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Thread: 640 torque limit 512 g/s limit, how to bypass or scale? log and tune attached

  1. #1

    640 torque limit 512 g/s limit, how to bypass or scale? log and tune attached

    2007 twin turbo z06, methanol on 91, same car everyone has helped me with for the past 2 years, thank you.

    You will see in this WOT log, I am hitting some hard coded limit. the torque goes flat and will not pass 640 and the maf g/s goes flat at 512 g/s. I went back to look at older runs and I have never gone past that limit, it always goes flat at both of those spots. I ran into something like this when using the 1 bar map that limited at 114.5 kpa and had to get a 2 bar MAP sensor which fixed the issue.

    Do i need a different maf sensor?(my maf tables in the tune read past the frequency/limit it is showing)
    is there a table I can adjust(I did adjust the virtual torque tables but same result)?
    Do i have to scale tables down like i had to for my hard coded fuel injector limit?

    Thank you in advance. Afterwards I might also ask about that lean spike when i first get on the gas, but currently concentrated on the limits.

    640 torque 512 g per s max.hpl
    ve adj after cruising.hpt

  2. #2
    Senior Tuner
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    can change the [ecm 4042] from 800 to 8000 that will stop and tests for airflow, the maf only stops because ur maf table hasnt been adjusted above 512g/s with the 2 bar u can go to 1024g/s i think as ur hz keep going just its not tuned there, but maf is failed so u shouldnt be using it, see how that change goes

  3. #3
    Mine pegs out at 640 also. I thought I read on here you can adjust torque coefficient tables, but the ones describing this were using a Dyno and using real torque numbers to find the percentage it was off. IDK but there was talk of it may affect trans settings

  4. #4
    thank you very much for the replies, and I will try and adjust exactly what you said and take her for a ride tomorrow. you are correct, I do run 2 bar closed sd and do not need the maf at all, but I actually watch the maf and have the maf dialed in for 2 other reasons. Living in Denver i can switch the maf on when wanting to pass emissions, but two is silly and its for Horsepower calculations, i like the calculation against the torque tables(which I believe i have dialed in), but I also like calculating against the g/s for approximate horsepower. thank you again for the advice, applying changes now.

  5. #5
    I think I figured it out, I followed your advice and went to adjust those settings, only to find out it looks like a hard coded limit, please see pic attached, the airflow delta table maxes out at 4063 lb/hr which is 512 g/s. unless there is a patch or something I can do to bypass this, i do not believe my maf will accurately read above 512 g/s.

    thank you very much for the help, I am still curious though, if I raise ECM 4042 from 800 to 8000, I am guessing I will stop seeing the g/s reading all together, or are you saying if i change ECM 4042 to 8000 it will bypass the hard coded limit and read beyond the 512 g/s?

    4063 hard limit 512.PNG

  6. #6
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    setting that higher will stop any airflow error limp mode, u can still use dynamic airflow g/s it won't max out and use engine torque reading it won't max out either, some pids max out at 512 but u can go past without issues just log the other pids that keep reading i was well into the 700+g/s and over 1000 torque with the right pids

  7. #7
    Awesome my friend ty very much, will be testing out today.

  8. #8
    Ty very much, made the changes you recommended. I also started logging dynamic airflow which doesent hit a hard code limit like you recommended as well. The tune is pretty damn on now, putting out just under 700 hp at 5500 with 11 psi of boost at only 9 degrees of spark. Hoping for about 800-850 with 11 psi at 6400 and 13 degrees of spark. We will see, its almost there.

  9. #9
    Advanced Tuner eficalibrator's Avatar
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    512 g/s is the airflow limit, along with an 8.0 g/s fuel injector limit. There is a solution that involves scaling both of these by a known amount (along with all other mass-based ECU items and calculated torques) that will allow it work just fine above 512 g/s actual flow. We did this exact scaling exercise in one of our training videos (see link in sig) and even demonstrated how delivered fueling and spark were identical at part throttle after the change.

  10. #10
    Advanced Tuner jsllc's Avatar
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    So really what is the point of doing this? VVE runs out at 640 and we all know that a gen4 uses dynamic (for which we have no idea how it is calc'd)? As long as the trends are right it all works correctly anyway.

    Curious?
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  11. #11
    i personally do it for power estimations, but I don't use a vve, or a maf for fueling at all. I am 100 percent VE SD and just converted to full open loop(after burning an 02 wire lol). so why monitor dynamic airflow(when its disabled on my tune prior to 8000 rpms) and torque ratings, when they have no effect on my final fueling result, not just power estimations, but i can ensure my changes are taking true effects, for example when i use my boost controller to go from 6 to 10 lbs of boost, I want to see the map increase in KPA, the maf increase in frequency and the dynamic airflow increase as well. this lets me know all sensors are working correctly and I did truly increase my airflow and manifold pressure. the other reason i need dynamic airflow is because there is a horsepower calculation vs cc/min or g/s, all of these together allow me to triple check changes and get pretty accurate power estimates(generally within 20-30 hp). I also like to keep everything in tune so I can put my maf on when i want to go through emissions.
    I hope that answers your question, the easier answer is its probably unnecessary lol.

  12. #12
    Advanced Tuner jsllc's Avatar
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    Quote Originally Posted by Gpargament View Post
    i personally do it for power estimations, but I don't use a vve, or a maf for fueling at all. I am 100 percent VE SD and just converted to full open loop(after burning an 02 wire lol). so why monitor dynamic airflow(when its disabled on my tune prior to 8000 rpms) and torque ratings, when they have no effect on my final fueling result, not just power estimations, but i can ensure my changes are taking true effects, for example when i use my boost controller to go from 6 to 10 lbs of boost, I want to see the map increase in KPA, the maf increase in frequency and the dynamic airflow increase as well. this lets me know all sensors are working correctly and I did truly increase my airflow and manifold pressure. the other reason i need dynamic airflow is because there is a horsepower calculation vs cc/min or g/s, all of these together allow me to triple check changes and get pretty accurate power estimates(generally within 20-30 hp). I also like to keep everything in tune so I can put my maf on when i want to go through emissions.
    I hope that answers your question, the easier answer is its probably unnecessary lol.

    Question was why scale maf and fuel. Unless it is a heavily patched OS none of them are directly used. MAF ends @ 512 g/sec and VVE @ 655.35 g/sec. Yet my car hits 812 g/sec dynamic and dynamic is what the ECM uses 100% of the time.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  13. #13
    Thank you for the reply, not sure how else to answer your question. Also if you look at my tune, my dynamic airflow is disabled until 8k rpms, as in i don't use dynamic air for fueling, I strictly use my ve table. Again i use dynamic airflow for estimated hp calculations.

  14. #14
    Advanced Tuner jsllc's Avatar
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    Where an understanding makes all the difference. If you use an e38 or e67 you cannot use anything other than dynamic. It is the only thing the ECM uses for fueling. Better than that you can NEVER adjust it directly. You can only adjust modifiers. MAF, VVE in an unpatched OS are just modifiers. It is a formula in the ECM that we do not know all of the modifiers or the logic that guides it. In a patched OS we also have no idea. We did not write the code and a dare anyone on this forum (except maybe a HPT software engineer) to tell us with 100% certainty what the logic is behind at patched OS or Stock code.

    If you step back and think about it. If the MAF logging ends @ 512 g/sec why does the car keep running???

    Same holds true for VVE if the logging or PID info VVE ends @ 655.35 g/sec what magic extends that???

    The only value that goes beyond this is Dynamic. It has at least 50 modifiers that I know of. I am sure there are many more we do not see or understand.
    Last edited by jsllc; 4 Weeks Ago at 12:58 PM.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  15. #15
    let me rephrase, i should have been clearer. I do not use dynamic or maf for any type of fueling adjustments, i only use my ve table for fuel alterations, i only monitor dynamic because i like it for power calculations. I was monitoring maf for the power calculations before going turbo, but it topped out at 512 g/s, causing my torque to top out at 640, now that I monitor dynamic, i can use it for power calculations beyond the 512 g/s and 640 torque.

    *I do tune the low maf frequency, so I can turn it on for emissions, but that is only once every two years.