Results 1 to 3 of 3

Thread: E67 Will Not Obey Commanded Idle! (files attached)

  1. #1
    Junior Member
    Join Date
    Jan 2014
    Posts
    31

    Question GMPP LSX376-480 / 525 Idle RPM High - Unable to Change

    *EDIT* Changed title once I realized what was going on. The tune/OS 12638778 in the GMPP E67 controllers have a known issue of not being able to get the idle rpm to go below 875, regardless of ANY of the parameters we have access to (EFI live nor HPT) I found a couple threads of work-arounds on HPT forum but wondering if anyone here with EFI Live has successfully solved this problem? Is there an earlier version of 12638778 out there that does not have this mystery idle rpm limit?

    hopefully these reference links are ok...
    Post #9 in this first one sounds promising: https://forum.hptuners.com/showthrea...igh-Idle-Issue
    https://forum.hptuners.com/showthrea...e-stuck-850rpm
    https://forum.hptuners.com/showthrea...-ls3-high-idle

    Original post:

    Working on a customers LSX376-525 with 2.9l Whipple and something is preventing the throttle blade from trying to close to drop idle speed to the commanded value. Timing is not being pulled to try to help either (real-time values are matching B5104 base idle spark table). It either doesn't know its 100+rpm too high, or it just doesn't care lol.
    I suspected B1829 Minimum Idle Airflow, but cutting the values around the idle range in half didn't change anything. Any idea what I am missing? Thanks!
    Log and tune files:
    RevT min airflow TEST.ctz
    idle park.efi
    Last edited by chevyspence; January 13th, 2021 at 12:52 PM. Reason: found root cause of issue, hidden parameters inaccessible

  2. #2
    Junior Member
    Join Date
    Jan 2014
    Posts
    31

    Lightbulb

    OK, so.... potential solution! Start with tune file "2010 GMPP E-ROD" (12638778) and update all values/tables with your tune file parameters "RevS idle Checkpoint" (12638778) in my case, and viola; no more hidden idle RPM minimum limit!!!
    Now, only two small details I'm not familiar with... How does one go about transferring all the values from one .tun file to another of the same OS? Surely there has to be some way other than manually copying and pasting thousands of values?!? Secondly, after renaming that updated "2010 GMPP E-ROD" file something like "RevT idle min fixed" would there be any issue with writing this into the PCM? Standard re-flash or "full" flash?
    Never thought lowering the idle 100rpm was going to be the most difficult part of this tuning job

    2010 GMPP E-ROD Crate Motor Manual LS3 6.2 Litre (12638778).tun
    Click image for larger version. 

Name:	2010 GMPP E-Rod.PNG 
Views:	143 
Size:	166.2 KB 
ID:	23638
    Click image for larger version. 

Name:	Rev S - Idle checkpoint.PNG 
Views:	138 
Size:	165.6 KB 
ID:	23639
    RevS idle checkpoint.ctz

  3. #3
    Junior Member
    Join Date
    Jan 2014
    Posts
    31

    Default

    Update, so I did confirm that the work-around did in fact work! would really be nice to simply be able to see that hidden idle rpm value/table in the lsx376-480/525 tune files, but in the meantime, if anyone else is running into this issue:
    1) Open the 2010 GMPP E-Rod tune file (attached to my post above or download from tune file depot)
    2) Load comparison file (your tune file you want to run, with same 12638778 os of course)
    3) Edit > Create Script , name it, and save
    4) Edit > Run Script, open it, and run
    5) Transfer your VIN over (copy and paste it into the VIN field in the "calibration" window
    6) "Program PCM with currently loaded calibration"

Similar Threads

  1. Need an opinion and help on the pressures/ slip of new tranny. Files attached
    By mjmenke1 in forum 4speed RWD/FWD Transmission Tuning (incl T42)
    Replies: 8
    Last Post: May 11th, 2017, 11:58 AM
  2. Replies: 13
    Last Post: February 19th, 2014, 05:03 PM
  3. Rich at idle OLSD??? Tune attached, any help?
    By T&A Custom Rides in forum Gen III V8 Specific
    Replies: 8
    Last Post: February 9th, 2012, 04:05 PM
  4. Problem with my Head/Cam 98 LS1 camaro - files attached
    By blackflag in forum Gen III V8 Specific
    Replies: 157
    Last Post: May 10th, 2011, 04:27 PM
  5. BIG Auto VE problem - Tune files attached
    By Kevin Doe in forum General (Petrol, Gas, Ethanol)
    Replies: 15
    Last Post: October 14th, 2007, 01:57 PM

Posting Permissions

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