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Thread: 2005 GTO E40 Throttle Position at Idle and Start-Up

  1. #1
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    2005 GTO E40 Throttle Position at Idle and Start-Up

    Edit: I uploaded the Tune and a log file. I don't have a good log file of the idle where the TP drops as the AP is pressed. I'll record one tomorrow morning. Don't laugh at my tune. I'm wearing my "newbie" name tag proudly.


    1st Issue:

    When I press the throttle slightly (2-3% Pedal Position) the Commanded Throttle Position at idle goes from a steady ~14% down to ~11%. What this does is make it a pain in the ass to park the car or leave a stop light where you only need a small amount of throttle before engaging the clutch. It kind of makes the gas pedal into an on/off switch because too little and it will stall, too much and I'm at 2K. It looks like I'm a 15 year old learning how to drive a stick for the first time.

    I've played with the Idle Airflow tables up and down, Final Airflow Tables up and down, etc.


    2nd Issue:

    I need to increase the throttle opening at start up. I've played around with the same tables as above and can't seem to find a "happy place". When cranking the Commanded Throttle Position is usually around ~10% and it won't start without pressing the gas pedal to around 18% or more. Is there a table that I can increase the throttle during cranking only without jacking with my idle airflow? What am I missing here.



    Thanks for any help,
    Cole
    Attached Files Attached Files
    Last edited by ColeGTO; 03-29-2018 at 01:18 AM. Reason: Added tune and log files
    1967 Camaro N/A SBC (10.19 @ 136 mph)
    2005 GTO PBM/Red/M6 - 6.2 w/ LSX-LS7 heads & LSX454 cam / Kooks 1.875" / Exh / Whiteline Bushings / etc.
    http://cole.balster.googlepages.com/home

  2. #2
    Senior Tuner Lakegoat's Avatar
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    Sounds like you need to tune for the heads and cam. Post up the tune and a log of the problem. Why would you want to change the cranking airflow if the problem is taking off from a stop?
    2000 Camaro SS 2015 L83 port injected, Whipple 3.0, 4L80E, 8.8 Ford
    2013 Silverado 5.3, 6L80k 8.8

  3. #3
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    Quote Originally Posted by Lakegoat View Post
    Sounds like you need to tune for the heads and cam. Post up the tune and a log of the problem. Why would you want to change the cranking airflow if the problem is taking off from a stop?
    I have two problems, one leaving a stop and the other at startup.

    I will post up the tune and log when I get home tonight. I have tuned quite a bit already. I'm in SD mode finishing the VE table before I start working on the MAF table. I'm definately still "new" to tuning, but I've managed to get it running pretty good. This cam with 21 degrees of overlap has been a pain in the butt to tune idle and drivability though.


    Thanks for looking though.
    1967 Camaro N/A SBC (10.19 @ 136 mph)
    2005 GTO PBM/Red/M6 - 6.2 w/ LSX-LS7 heads & LSX454 cam / Kooks 1.875" / Exh / Whiteline Bushings / etc.
    http://cole.balster.googlepages.com/home

  4. #4
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    I updated the original post with tune and log files. Feel free to look over the whole tune and tell me how far in left field I really am.

    Thanks for any help.
    Last edited by ColeGTO; 03-29-2018 at 01:19 AM.
    1967 Camaro N/A SBC (10.19 @ 136 mph)
    2005 GTO PBM/Red/M6 - 6.2 w/ LSX-LS7 heads & LSX454 cam / Kooks 1.875" / Exh / Whiteline Bushings / etc.
    http://cole.balster.googlepages.com/home

  5. #5
    Senior Tuner Lakegoat's Avatar
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    What throttle body and intake do you have? If you have a larger than stock tb, the ETC scalar is still stock. If you don't have cats, I would disable post O2 test and Cat test in engine diag. With a 21 degree overlap, I would guess that you can run some more idle timing. Here is my cranking airflow and spark tables. Maybe give that a shot and see what happens. I would add about 15% to the 650rpm to 1600 rpm columns in your base running airflow table. That's pretty low # for a big cam and 950 rpm.
    Attached Images Attached Images
    Last edited by Lakegoat; 03-29-2018 at 02:44 PM.
    2000 Camaro SS 2015 L83 port injected, Whipple 3.0, 4L80E, 8.8 Ford
    2013 Silverado 5.3, 6L80k 8.8

  6. #6
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    Thanks for the help. I'll give your tables a shot and let you know.

    My car has a "ported" stock 90mm TB and K&N Hot Air Intake, so I left the ETC scalar alone.

    I have long tubes and catted mids. I need the rear O2's and test to pass CA emissions.

    What do you think of my VE table so far? It has a "different" shape to it compared to a few others I have seen, but i think the big cam is what is really driving the dip in the middle. I'm still tweaking it a little here and there. I haven't done much MAF tuning yet either. We'll see how that goes.




    Thanks again,
    Cole
    1967 Camaro N/A SBC (10.19 @ 136 mph)
    2005 GTO PBM/Red/M6 - 6.2 w/ LSX-LS7 heads & LSX454 cam / Kooks 1.875" / Exh / Whiteline Bushings / etc.
    http://cole.balster.googlepages.com/home

  7. #7
    Senior Tuner Lakegoat's Avatar
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    VE shape looks pretty good to me, everyone is different. Here is mine
    Attached Images Attached Images
    2000 Camaro SS 2015 L83 port injected, Whipple 3.0, 4L80E, 8.8 Ford
    2013 Silverado 5.3, 6L80k 8.8

  8. #8
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    try copy your idle and coast down values into main tables from 0-1400rpm and 0.08-0.32 and blend it. try to see if the addition of timing is what's causing your stumble.

    however of throttle stumble generally indicates lean or a vacuum leak