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Thread: LTG dropping boost and throttle regardless of pedal position.

  1. #1
    Tuner in Training
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    LTG closes throttle regardless of pedal position Driver demand issues

    So this car is a long story but our current setup is 2016 LTG to 6L80e transfer-case etc....
    We have had some success with the combo but we are looking for the last little details now and we have seemed to lose our way a little bit. We are running full E85 and not the sensor. The ECM isnt the original ECM that came with the motor but its is the correct OS. The pedal is the original that came with the engine (which is an 2014 ATS). I will attach the the tune file and most recent log. In this particular log we lost fuel rail psi randomly so we are replacing the DI pump right now. Any help would be much appreciated!
    Irls Car New Harness E85 Test 11.8.hpt

    E85 log 11.hpl

    IMG_75422.jpg
    Last edited by twistedtx; 1 Week Ago at 05:32 PM.

  2. #2
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    Hello.
    I have noticed in your file that all of the driver demand tables from 0-60 MPH are far too low in numbers. They are much less than even stock LTG numbers. Almost half. Perhaps this would be a good place to start on your search for throttle close.

  3. #3
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    i think it would help to record some extra turbo-related channels, like wastegate dutycycle, desired pressure ratio or boost , measured pressure ratio or boost.

    During your first WOT:
    I noticed your baro pressure goes down significantly during high airflow, obviously that's wrong. this is dependent on how you have your hardware configured, where your MAF is, air restriction differences between stock vs your setup, etc.
    I notice your max pressure ratio is 3.25, and at the peaks (ex 216kpa MAP / 69kpa baro = 3.13 pressure ratio) you're pretty close.. My guess is that you are hitting max pressure ratio because the baro signal is wrong. Since i can't find a way to fix the baro signal (best bet is probably to reconfigure the hardware setup, maybe, ), why don't you bump up the max pressure ratio to see if that helps (table 33491, Airflow >> Turbocharger >> Pressure Ratio Based).

    EDIT:
    During your second WOT:
    Due to your fuel pressure problem, it seems like you entered some safe mode that turned off the wastegate dutycycle, and are running on base boost only (understandable due to fueling problem).
    Your throttle cut during this second WOT seems to be some sort of engine overspeed protection to me, or maybe some trans overspeed? to troubleshoot this one i would record more torque request variables, and i think theres a variable that tells you the reason for the torque cut.
    Last edited by TurboCobalt; 6 Days Ago at 12:55 PM.

  4. #4
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    I have the fuel issue fixed now and things are better but still having a hard time getting the driver demand just right.

    Attachment 94412
    So the top circle is my MAF and the bottom right is the Tmap. Its may have a little bit more restriction than OEM on the air filter side but not much. I do not have a BARO sensor so I am a little confused but obviously the BARO has alot to do with the tune so IDK??? This isnt an OEM setup and I didnt have the option of installing a Baro sensor. I will bump the ratio and see what happens but do you have a recommendation as to what to do with the sensor setup to get it closer to an OEM reading?
    I have another log from today and i will attach it. I think i have found the limit of the DI pump which you can see at the 7:20 mark. I can work around that until we can get some upgrades installed. I will get a log tomorrow with more of the PIDs mentioned. Thanks for your help!!!!

    e85 log 16.hpl

    Irls Car E85 Test 20.hpt
    Last edited by twistedtx; 6 Days Ago at 09:11 PM.

  5. #5
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    Hello again. I see you have made some improve! Your actual torqu still seems to exceed you desire torque in some areas. This will close throttle on LTG. The fuel system is much limited also. You have a very high injector pulse width. I also run e85 in my LTG and have found I can no exceed 80% ethanal and 20 psi, leaving me around 320 torqu maximum. If you can cut ethanol to 50%, you will leave room for much more power, and get pulse with down closer to 5.5 ms. Hopefully this helps in some way!!

  6. #6
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    I am not running the alcohol sensor for simplicity sake because we want to eliminate every possible failure as much as possible. So we are running pure race E85 all the time(which may have been a mistake without replacing cams). i do appreciate the help always but as of now i want to continue down this road until i get the driver demand figured out atleast. the owner of this car is contemplating building a fully forged engine and at that point we will be able to increase the DI volume. I am working on the the couple spots now that went out of range on the DD and ill post the results later. I am still lost on the Baro reading fluctuating.

    When I modify my driver demand tables in the spots its like Pandora's box lol. so for the spots that are exceeding the requested torque I find that value and reduce it by say 10% and than smooth the tables accordingly? up to this point when I have done this it seems to make some other areas get out of control that I usually jump back several tunes and start over. I have had very little success in this area so any advice would again be greatly appreciated
    Last edited by twistedtx; 5 Days Ago at 04:37 PM.

  7. #7
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    twistedtx,

    so your table 33486, do not push this above 95, if you have a stock turbo , this table should be close to stock values.


    things are not really making sense to me in your latest datalog, boost solenoid control is 0%, but you're making over 200kpa MAP, that's not right. you're not running an aftermarket boost controller are you?
    The fuel pressure dropping off, that's odd too, i'm not convinced that you're running out of HPFP when you're only pushing 200 kpa MAP. are you sure your low pressure fuel pump is sufficient?

    Do you have a bunch of codes? There's something mechanically wrong, your first data log made more sense to me than this.

    EDIT: Your picture of your hardware setup didn't upload right, can you post some pictures of your setup again.
    the baro sensor should be inside the MAF sensor, where's your maf sensor? what are the odds that your air filter is clogged?
    Last edited by TurboCobalt; 1 Hour Ago at 09:14 PM.