E38 VVE tuning question? Lower load cells don't seem to be responding...

[JLawson240]

I spent a few hours doing some VVE tuning on a friend's truck today (2012 Silverado BTR Truck Norris cam only) and made some solid headway, but noticed that the lower load cells and the idle area didn't seem to change much at all after 4 rounds of logging/tuning. I used STFT to tune today and obviously made sure to stay away from PE and tuned drivability areas only. The following steps were taken:

-Disabled MAF by lowering frequency to 2hz and set P0103 to MIL on 1st error
-Disabled LTFT and closed loop enable by maxing out temps
-Disable COT and DFCO

Trims started off super fat in the 16-26% rich range across the board. Again, after 4 rounds of tuning I could see noticeable improvement in all areas of the histogram I created except for the very low load areas and idle range some. They came down a hair at best but essentially remain 15-20% rich in all areas I've described. When I copied and pasted the histogram each time I pasted Multiply by % half to make incremental adjustments.

My question is am I missing something. Is the ECU controlling fuel in another manner in these areas not allowing the changes I'm making to take hold? Any help would be greatly appreciated. Novice at this.

PS- After today's VVE tuning and last week's MAF tuning the truck runs 10x better. All idle surging issues, RPM dropping too quickly after a rev, etc. have been completely resolved.

[Alvin]

There is a PID MAF state or MAF failed state or something like that.. I like to make sure its showing the MAF failed by that pid before starting VVE tuning.

[[email protected]]

I am having a similar issue on the same platform. I have a 2013 GMC Sierra 5.3 with a Scroggin Dickey's hot truck stage 1 cam. I am actually using an AEM wideband as the WB EQ Ratio on my histogram. I started out adding about 12% to the VVE to make sure I started out rich and try to tune toward stoichiometric. After a few rounds of adjustments everything seemed to just get richer even when I was tuning toward stoichiometric. I checked before I started and the MAF was definitely failed. I think I'm going to scrap those and start over.

There are 4 VVE tables on mine based on the manifold switch and DOD. I have DOD disabled obviously so I ignored those. I started adjustments in the manifold closed table and just copied to the manifold open VVE table. I've heard people starting with either and copying to the other as long as your manifold doesn't have a switch for the intake runner length. I'm very unsure on this.

Which VVE table did you use?

[JLawson240]

I copied my manifold open table to the manifold closed. So now they are exactly the same. I know that my MAF was failed as well, I'm still hoping somebody pops on and sheds some light.

[GHuggins]

Manifold Open = Open runner controllers for variable intake manifold runners - never seen one of these on a GM truck or performance car, so the one that is labeled OPEN is the one for them missing. Either way - just copy and paste like y'all are doing will work just fine.

Fuel correction editing - might want to read up on or look into rich after flash. It takes a minimum of 20 minutes with the engine running for injector tip temp to come back down around 60 or so degrees Celsius. This is the "normal" operating area of the engine - however it is a really good idea to tune in the upper temp zones - this assures you don't have overly rich hot starts after filling up at the pump or running in and back out of the store real quick. You're most likely fighting this. I know I did really bad before I knew about it...

Hope this helps get you sorted.

[JLawson240]

Thank you! That makes a ton of sense. I've stumbled across the concept in my self teaching but obviously haven't wrapped my head around it yet. I'll keep doing my homework

[[email protected]]

I don't know any of this to be fact, but it seems like the lower load cells of the VVE table (rows near the top) get skewed by low throttle cell hits. What I mean by that is if you have DFCO disabled it will keep fueling when you get out of the throttle instead of going lean, but it seems like it defaults to a kind of rich value. Every time you log you would be averaging in those rich data hits with all the rest.

I bought the Gen 4 training videos from Evan's Performance Academy this evening. I was watching the Speed Density tuning videos. I learned two new things that is very helpful.

1.) On some of the E38 operating systems you can apply an HPT OS 2 Bar patch to the operating system that does away with the VVE and gives you a traditional style VE table. It is not available for the E67. Per Evan's even with this " OS 2 Bar patch " you can still set it up for 1 Bar and run an NA setup. This is available on mine and I think I'll give it a try.

2.) In the VCM scanner, if you go into the graph layout for your histogram, under filtering you can out data hits by a parameter. This could be relevant to this thread because you can filter out data hits by throttle position. So if low throttle data hits were causing your low load areas to go rich, you could maybe filter out hits that are at less than say 10% throttle.

[ttz06vette]

The min airflow tables under idle also seem to effect these areas as well.

[Tunercharged]

I don't know any of this to be fact, but it seems like the lower load cells of the VVE table (rows near the top) get skewed by low throttle cell hits. What I mean by that is if you have DFCO disabled it will keep fueling when you get out of the throttle instead of going lean, but it seems like it defaults to a kind of rich value. Every time you log you would be averaging in those rich data hits with all the rest.

I agree with the DFCO being off causing the rich observations you are seeing, I?ve noticed it too. So what I?ve also found is that if I disable Closed Throttle downshift torque management on my 6L90 with the DFCO disabled it will cause it to not be as rich as if it is enabled. Also I noticed that fueling during idling will be more consistent with the CT downshift torque management disabled.

[JLawson240]

I've heard alot about those patches that go back to a traditional VE table. If someone could elaborate on how that is beneficial I'm all ears to learn.

[GHuggins]

Use this while you're setup to run on 100% MAF and whilst tuning in your MAF as a math formula to back calculate the VE table -
(([50041.223]*(273.15+[50011.241]) * (1000/[50030.91]))
This uses airmass and temperature readings to back calculate the VE table. The slower the pedal movements the better your data will be. Usually 2 passes like that will have it almost spot on.

Benefits of a 2bar primarily are the baro update - will no longer take place with wot throttle keeping boost from throwing it off and it gives you boost enrichment settings to change - mainly just good for turbo builds on the boost enrichment part and all boost builds where available for the baro update part. The other part is it doesn't use coefficients, so a change you make stays...

E67 does indeed support 2 or 3 bar OS patches - like all of the ECM's though - may or may not be available - just depends on whether or not hpt put it in...

If you're going to get tuning materials - get Greg Banish's stuff - more worth it... Never hurts to study multiples, but Greg's an actual engineer...

[JLawson240]

Use this while you're setup to run on 100% MAF and whilst tuning in your MAF as a math formula to back calculate the VE table -
(([50041.223]*(273.15+[50011.241]) * (1000/[50030.91]))
This uses airmass and temperature readings to back calculate the VE table. The slower the pedal movements the better your data will be. Usually 2 passes like that will have it almost spot on.

Benefits of a 2bar primarily are the baro update - will no longer take place with wot throttle keeping boost from throwing it off and it gives you boost enrichment settings to change - mainly just good for turbo builds on the boost enrichment part and all boost builds where available for the baro update part. The other part is it doesn't use coefficients, so a change you make stays...

E67 does indeed support 2 or 3 bar OS patches - like all of the ECM's though - may or may not be available - just depends on whether or not hpt put it in...

If you're going to get tuning materials - get Greg Banish's stuff - more worth it... Never hurts to study multiples, but Greg's an actual engineer...

Thank you!! I?ve got both of his books and read them cover to cover twice recently to really refresh myself before I go full throttle into this.

[Alvin]

There are 4 VVE tables on mine based on the manifold switch and DOD. I have DOD disabled obviously so I ignored those. I started adjustments in the manifold closed table and just copied to the manifold open VVE table. I've heard people starting with either and copying to the other as long as your manifold doesn't have a switch for the intake runner length. I'm very unsure on this.

Which VVE table did you use?

VE Normal IMRC Open is the only table it uses. You can leave the rest 0's. I do just to avoid confusion.

[[email protected]]

Use this while you're setup to run on 100% MAF and whilst tuning in your MAF as a math formula to back calculate the VE table -
(([50041.223]*(273.15+[50011.241]) * (1000/[50030.91]))
This uses airmass and temperature readings to back calculate the VE table. The slower the pedal movements the better your data will be. Usually 2 passes like that will have it almost spot on.

Benefits of a 2bar primarily are the baro update - will no longer take place with wot throttle keeping boost from throwing it off and it gives you boost enrichment settings to change - mainly just good for turbo builds on the boost enrichment part and all boost builds where available for the baro update part. The other part is it doesn't use coefficients, so a change you make stays...

E67 does indeed support 2 or 3 bar OS patches - like all of the ECM's though - may or may not be available - just depends on whether or not hpt put it in...

If you're going to get tuning materials - get Greg Banish's stuff - more worth it... Never hurts to study multiples, but Greg's an actual engineer...

Do you setup this equation as a custom math parameter, then create a separate table/graph and set that math as the parameter? Then just let that fill in the VE in the background?

[GHuggins]

If I understand your question correctly - yes, then just copy and paste into the VVE table in the editor and blend the areas that need blending in where the outliars might throw things off a little - such as the decel zones - usually skews it a touch, but if you can free rev it up through the rpms easy then you can usually use that for good actual data in those decel zones...