you may want to adjust this down if it's too jerky).

    Some people also do this (I don't always get changes with this):
    - set D2901 to some higher value.

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

    Default

    Also log GM.TFMPRS and GM.TCCMODE.

  4. #4
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    I see a delay of 1 second from PE enable to PE actually kicking in...

    you need to set B3609 to zero.

  5. #5
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    You should use more fuel when PE kicks in, set B3618 to 1.25 EQR throughout, to be safe.

    You should start ramping up B3647 earlier, from say MAP 80-85 kPa (which is quite a significant load).

  6. #6
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Also take care of this:

    make each WOT downshift MPH below their corresponding WOT upshift MPH...

    for example: each of D0925, D0930, D0935 mph should be below its corresponding/respective D0910, D0915, D0920 mph

    ( and same for all the other corresponding WOT shift pairs )

  7. #7
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Quote Originally Posted by joecar View Post
    Also log GM.TFMPRS and GM.TCCMODE.
    Log GM.TFMPRS...

    and also connect a 300 psi pressure gauge to the line tap on the side of the trans case, and do a few test drives while observing the gauge, this will tell you if line pressure is good (line pressure should go up easily with throttle, at WOT you want to see something like 200-230 psi)... your trans builder should have told you to do this.
    Last edited by joecar; September 11th, 2016 at 11:32 PM.

  8. #8
    Junior Member
    Join Date
    Jun 2012
    Posts
    39

    Default

    Joe! Thank you very much! I am making changes tonight and will try them tomorrow.

Similar Threads

  1. 4l80e swap, converter making noise at low load? Line pressure?
    By jay_rich in forum Gen III V8 Specific
    Replies: 0
    Last Post: June 22nd, 2015, 03:58 AM
  2. 4L80E with Trans Brake, no reverse, line pressure?
    By tdmkr496 in forum 4speed RWD/FWD Transmission Tuning (incl T42)
    Replies: 3
    Last Post: September 20th, 2014, 05:27 AM
  3. line pressure in efilive
    By Cool28 in forum 4speed RWD/FWD Transmission Tuning (incl T42)
    Replies: 3
    Last Post: February 12th, 2012, 06:20 AM
  4. 4L80E line pressure
    By pullincrazy88 in forum 4speed RWD/FWD Transmission Tuning (incl T42)
    Replies: 2
    Last Post: November 17th, 2010, 12:56 PM
  5. line pressure
    By dezzi in forum Allison 5 & 6 Speed
    Replies: 1
    Last Post: January 18th, 2010, 01:59 AM

Tags for this Thread

Posting Permissions

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