LGX VVE & MAF tuning questions

[Roland_Price]

Hi, everyone

I have a 2016 v6 Camaro with Edelbrock PD blower installed. I recently installed a FI Interchiller to cool that thing and I'm retuning the car. My last tuner didn't touch the VVE tuning so I have to do it myself and I have a couple of questions regarding it and MAF rescaling:

1) What will be the correct procedure of tuning VVE with DOHC on these engines? I know that it will take a significant amount of time, but since it's my car I'm willing to invest it. I read only the "Lock intake at zero" point, but haven't found the exact procedure how to log and adjust VE for different INT/EX cam angles. I did 20 graphs for all of the INT/EX pairs that are listed in my VT tables but not sure if it's the right way to log. If anyone here did this sort of tuning please weigh in on this process

2) Last time I did a MAF rescaling was when the car was still NA and I did 5-6 logs until the I had a sub 1% error along the line. Now I can't achieve a stable result until around 6000 Hz - every log I do has more or less random result of rich/lean 4-5% till I hit around 6000 Hz. Is this deviation normal for a MAF when using PD blower? Or maybe I have something that messes with the data? DFCO and cat overtemp is disabled, Dynamic threshold set to 100 and 90 RPM for disabling and enabling. I've attached the last iteration of a tune I run to log MAF and a couple of logs with it

Any info on these questions is highly appreciated

Thanks

[CYN_CRVR]

What filters are you applying to the log for assessing MAF errors? You're not logging Fuel Trim Cell, which I think is an important parameter. I used FTC < 7 as one of the filters for all my airflow tuning (MAF and VVE), and I didn't bother disabling DFCO.
https://forum.hptuners.com/showthrea...FTC-definition

Following is my complete filter for MAF tuning. The three lines are: FTC < 7, MAF steady state, and MAP steady state. You might have to adjust the "-40" number depending on your polling rate.
[6310] < 7 &
ABS([50040.71]-[50040.71.shift(-40)]) < ([50040.71]/[50040.71.shift(-40)])*0.1 &
ABS([2311.71]-[2311.71.shift(-40)]) < ([2311.71]/[2311.71.shift(-40)])*0.1

Speaking about polling rates, I think I counted 95 parameters in your log... are you really using all these? Reducing the number of parameters increases the polling rate of those that remain. You can prove this by exporting the log as a CSV without interpolation and opening it in Excel. I see MAP Hi-Res, Intake MAP (SAE), and Intake MAP A (SAE) (Hi Res) all in your log - but the first one alone should be sufficient, I think.

Regarding tuning VE on these LGX engines: my advice is don't bother zeroing your cams, and only make changes to the base VVE table. The HP Tuners VVE Editor doesn't do a good job of solving for the ICA and ECA coefficients. It's not that big of a deal, since you can still achieve good results just editing the base table.

[CYN_CRVR]

Oh, and also:

- Although the VVE Editor defaults to the "Manifold Switch Closed" table, it is the "Manifold Switch Open" table that the computer actually uses. This threw me for a loop at first, as I was making changes but not seeing any difference in results!

- Anytime you re-flash a tune or fill the fuel tank, be sure to wait long enough before logging, or your fueling will be off. To be really safe, I ended up just waiting until the 2nd or 3rd drive cycle after a flash before logging again.

[Roland_Price]

What filters are you applying to the log for assessing MAF errors? You're not logging Fuel Trim Cell, which I think is an important parameter. I used FTC < 7 as one of the filters for all my airflow tuning (MAF and VVE), and I didn't bother disabling DFCO.
https://forum.hptuners.com/showthrea...FTC-definition

Following is my complete filter for MAF tuning. The three lines are: FTC < 7, MAF steady state, and MAP steady state. You might have to adjust the "-40" number depending on your polling rate.
[6310] < 7 &
ABS([50040.71]-[50040.71.shift(-40)]) < ([50040.71]/[50040.71.shift(-40)])*0.1 &
ABS([2311.71]-[2311.71.shift(-40)]) < ([2311.71]/[2311.71.shift(-40)])*0.1

Speaking about polling rates, I think I counted 95 parameters in your log... are you really using all these? Reducing the number of parameters increases the polling rate of those that remain. You can prove this by exporting the log as a CSV without interpolation and opening it in Excel. I see MAP Hi-Res, Intake MAP (SAE), and Intake MAP A (SAE) (Hi Res) all in your log - but the first one alone should be sufficient, I think.

Regarding tuning VE on these LGX engines: my advice is don't bother zeroing your cams, and only make changes to the base VVE table. The HP Tuners VVE Editor doesn't do a good job of solving for the ICA and ECA coefficients. It's not that big of a deal, since you can still achieve good results just editing the base table.

Thanks a lot for these points.

1) I use this filter [2517.161.avg(1500)]=0 and [2517.161.avg(-200)]=0 and (abs([50090.156.slope(250)])+abs([50090.156.slope(-250)]))<2 and [6310.avg(250)]=9 it's not mine, I got it from the GoogleDrive of the guy who made the MAF & VVE Assistants. I will try yours and see how it goes

UPDATE: I had to change [6310] < 7 to 9 since it was always on 8 while accelerating, not sure if it's right though. As for the polling rate - can you please specify how can I tweak the interval in filter to my needs? 40 clears all the data for me

2) Yeah, I was using 4 different sets of channels for different purposes for the reason of polling rate and at one point I merged them for I don't remember what purpose and totally forgot about this issue. Thanks for pointing it out, I'll clean it up

3) Can you please specify what do you mean by the base table? Is it the one with the cams set to 0/0 degrees? AFAIK this table will be used only for this set of degrees and it's basically idle only

[Roland_Price]

Oh, and also:

- Although the VVE Editor defaults to the "Manifold Switch Closed" table, it is the "Manifold Switch Open" table that the computer actually uses. This threw me for a loop at first, as I was making changes but not seeing any difference in results!

- Anytime you re-flash a tune or fill the fuel tank, be sure to wait long enough before logging, or your fueling will be off. To be really safe, I ended up just waiting until the 2nd or 3rd drive cycle after a flash before logging again.

1) yeah, I had this one catch me off guard as well, I now change both tables simultaneously

2) Good point, I totally forgot about the heatsoak and such stuff. I will try giving the engine more time before starting logging stuff

[CYN_CRVR]

Thanks a lot for these points.

1) I use this filter [2517.161.avg(1500)]=0 and [2517.161.avg(-200)]=0 and (abs([50090.156.slope(250)])+abs([50090.156.slope(-250)]))<2 and [6310.avg(250)]=9 it's not mine, I got it from the GoogleDrive of the guy who made the MAF & VVE Assistants. I will try yours and see how it goes

UPDATE: I had to change [6310] < 7 to 9 since it was always on 8 while accelerating, not sure if it's right though. As for the polling rate - can you please specify how can I tweak the interval in filter to my needs? 40 clears all the data for me

2) Yeah, I was using 4 different sets of channels for different purposes for the reason of polling rate and at one point I merged them for I don't remember what purpose and totally forgot about this issue. Thanks for pointing it out, I'll clean it up

3) Can you please specify what do you mean by the base table? Is it the one with the cams set to 0/0 degrees? AFAIK this table will be used only for this set of degrees and it's basically idle only

1) Oh, right - I remember trying those too, but I didn't feel like they worked particularly well for me. The ones I ended up using were originally posted by another experienced tuner, and they make more sense to me. If -40 clears all your data, try -20 or -80. If still no data, try -10 or -200.

3) Correct - by base table I mean 0/0. However, this table does affect the VVE value for all cam values. The VE calculation at all times is a simple linear combination of all the coefficients and variables:
VE = c1 + c2*MAP + c3*MAP^2 + c4*MAP*RPM + c5*RPM + c6*RPM^2 + c7*MAP*ICA + c8*MAP*ECA + c9*RPM*ICA + c10*RPM*ECA + c11*ICA + c12*ICA^2 + c13*ICA*ECA + c14*ECA + c15*ECA^2

When you edit the base 0/0 table for a given zone, it adjusts the first 6 coefficients in the above equation, and that's all you really need to reduce your VVE errors since these 6 terms are being used at all times. The terms involving ICA and ECA can be left stock. I have gotten strange results when editing the VVE tables that have nonzero values for ICA and ECA, probably because the solver engine struggles to solve for that many additional terms. The only downside of tuning this way is if you later change your cam angle tables, you might need to do another tuning iteration to dial-in the VVE in the zones where you changed the cam angles.

[Roland_Price]

1) Oh, right - I remember trying those too, but I didn't feel like they worked particularly well for me. The ones I ended up using were originally posted by another experienced tuner, and they make more sense to me. If -40 clears all your data, try -20 or -80. If still no data, try -10 or -200.

3) Correct - by base table I mean 0/0. However, this table does affect the VVE value for all cam values. The VE calculation at all times is a simple linear combination of all the coefficients and variables:
VE = c1 + c2*MAP + c3*MAP^2 + c4*MAP*RPM + c5*RPM + c6*RPM^2 + c7*MAP*ICA + c8*MAP*ECA + c9*RPM*ICA + c10*RPM*ECA + c11*ICA + c12*ICA^2 + c13*ICA*ECA + c14*ECA + c15*ECA^2

When you edit the base 0/0 table for a given zone, it adjusts the first 6 coefficients in the above equation, and that's all you really need to reduce your VVE errors since these 6 terms are being used at all times. The terms involving ICA and ECA can be left stock. I have gotten strange results when editing the VVE tables that have nonzero values for ICA and ECA, probably because the solver engine struggles to solve for that many additional terms. The only downside of tuning this way is if you later change your cam angle tables, you might need to do another tuning iteration to dial-in the VVE in the zones where you changed the cam angles.

Thanks! I will try adjusting first step of VVE tomorrow and see how it goes. Is there a way to not get garbage data on EQ err and still have the safety of the CL regulation with O2 sensors? My VVE is way off since it's still NA - it won't even start normally, it's super lean

[CYN_CRVR]

Thanks! I will try adjusting first step of VVE tomorrow and see how it goes. Is there a way to not get garbage data on EQ err and still have the safety of the CL regulation with O2 sensors? My VVE is way off since it's still NA - it won't even start normally, it's super lean

Unfortunately, I don't have any tuning experience with blowers or wideband sensors. I know wideband is essential for WOT tuning, and I've read that it is otherwise best to use the OEM narrowband sensors for partial throttle tuning because that's what the ECM relies on.

[Roland_Price]

Unfortunately, I don't have any tuning experience with blowers or wideband sensors. I know wideband is essential for WOT tuning, and I've read that it is otherwise best to use the OEM narrowband sensors for partial throttle tuning because that's what the ECM relies on.

Yeah, I have AEM wideband in my setup. I'll try adjusting the VE and see how it goes from there

[KillboyPowerhead]

What does the "shift" function/filter do? Been Googling HP Tuners for an hour now, and unless Google sucks, the Shift filter hasn't been explained one single time ever by anyone (lol). Does it take the value of a parameter at the requested time? So...

[50040.71]-[50040.71.shift(-40)]

...means current/instantaneous MAF (g/s) minus MAF (g/s) from 40 ms ago?

Edit: Ha! Found an explanation, from HP Tuners of all places (minor sarcasm... took a dozen different searches to pop up): https://www.hptuners.com/help/vcm-sc..._variables.htm

[Roland_Price]

What does the "shift" function/filter do? Been Googling HP Tuners for an hour now, and unless Google sucks, the Shift filter hasn't been explained one single time ever by anyone (lol). Does it take the value of a parameter at the requested time? So...

[50040.71]-[50040.71.shift(-40)]

...means current/instantaneous MAF (g/s) minus MAF (g/s) from 40 ms ago?

Edit: Ha! Found an explanation, from HP Tuners of all places (minor sarcasm... took a dozen different searches to pop up): https://www.hptuners.com/help/vcm-sc..._variables.htm

Thanks for bringing it here, I was gonna ask this one too