^^^ If you have too many channels/too much math running at the same time, it will do that. On mine, only MAF WB shows in real time. What I do is finish my log, save, close the VCM, re-open, and load the log, and everything shows up - as in, log your shit and don't pay attention to things not showing, they will show once you save and re-open. Hope that makes sense.
Last edited by mememe123; 12-28-2022 at 08:07 AM.
^^^ +1 to to meme's comment. That's a good tip.
This right here is not just the key to HP tuners but is literally the key to the internet and software as a whole. It should be listed as the first rule of life.Originally Posted by blindsquirrel
Anyone have experience implementing this math on Gen V's? Read through this thread several times but think I'm missing something...
When I run the formula manually and in Excel using various points in a log I'm seeing unexpected results, like around -20% when driving at a steady state and idling, meanwhile my lambda is almost bang on the commanded 1.000, or real close. The formula I'm using is:
(([16.71]*(1+(([50127.238]-[68.238])/[68.238]))-([50070.56]/60*3*[11.92]*[2312]/[2126.240]))/([50070.56]/60*3*[11.92]*[2312]/[2126.240]))*100
16.71 = MAF in g/s
50127.238 = WB in lambda
68.238 = EQ Ratio Commanded in lambda
50070.56 = engine RPM
11.92 = MAP in MPa
2313 = GMVE (mgK/kPa)
2126.240 = MAT in K
3 because it's a V6 (LFX)
Also recreated in Excel to see it in action and I'm getting the same numbers as in the Scanner. Replaced my numbers with Smokeshow's data (from the picture in his first post) and got a value of 33.904 (adjusted the formula slightly because he's using STFT and not a WB). The picture shows a "GMVE STFT%" of 0.3%, so by removing the *100 you'd get 0.33904 which would be like 0.33904% - is that correct? As if the *100 doesn't need to be there? Or did I just mess up the formula? Checked it like 27 times but you never know...
In any case I adjusted my VVE table in the idle zone by -5% to see how it would affect the math calculation, and the result of the equation went from ~-20% to around ~-22% at idle. I then increased this zone by 15% from here and the result was still around ~-20%, so it seems like adjusting the VVE table isn't affecting the formula much.
Am I missing something? Am I way off? Do we need to do something different on Gen V's? I also have "VE/MAP/MAT Cylinder Airmass" (VE Cylinder Airmass) and "Volumetric Efficiency Airflow" available (NA V6 so won't be hitting the max of 512 g/s or whatever it is). Should the VE Airflow and the MAF sensor read similarly at stoich?
And do the cells in the VVE table represent the same GMVE in the scanner (mgK/kPa)? By adjusting the VVE are you changing the GMVE? Should the two be roughly the same assuming your lambda/AFR are near commanded?
Any help would be much appreciated!
.33904 = 33.904/100 or 33.904%. So to get .33904 to read as percent, you multiply by 100. I'm not weighing in on what you do with those numbers, just confirming the math.
Indeed. The number I got with the *100 was 33.904 (%), however, the number I wanted/expected (with the *100) was 0.33904, or ~0.3% (what's in Smokeshow's first post/picture), and if you remove the *100 you'd get that. Not sure if I messed up my formula, or missed something, or just have no idea what I'm doing.
You'll have to compare the units of all different PIDs to see if one of those is reading in a different way (already changed to a percent),
The formula worked for me in Gen 4…
After playing around with the scanner and learning what it could do I was able to pretty easily tune the VVE. First I dialed in my MAF tune, then I applyed a comparison of MAF vs VE on the bottom graph as you can see. The percentage error between them is also there in yellow. I found this to be an easy way to tune the VVE, hope this helps someone. There really is no math here, just the PIDs for MAF and PIDs for VE in grams per second. Best of luck to all!
Last edited by Tunercharged; 03-29-2023 at 10:12 AM. Reason: Autocorrect issues
2017 Silverado 3500HD WT 6.0 flex fuel 6L90 6800lbs E78 T43
--- What am I doing??? Why did I do that???---
Okay so in comparing my numbers to Smokeshow's my dumbass forgot to change the formula from 3 to 4 for his numbers - after the change they add up correctly, so my formula is right.
But does that mean my VVE table is actually off by ~20%? Seems to run fine, although my transients are somewhat erratic - doesn't seem to affect drivability though.
Just looked at yesterday's log; after reducing the idle zone of the VVE table by 5% my VE Airflow and MAF sensor were pretty close, within 0.1 g/s at steady state; after the +15% change (today's log) the VE Airflow is off by almost 15%, but in both cases the formula shows ~-20%.
Is the VE Airflow equivalent to the "GMVE_af = (MAP*GMVE/IAT)*RPM/60*4" part of the formula? I see that "(MAP*GMVE/IAT)" is the same as VE Cylinder Airmass (VE/MAP/MAT Cylinder Airmass), and the "RPM/60*4" converts the airmass to an airflow. If this is the case then it makes sense that, as Tunercharged mentioned, you'd want the MAF and VE Airflow to be the same, and so perhaps I'll adjust my VVE table based on this difference and not worry about the formula.
Edit: Played around with my last two logs some more; if I use my "cylinder airmass" in the equation to get airflow ("GMVE_af") I get pretty much what my MAF says. If I do the same with "VE cylinder airmass", on my first log where I lowered the VVE zone by 5% there is a 25% difference between the formula and "VE Airflow"; on the second log where I then increased that zone by 15% there is a 10% difference (wasn't recording VE Airflow before so can't see if I was at 20% difference originally). Will try increasing the zone by another 10% and see if they match. meh.
Last edited by KillboyPowerhead; 03-29-2023 at 10:49 AM.
After I dialed in my timing and MAF fueling my VE airflow was lower than MAF airflow by around 30 percent from 600 to 3800 rpm and from 3800 rpm up the VE AF was lower than the MAF AF by about 15 percent. So now after modifying the VVE by first raising the whole table 15 percent and then another 12 percent for all under 4000 rpm, it is pretty good. Did a little smoothing on that rpm transition by eye and good enough. I then tuned the MAF a little bit again as there was compensation for the changes to be done there. I’m running MAF tune open loop only and very happy with this way to tune.
2017 Silverado 3500HD WT 6.0 flex fuel 6L90 6800lbs E78 T43
--- What am I doing??? Why did I do that???
Simple math I came up with for this exactly - 100 * ((([50040.71] * ([50114.156] + [50116.156])) - [2311.71]) / [50040.71]
You can use fuel trims or EQ Error - just swap the fuel correction out of the equation
This math also uses airmass instead of the MAF - (([50041.223]*(273.15+[50011.241]) * (1000/[50030.91]))
It'll get it within 10% typically first pass - I use this to get the general VE table and then the EQ error one to fine tune.
Both of these work with gen4's and gen5's...
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
So is the objective here to make the MAF sensor airflow and the "VE Airflow" match? Once they match you know your VVE table is good?
For the airflow formula "GMVE_af = (MAP*GMVE/IAT)*RPM/60*4", using my "cylinder airmass" (in place of "MAP*GMVE/IAT") gives a number near equal to the MAF sensor, but when using "VE Airmass" I get a number way off from "VE Airflow" (25% higher than VE Airflow when reducing idle zone by 5%, 10% higher when further increasing idle zone by 15%). Should the equation not equal VE Airflow if using VE Airmass? Looks like I'd need to increase the idle zone by a further 10% to make them match, but then the VE Airflow will be even further from the MAF sensor airflow (I think, based on the fact that the two were near equal when the zone was reduced by 5%, and off when the zone was increased by 15%). Hopefully this makes sense - starting to confuse myself...
Either way, going to try increasing the zone by 10% just to see what happens, then decrease back to where the two airflows were equal.
The airmass one depends solely on data acquisition and polling rate of the sensors involved. Plus if anything is off such as a VE multiplier or fuel correction somewhere it can make things "off" as well. Usually the airmass equation by itself with slow steady pedal inputs will get the VE table within 10% first pass and even closer the second pass. The VE correction formula does just as you said - makes maf, VE and dynamic all match one another which in a correctly tuned setup they nearly always do. I have my customers fail the MAF just to double check fueling on the VE table and it's almost always 1 to 7 percent out after using the equations with the 7 percent areas being some that aren't passed over a couple of times or with good data acquisition.
A LOT of the time O2 settings cause the most headaches with dialing in the MAF or VE tables. Large swings will cause fueling to require a 6% correction possibly one pass - then paste special multiply by half - and it's out 7 or more % the next pass. Then you think it's right or at least close and the next ignition cycle temp changes a little and things are back out 6 or 7 % again. O2 swings cause a lot of problems when not setup right
Last edited by GHuggins; 03-29-2023 at 04:23 PM.
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
Played around with the numbers some more. Using Smokeshow's formula and hjtrbo's on post 48 (GMVE = IFR * IPW * AFR * MAT / MAP) I can see that "VE Airflow" comes from the VVE table (guess the numbers in the cells mean mg of air?). So makes sense to me to adjust the VVE table based on VE Airflow vs MAF (assuming MAF is dialed in).
No idea where GMVE (mgK/kPa) comes from, however; seems bogus. Walking back the equation as I did for VE Airflow, the GMVE would imply an AFR of like 19.0 more or less (assuming all other variables are used in real time). Not sure if there's something else at play?
Anyway, I used this new calculated VE (based on VE Airflow, i.e. the VVE table) in Smokeshow's equation rather than the GMVE in the scanner and the result is much more as I'd expect; also tried the same thing using VE Airflow in place of the whole "GMVE_af" part and the two are fairly close, as expected.
Guess I'll adjust the VVE based on the VE Airflow vs MAF.
Thanks everyone!
GMVE is a lumped parameter. It is the volumetric efficiency, displacement, molar mass and gas constant all wrapped into one term. This cuts the arithmetic down from 5 steps to 2 steps...so it saves processor resources when it must be calculated in real time.
I have a question…one of the ways I was able to eliminate a lag during off idle and transients that was caused by my sheetmetal intake and intercooler design was by increasing my manifold volume setting by almost 30%. It worked great vs. screwing with the transient tables. Does that screw with the formula above? Does the GMVE lumped parameter use the new manifold volume setting for its calculation? I’ve attempted to filter out as much noise as I can in my log and steady state does not look bad, but there are some places in the VE table where I feel like I keep chasing my tail.
The formulas that HPT allows us to have are 'contextless'. What I mean by that, is they do not let us deal with (unless they've changed things and I missed them) data from any time other than right now. That's why we're limited to 'steady state'. In steady state, things don't change much, thus data from two samples ago is gonna be about the same as the data in the current calculation. This is why things like calibrating the MAT estimator's BIAS table is impossible inside of HPT. This has a further reaching consequences.
Here's a small snippet from what I wrote up back in 2008:
tuning the VE (or GMVE) consists of solving for GMVE:
GMVE= IFR*IPW*AFRwb*(IAT+(ECT-IAT)*BIAS)/MAP
This doesn't look too bad, right? Well, the kicker is that GMVE will be determined by BIAS, which by itself is determined by Airflow, which is determined by GMVE. You ever seen a dog chasing its tail?
You cant solve it separately, you MUST solve it simultaneously. But to do that, you must step away from HPT, it's just not doable.
No, manifold volume is not a component of speed density or the MAF. The manifold volume is used for MAP prediction...if you know the characteristics of the flow path (throttle body effective area, manifold volume) as well as your current mass flow rate, you can predict MAP in the future with some degree of accuracy. Like filling a glass of water, if you are pouring into it at a given rate and you know the volume of the glass, you can estimate when you will reach the top.
In your case, it may have helped the transient condition because that larger volume feeds back into the function that controls the throttle position...and tells it to open further initially to fill the extra volume, even if it isn't there. So the air inrush happens faster than the ECM is calculating. Lots of things can happen very differently on various applications and calibrations though, so I don't recommend changing that too liberally.
Thanks Smoke…knowledgable as always!
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