Silly Question about Incorporate AFR Table and the VE table

[LiquidCMR]

Please don't beat me on this one, I have searched all over and have not found an adequate answer.   

 

I have my General Settings set to Incorporate AFR table (enabled).  I have used VEAL and have a good VE table.    Lately, I've been messing with idle and I wanted to lean it out.  I have keep reducing VE values in my idle range and it seems like my AFR never really changes...it may lean a little but then goes back into the high 12's or low 13's.    My stupid question is, since I have Incorporate AFR Table enabled (which happens to be set to 13.0 for idle), what if any effect will VE table changes have on my actual AFR?   I'm starting to think that I could change the VE's all I want, but AFR will just auto-correct to what I have in my AFR table....is that correct?      If that is correct, why would anyone ever change their VE table if the have Incorporate AFR table (enabled)?

 

Tonight I will go and change my AFR table to 14.5 for the area where my idle lives, but I still have the questions above.   I would appreciate your collective insights.

 

Thank you,

 

- Liquid

[winstonusmc]

Do you have the ego correction enabled? Once you have the VE table spot on, you can adjust you desired AFR in your AFR table. The AFR table will be important using EGO correction and during VEAL. Also, so you have any type of idle VE enabled? That will also affect the AFR at idle.

[LiquidCMR]

I have EGO enabled but I don't think my settings would effect the car at idle (see attached image).   Not sure what you mean by idle VE enabled.  I have WUE enabled.         I have also attached my current tune for anyone who like to take a look.   

 

Note:  I did not change my settings last night but noticed the car was much leaner at idle compared to the other night when I was making the changes and burning them.    How can that be?  It's almost like as I burned them interactively with the car running  they weren't doing anything....but when I restarted the car the next day they did take effect.  Does that make sense?

 

Thanks again.

Original_2017-12-05_10.36.02.msq

[winstonusmc]

I have an MS3, it has idle VE. I wasnt sure what MS2 didnt have compared to MS3. I am not too familiar with the batch firing. I know it can get kinda funny at lower RPMs with batch fire. I skipped these problems and went straight to sequential on an MS3. I also ran a MAF on my L28ET, very easy to tune the fuel. I use VE on my RB25 though. 

[Chickenman]

 

 

Auto Tune does not always work particularly well at idle. Especially with larger camshafts. Same with EGO control.

 

You want to Manually control your Idle settings in most cases. So you want to run idle in Open Loop.

 

Set your EGO control to minimum RPM of about 1300. Set your Auto Tune to a minimum RPM  of 1300. Now O2 control and Auto Tune will leave your idle cells alone.

 

You can also " Lock Out " Auto Tune at idle ( and any other area ) by opening Auto Tune section and right clicking the VE Cells in a particular area. I usually lock out Auto Tune at Idle . There is a selection to lock the Cells. You have to select a " Block " of cells about 3 x3 all around your idle RPM. Richr Click. Lock the Cells. They should change to Gray in color when you save the changes. Now Auto Tune will leave those Cell areas alone, but you can still change them manually in the Main VE table. 

 

BTW, if you are running Batch fire 14.5 is too lean at idle. Aim for around 13.8. . Keep your AFR's at 13.8 just off idle to about 2,500. That will aid in light throttle transition. 

Edited December 7, 2017 by Chickenman

[Chickenman]

Here is a screen shot of the settings in the Auto Tune VE Table. Take note of the Gray " "Locked out " idle settings and the minimum RPM settings. Effectively this set-up is redundant. Either using Minimum RPM of 1,300 or Cell Lock out would work. 

 

I tune idle by the old school, highest RPM and Vacuum reading at idle method. That will always give you the most stable idle on any engine.

Edited December 7, 2017 by Chickenman

[Chickenman]

BTW, the reason why you select a " Block " of cells around your idle RPM, is that Tuner Studio ( regardless of weather Auto Tune or O2 correction is enabled ) is always weighing the Cell values AROUND the selected cell to calculate the current injector PW timing. This is called weighting and must be taken into consideration. 

[LiquidCMR]

Great info guys, thanks!     Chicken, may I see your AFR table, or perhaps you can comment on mine (image attached).    I'm in Buffalo , NY where the weather had officially turned to crap, so I'll be focusing on just idle tuning in the garage for a while.       

 

General tuning question:   If I have Incorporate AFR table (enabled), does making VE table changes work, or does the AFR table take over and basically negate the VE changes?

 

Thanks again,

 

- Liquid

[Chickenman]

The Requested ( Target ) AFR Table VE table and Auto-Tune all work together to generate the Injector Pulse width required. 

 

You should always have the Incorporate AFR  Table enabled. Disabling it will require a whole new Tune as Tuner Studio uses a completely different algorithm to calculate the Fuel curve. You can not switch back and forth between the two. 

 

The AFR table is a Target AFR . Think of it as " Requested AFR " . The figures are entered by the person Tuning the engine and some knowledge of ICE fuel requirements is needed. The VE  Table calculates how much air volume the engine should be requiring. The Tuning program then  uses various algorithms that combine the VE Table and the Requested  AFR ( and other parameters )  to generate an injector Pulse Width  appropriate for the exact conditions at a particular Load and RPM.  

 

Definitely making  manual or Automatic changes to the VE Table will work with Incorporate AFR enabled. It is the basis for all of the Tuning steps. The VE table is a ROUGH calculation of how much air the engine consumes. It can be quite accurate... or out miles. Depends on Data entered.  But the Target AFR table is the main controller. Even if the VE Table is totally out to lunch, using Auto Tune will eventually correct the injector PW to try and match the Requested AFR at a particular RPM and Load. The more accurate the original VE Table that is generated, the less work Auto -Tune has to do. 

 

Manual tuning comes into play to " Help " Auto-Tune speed up the process. Or when an experienced Tuner uses a Load Cell dyno to Tune the car.  The more you use Auto-Tune, the better it will get things adjusted. But initially your fuel curves may be pretty far out of whack. You can see this in the 3D view of the VE table after running Auto-Tune. You will start to see sharp Peaks and Valleys in the 3D Table. This is due to Auto-Tune correcting some values, but missing others ( for numerous reasons ). That is where manual " smoothing " or " Interpolation " is used. 

 

 

 

[Chickenman]

You have to be careful comparing AFR Tables ( and Spark Timing Tables ) between two engines. Unless they are identical. You need more info on the engine. Things like Cam duration, CR , is an Intercooler used, Fuel Octane, Meth Injection etc. Then you can make an educated estimate . 

 

In general, your table looks OK. I would be be a bit concerned about your AFR above 160 KPA. For a baseline Tune I like to see them a bit richer.  IE in the 11.5 to 11.0 range as boost climbs. Being too rich won't burn holes in pistons. Being too lean will. Auto-Tune is quite slow. It cannot correct a Lean condition under Full Boost fast enough to prevent detonation from happening. So you always want to set your baseline Tune a bit Rich under high Loads. Then let Auto-Tune lean it down slowly. This is how you Tune on a Dyno. Start off with conservative Fuel and Timing curves. Them ramp them up as you get the Tune dialed in to build HP. But always start off a bit rich under High Loads and RPM's and always keep the Spark Timing conservative. 

 

I really don't like to post up pictures of AFR and Spark Tables, because one size does NOT fit all. But if you PM me and give me all your engine details I'm sure I have something that will gain you a bit of fuel economy and be  a bit safer at higher boost. 

 

 

 

 

 

Edited December 7, 2017 by Chickenman

[LiquidCMR]

Chicken,

 

I PM-ed you with more details about my engine/setup.    I thought I could attached screens and my tune to the PM, but I couldn't....so I put them here in the post.

 

Thanks again!

 

- Liquid

 

Original_2017-12-05_10.36.02.msq

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