VemsTune and 1.1.6x release

[mattias]

Sprocket:  With the old system using only a cold/hot pulsewidth - changing from alternating to all banks would result in as much more fuel as the number of cylinders you had. So if you had 4 injectors and 4 ms warm start pw, you would get 4 ms x 4 cyl = 16 ms on each 4-stroke cycle. All injectors went from firing once each cycle to firing at every ignition/injection event, the pulsewidth stayed the same.

With the new "enrichment" strategy the pulsewidth is calculated and you're given the option of dividing it over the 4-stroke cycle, so you only get the fuel more often but the total amount is always the same. That makes it possible to use the same cranking tables regardless of your injector strategy for cranking.

My engine starts just barely better when I don't use alternating, simply because fuel is injected more often so the chance is higher that the engine gets some on each intake stroke.   Yes, I would've liked to see true sequential fuel injection implemented soon as well to see what difference that can make for both cranking, idle and low load quality and power.

[Sprocket]

Well there you go

These things need to be explained better as those upgrading from earlier firmwares could well become unstuck, when no one describes what has changed.

I wont butt in now as its clear the differencies in firmwares are huge, and what has gone before relates little to what is availble now, still without real explanations of differencies.

The post above is a real explanation, and made it 100% clear. Thanks

[GintsK]

Today I wonders how easy startups new engine with 1.1.54 strategy from Andrey.
1.1.64 have good thing: afterstart enrichment is in separate table. I think it is necessary.
I hope lost additional cranking fuel is just bug. And not dropped on purpose.

[lugnuts]

Why did they reduce the cranking fuel table from 8x8 to 4x4???
Is it going to remain that way?

Does 1.1.6x have the same Boost DC per Gear as the 1.1.47??

[GintsK]

main reason was e85 at low temperatures where cranking enrichment requirements are way different than aftersart enrichment.
Are you expect some difficulties with 4 point graph?

[MWfire]

Why did they reduce the cranking fuel table from 8x8 to 4x4???
Is it going to remain that way?

Does 1.1.6x have the same Boost DC per Gear as the 1.1.47??

becouse now there is crank curve and afterstart cure
1.1.6x doesn't have Boost DC per Gear as the 1.1.47, but i'm working on that.
BTW 1.1.65 has fix for afterstart enrichment

[mattias]

These things need to be explained better as those upgrading from earlier firmwares could well become unstuck, when no one describes what has changed.

I wont butt in now as its clear the differencies in firmwares are huge, and what has gone before relates little to what is availble now, still without real explanations of differencies.

Until now there has been no good documentation built-in to the system, and none of the firmwares we are talking about have ever been "official" although advanced users are using them.. or rather "testing" them on their own risk.

To make the upgrades easier we will add "configlets", or sub-pieces of config that will apply sane settings and tables for a sub-set of the config. So if you want to convert you can simply apply cranking and afterstart enrichment that will automagically work if you set the req fuel value using the standard equation. 

Even now VemsTune applies sane defaults when you upgrade, so it's not as bad as you may think to upgrade.

The post above is a real explanation, and made it 100% clear. Thanks

Thanks, I will add my explanation to the built-in "Press F1 for help" dialgos.

main reason was e85 at low temperatures where cranking enrichment requirements are way different than aftersart enrichment.
Are you expect some difficulties with 4 point graph?

When myself and Emil were in Hungary we enforced the split of the 1x8 cranking table into two tables for both cranking and afterstart (as of 1.1.63).

While E85 is a good reason even regular gasoline also has a "knee" in the graph where demand raises pretty dramatically, it's just shifted down in temperature. With only four cells you can focus enrichment on the most important temperatures, more points would be nice but it really doesn't need much more than this. It's radically better than the two pulsewidths we had before.

Tuning the cranking enrichment is a really hard job for anybody! I can only imagine how much effort has gone into that kind of research at Bosch and others who make industry systems. I like the graph you presented above : http://www.vems.co.uk/VEMSUserManual/CrankFuelling.png

You can imagine that with gasoline you can get a pretty small error with only four cells in the cranking table, example temperatures : -30, -10, 20, 70
I will make a good default table for my car and test on a few others, it will make it into the default configurations and configlets.

BTW 1.1.65 has fix for afterstart enrichment

I'm pretty sure you mean cranking enrichment? We both, you and me, have noticed how we bottomed out the values in the table so we need to scale things up. It might make it into 1.1.66 real soon.

[lugnuts]

I agree, 4 point cranking enrichment is a big step forward, I was just worried because we had 8 points before.

What about using 4 points for the Warm-up Enrichment? To allow 8 points for cranking?


Can you guys make my simple "Boost DC Per Wheel Speed" in the next revision? It's very good for drag racing FWD cars, and very easy to set-up.

VEMSTune Questions:
1) What do you do for datalogging? What exact method is being used now on what version?
2) Is there any way to hack the logs to work with MegaLogViewer?

[GintsK]

I think 4 points for WUE is too less. Currently I use WUE table for some protection purposes when engine comes overheeted.

[lugnuts]

That's a good point, I do that as well. I was just trying to think of a way to get the 8 cranking points back.

Overhead could be added to the "Safety" section as well.


What do you use for datalogging?

[AVP]

how will the engine benefit from more fuel during idle or normal cruising once overheated? For example if you go at 100C CLT and at that point you go to 105% of VE, how much reduction do you get on the CLT? On the other hand, isnt your lamda recalculating the fueling back to 1.00 on idle and cruising anyway? Unless you are doing this for drag and track purposes,in which case i can understand it. But for normal everyday use, i think it makes things more complicated.

I think the best way to avoid overheating is a large radiator and a lower degree thermostat.

On version 1.1.27 which i still use and works fine, you only have 2 cranking temps.So far,for the 440cc @3bar injectors i use, as well as 630cc which other have used on the audis, they had no problems with the cranking. So to go to 4 bin table is a good improvement i guess, but i wouldnt think anything more is needed.

Warmup enrichments do need to stay as they are, as well as the ability to manipulate the coolant bins as you want.I think that feature is very important,and has allowed me to control idle efficiently as well.

Personally, i would add a spark advance as well as retard feature,same as found on the motronic, so that when you use meth, or any kind of feature that can reduce the IATs and give better perfomance, the ECU would automatically climb to the higher advance. If you only have a retard and set to 0 the retard on the coolest IATs you get, then you are obligated to make a different map,via a switchable map feature to get any benefit from meth injection because with the addition of meth, you actually have a higher octane fuel + lower IATs(and therefore perhaps more advance can be added).

[guzior]

Hi.
Does anyone have a properly configured and well-functioning maps:
MAT/TPS Fuel Enrichement
MAT/TPS Ignition Retarda
RPM/MAP MAP Corr
??
and could share them?

[MWfire]

mattias:
i mean to afterstart enrichment

lugnuts:
i'm working in embed boost DC vs gear(like in 1.1.47), but with alterboost for N20,water or what do you want

[Arthur]

Hi all.

I.ve been offline to all vems things for a while. Now I see there has been changes a lot.

Being lazy (lot of text) and confused, could you guys awser me one small question. I've evolved from 1.0.73 megatune to 1.0.73 vemstune.

It looks very cool and got it working quickly. I tried 1.1.63 to but is seems like a gyand leep to mankind!

The firts thing I noticed that I lost 14 x 16 with spark and lambda map.



I have 1.3 bar boost, 60 - 2, 4cil, wasted spark and full seqential without camsinc.

I just want to use the better features from 1.1.6x And want to add the round gauche and egt.

So. What's the best software to confert to from 1.0.73 14 x 16.

[AVP]

if you read all the info on vems, you'll see that 14x16 table is only for VE now, and spark has 12x12 and lamda has 8x8. these are interpolating bins so you'll have to customise your previous tables to fit the new ones