Page 1 of 2 12 LastLast
Results 1 to 20 of 39

Thread: Max number of steps allowed for IAC motor

  1. #1
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208

    Max number of steps allowed for IAC motor

    Hey guys,

    Is this parameter exposed in HPT? I did the 24X 0411 swap onto my '96 LT1 and would like to change this number from the LS1 365 to the LT1 160.

    Thanks,
    Jason

  2. #2
    Senior Tuner Ben Charles's Avatar
    Join Date
    Aug 2009
    Location
    Calibrating
    Posts
    3,371
    My LT1 uses up to 310 without issues.

    Email Tunes, [email protected]
    96 TA Blown/Stroked, 4L80E/Fab 9
    15 C7 A8 H/C 2.3 Blower/PI
    14 Gen 5 Viper
    Custom Mid Engine chassis, AKA GalBen C

  3. #3
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    Cool. Thanks Ben. I assume that you're actually seeing an increase in airflow above the 160 step number?

    Jason

  4. #4
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    I tried to control the IAC with the bi directional part of the scanner, to see if there is in fact an increase in airflow above 160. BUT, the scanner only allows you to command 127 counts. WHY????

    Jason

  5. #5
    Senior Tuner
    Join Date
    Sep 2008
    Posts
    1,668
    Bidirectional controls can only allow so much, it's not HPTuners, it's GM.
    2010 Camaro SS M6. Stock Bottom End, Heads/Cam/Intake/Headers/Exhaust.
    2005 Silverado RCSB. Forged 370 LQ9/Borg-Forced Inductions T6 S484/Jake's Stage 4 4L80E with D3 Brake/4WD.
    2023 Durango Hellcat

  6. #6
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    Thanks Mike. Seems like a leftover from some earlier PCM...

    Jason

  7. #7
    Senior Tuner
    Join Date
    Sep 2008
    Posts
    1,668
    No, seems like binary math...0 through 127 is 128...2*2*2*2*2*2*2=128.
    2010 Camaro SS M6. Stock Bottom End, Heads/Cam/Intake/Headers/Exhaust.
    2005 Silverado RCSB. Forged 370 LQ9/Borg-Forced Inductions T6 S484/Jake's Stage 4 4L80E with D3 Brake/4WD.
    2023 Durango Hellcat

  8. #8
    Senior Tuner mowton's Avatar
    Join Date
    Mar 2007
    Location
    Florida
    Posts
    3,773
    Quote Originally Posted by MikeOD View Post
    No, seems like binary math...0 through 127 is 128...2*2*2*2*2*2*2=128.
    or is it like Chris' signature....."I count sheep in Hex" :-) 1,2,4,8,16,32,64 = 127 (only 7 bits though???????)...parity, +/- etc for 8th bit? note == Zero is a real number in this system.

    Ed M
    Last edited by mowton; 12-02-2014 at 08:24 AM.
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

    ERM Performance Tuning -- Interactive Learning ..from tuning software training to custom tunes
    HP Tuners Dealer- VCM Suite (free 2hr training session with purchase), credits and new Version 2.0 turtorial available
    http://www.ermperformancetuning.com
    http://www.facebook.com/ERMPerformanceTuning

    [email protected]

  9. #9
    Senior Tuner
    Join Date
    Sep 2008
    Posts
    1,668
    Quote Originally Posted by mowton View Post
    or is it like Chris' signature....."I count sheep in Hex" :-) 1,2,4,8,16,32,64 = 127 (only 7 bits though???????)...parity, +/- etc for 8th bit? note == Zero is a real number in this system.

    Ed M
    6 of one...half a dozen of the other ...I guess I should have said "seems like a computer" not "seems like binary math" LOL
    Last edited by MikeOD; 12-02-2014 at 09:13 AM.
    2010 Camaro SS M6. Stock Bottom End, Heads/Cam/Intake/Headers/Exhaust.
    2005 Silverado RCSB. Forged 370 LQ9/Borg-Forced Inductions T6 S484/Jake's Stage 4 4L80E with D3 Brake/4WD.
    2023 Durango Hellcat

  10. #10
    Senior Tuner mowton's Avatar
    Join Date
    Mar 2007
    Location
    Florida
    Posts
    3,773
    More than 1 way to skin the cat Mike :-) Happy Holidays....
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

    ERM Performance Tuning -- Interactive Learning ..from tuning software training to custom tunes
    HP Tuners Dealer- VCM Suite (free 2hr training session with purchase), credits and new Version 2.0 turtorial available
    http://www.ermperformancetuning.com
    http://www.facebook.com/ERMPerformanceTuning

    [email protected]

  11. #11
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    Good point guys. Being a MECHANICAL engineer, I don't usually think in binary or hex....

    Any help on how I can figure out how many steps the LT1 IAC hardware actually will execute?

    Thanks,
    Jason

  12. #12
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    Was just thinking about this again on the way home... I think I figured out how to test the LT1 style IAC for max counts. Create a tune that requests idle to increase from 2500-4000 with increasing temp. Get the engine nice and warm on the "normal" tune. Then upload the test tune. Watch the IAC counts to see where the RPM stop increasing with commanded IAC steps.

    Will try this tomorrow out in the middle of no where so I don't have my neighbors calling the cops

    Jason

  13. #13
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    Tried my idea this morning. No dice. PCM will only command up to 1200 rpm idle. HPT will let you put 8000 in the table but the sets anything over 1200 to 1200. So thinking I need to try something with the throttle follower / cracker tables to get the airflow up since I can't raise the idle.

    Jason

  14. #14
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    OK, finally got the smoking gun. See the attached log files. Make sure you are looking at the following:

    MAF
    idle base sum airflow
    IAC pos
    IAC desired pos


    IAC log 001.hpl
    IAC log 002.hpl
    Last edited by JasonS5555; 01-30-2015 at 03:20 PM.

  15. #15
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    IAC Log 001

    I used the idle air table to add air with engine temp. So the IAC gradually goes up and the actual MAF airflow does not.

    I also used the throttle cracker to add a ton of air. So you can see when I blip the throttle, the IAC goes to 310. The airflow does not increase, and as the IAC decays, it still is around 1.8 lb/min max which is about what you get with IAC = 200.

    IAC log 002

    Here I manually turn on the fans so the engine temp drops and the desired idle air flow increases as the engine temp goes down. The MAF reading goes up, but only until about 200 IAC counts.

    So from these two logs, it appears that the L98/LT1 style IAC does not go to 310.

    How can I request access to this parameter with HP Tuner? I can see it in TunerPRO.

    Jason
    Last edited by JasonS5555; 01-30-2015 at 03:28 PM.

  16. #16
    Senior Tuner
    Join Date
    Sep 2008
    Posts
    1,668
    Find a file in Tunerpro that you can change it in (I think the only definition that will work is a 2001 os). Change it and nothing else, and send support both files explaining what you did and asking them for access to it in your is.

  17. #17
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    I couldn't find any contact info for support. So I started a thread here:

    http://www.hptuners.com/forum/showth...-2001-0411-PCM

    Is that the correct process?

    Those of you with LT1 24X conversions may want to express your support.

    Thanks,
    Jason

  18. #18
    Senior Tuner
    Join Date
    Sep 2008
    Posts
    1,668
    2010 Camaro SS M6. Stock Bottom End, Heads/Cam/Intake/Headers/Exhaust.
    2005 Silverado RCSB. Forged 370 LQ9/Borg-Forced Inductions T6 S484/Jake's Stage 4 4L80E with D3 Brake/4WD.
    2023 Durango Hellcat

  19. #19
    Advanced Tuner
    Join Date
    Apr 2009
    Posts
    613
    Sounds to me like the iac port in your tb is limited to x airflow. The other thing is why do you need that high of iac count anyway?

  20. #20
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    Will do. Thanks Mike.

    Flame, the LT1 TB is completely different. Flow volume and IAC motor. I just want to be able to set the max steps value in the PCM so it doesn't keep trying add steps that just don't happen.

    I'm still trying to figure out how to re-map the flow volume per IAC step:

    http://www.hptuners.com/forum/showth...uning-IAC-area

    Thanks,
    Jason