Nicolas L

So the way I understand it, a real VE table, by definition should match the volumetric efficiency of the engine at on a MAPxRPM (in our case) table.
Maybe most of you do it this way already, but my VE table is not that, it puts the VE value so my ECU gets me the AFR I want, which is great, car drives fine, no issues.

However, this makes the AFR table kind of a moot point once everything is set. I could enable incorporateAFR and change the AFR table if I ever want to modify my tuned VE table, but I honestly see no difference from just changing the VE values.
Another issue is that when I'm tuning my timing table, I don't really know which parts of the RPM range are more efficient to avoid having too high of timing there, it's not 100% clear because I don't necesarily get higher VE numbers in the peak torque area if there was inconsistent AFR in that area during VEAL.

So I've been thinking of going out there and set my VEAL target to a fixed number, say 14, driving around, let it find the VE, and then building the AFR table to set the cruise, idle, and WOT areas accordingly and never touch my VE table again.
This way I can tune spark while looking at a real VE table and not cranking up the timing in areas that are already very efficient.
What are your thoughts on this? I could always restore my old tune if this is a **** idea, but I didn't pay anyone to build my tables so I'm not concerned about spending some more time on this.

shuiend

iTrader: (24)

Are you on a load bearing dyno? You have a good idea, but without a load bearing dyno it is extremely hard to accomplish on the street,

Nicolas L

Unfortunately no, I'm on the street, I see your point. But the "fake" VE table is built just as shitty, maybe I'd be able to see some kind of trend in values and interpolate per RPM column.

x_25

I mean, this is sort of what I did. I set my target AFR table to 14.7 for most of it (excluding idle and anything above 70kpa or so) and tuned with incorperate afr on.

Issue ended up being, since I have a 1.6 and fairly large injectors, the pulse widths are very small in the cruise range and I am into the non linear part of the curve, so I still had to retune the VE table a bit after changing the target AFR table to where I wanted it.

18psi

iTrader: (76)

This will not work consistently

DNMakinson

iTrader: (3)

It sounds like you are envisioning “incorporate AFR” exactly opposite of what it is. Look in the manual at the fueling equation.

Incorporate pulls the AFR out of the VE table, making it a real VE table. As best as it can.

I would not recommend running 14.7 AFR in boost.

Possibly I misunderstood your post.

DNM

Nicolas L

Below is the way I understand it.

The formula with incorporate AFR is:
PW = ReqFuel * VE(rpm,map) * MAP * stoich / targetAFR(rpm,map) * GammaE

Having that option off removes what's bold, or makes it =1 rather, which is the same as writing 14.7 all over the AFR table if your stoich settings are set to 14.7.

So for example, if you were to set a VE cell to 100, incorporateAFR will multiply that up or down based on the relationship of the corresponding AFR cell number and your stoich value, completely unrelated to the real number the gauge shows. Which is stupid and confusing for beginners IMO.

So imagine now that those 100 in that cell makes your wideband show you 12.5AFR. and that in the corresponding AFR table cell you also have 12.5:
You'd think that since you already had 12.5 nothing would happen right? Well, according to the formula above, if you turn incorporateAFR on, the value you're adding is 14.7/12.5, so now the 100 VE will be multiplied by 1.176, so it will be even richer, even though your AFR table matches your original VE-only AFR.

If you had a real VE table and those 100 in the VE cell gave you 14.7, you could set your AFR to 12.5, and I don't know if it will give you exactly 12.5, but you know that if you write 12.5, it will be richer than stoich, and not ???. I think they should just name that table VE multiplier, because that's all it does.

My point was that i'd like to see REAL VE for things other than fuel, I find it useful when tuning spark because I know where the engine is more efficient and will want more or less timing. I tried today with everything set to 14.7 and I can already see the gradient that corresponds with the peak of torque. Once I smooth this out I can play with the AFR table to make the WOT richer. The benefits of this should be that I don't have to fiddle with each row, but I can just group a bunch of cells I want at say 12.5 and another group I want lean in cruise and let it do the math (hopefully)

DNMakinson

iTrader: (3)

You either turn on INC AFR, or not. You do not switch back and forth. EGO, or your manual tuning will push the VE table to give you the AFR in you AFR table.

If you wish, on a given occasion, to run a full stoichiometric VE, then you should normally tune to your normally desired AFR targets with Incorp AFR turned on. Then EGO and Auto Tune will create a true VE table.

Next, on that said occasion, simply change your entire AFR table to 14.7 and that is close to where you will now be driving.

That is why the FW guys began using INC AFR, to build a true VE table.

If if you want the amount of fuel injected to follow you changes you make to your AFR table with nearly 100% EGO, then you have to tune with INC AFR turned on.

At at that same 100 VE you quoted, if INC AFR is off, changing your AFR target table will not affect your fueling except by EGO forcing it.

That’s all I have.

Nicolas L

Oh I see what you mean.
If I tune the VE with incorp on to match the AFR table, I should still get a real VE table, because what makes that value match the AFR table is the multiplier. In other words, turning off incorpAFR in a cell that results in a 12.5 measured AFR and also matches the AFR table, should result in a measured 14.7 or close. (This probably sounds confusing but I'm agreeing with you)

So basically turning on include AFR and tuning the VE to match it should result in a real VE.
I'm slow I guess.

Thanks! Talking it out helped lol.

DNMakinson

iTrader: (3)

Exactly. For the same final pulse width, the AFR is either accounted for in the VE table itself (Incorp Off) or in the fueling equation directly (Incorp On).

I work for Pos Cats .
DNM

intenseapple

I'm going to do a little thread necromancy here because I feel that this question was only halfway answered. In my case, I have a nearly fully tuned VE table WITHOUT Incorporate AFR Target ever being turned on. The car runs well and AFRs are fairly solid, only needs a few tweaks here and there. However, I plan on potentially running more boost and ethanol in the future and think it would be nice to simply resize my VE, spark, and AFR tables to allow for more KPAs and then rescale my AFR table for different AFRs. In a case like this, is it worthwhile to go through the process of retuning my VE table with Incorporate AFR enabled? Are there any other benefits to having a "true" VE table?

DNMakinson

iTrader: (3)

I did it by using the fueling equation and Excel to back calculate the removal of AFR from the VE table. Then turned on IncorporateAFR.

It was fairly painless.

That is the how, I’ll leave it to you to justify the why. It just makes sense to me to Incorporate.

DNM

intenseapple

gotcha, I figured something like that wouldn’t be too painless. I’ll go ahead and try it, thanks!

Panici

I tune with Incorporate AFR on.
As said gives you something closer to a real volumetric efficiency table.

Having a real VE table is nice as when you make airflow changes (intake/exhaust/cam/turbo), you can directly see how this affects the engine's VE.

I also find it nice to tweak the AFR table as needed and have it actually chance the AFR to what I want.
Usually I fatten up the AFRs at trackdays for extra protection.

I have found Incorporate AFR to work very well for both a Speeduino and MS3X (on a different platform/engine) once the maps are dialed in.