Tuning Formula

[Spectre22]

Ve tuning formula to help people when tuning there Ve maps.   New VE = Old VE(Current AFR / Desired AFR)


Example lets say at 2500 rps with 7 hg (map reading) the AFR is 13.5 And you would like it to be 14.7 and you current VE setting at that Rpm and map reading is 76.0 you would take 76.0(13.5/14.7) and would give you a new VE of 69.8 which should put you at the 14.7 AFR you were looking for at that Rpm and Map reading.

[citymunky]

This is from the old DSMap's forum that I still had open in one of my TAB's

Hope this isn't a repeat.

newVE% = oldVE% * (old AFR / desired AFR)

Works shockingly well.

Here's a ex.

NewVE% = 85.2 * (11.0 /14.7)

NewVE% = 85.3 * (0.748)

NewVE%=  63.8

It seems like magic, but you are basically figuring out how much more fuel you need as a percentage and increasing accordingly.

Actually got it from the megasquirt manual

http://www.megamanual.com/ms2/tune.htm#afr

Instead of 14.7 you'd use whatever AFR you are at. Actually, there is a ton of good info on that page about tuning.

[Ravewolf]

Ok...so is this using a logger, or going off the wideband? And on the example, why is it 85.2 then 85.3? How do you add this up when lets say for example:

6500
25.1 psi
10.6afr and wanting 12.4afr?

  (10.6/12.4)*85.2? which when I do it right equals out to 72.83?

Would I input this number on the block where the rpm and psi meet? Or on the % bar? And how do you set the hard and soft ve? I'm trying to learn this the right way instead of shooting in the dark like I was before.

[1990talonfast]

Ok...so is this using a logger, or going off the wideband? And on the example, why is it 85.2 then 85.3? How do you add this up when lets say for example:

6500
25.1 psi
10.6afr and wanting 12.4afr?

  (10.6/12.4)*85.2? which when I do it right equals out to 72.83?

Would I input this number on the block where the rpm and psi meet? Or on the % bar? And how do you set the hard and soft ve? I'm trying to learn this the right way instead of shooting in the dark like I was before.

I also would like to know this.

[jrohner]

Ve tuning formula to help people when tuning there Ve maps.   New VE = Old VE(Current AFR / Desired AFR)


Example lets say at 2500 rps with 7 hg (map reading) the AFR is 13.5 And you would like it to be 14.7 and you current VE setting at that Rpm and map reading is 76.0 you would take 76.0(13.5/14.7) and would give you a new VE of 69.8 which should put you at the 14.7 AFR you were looking for at that Rpm and Map reading.

This is basically what I do for tuning my 2G.  I setup a value to log, so my log basically tells me exactly what to change in the VE.  I also do it for MAF-based tuning as well for tuning MAF compensation.

[Kapok6]

OK, so I just want to make sure I understand this...I don't make the soft VE match what I need, I make the hard VE?

Target is 11.07 AFR

13.8psi
10.37afr
current Soft VE % is 125
 So would I go (10.37/11.07)*125 giving me a new soft VE of 117

Or am I supposed to look at it like this:

13.8psi
5375rpm
10.37afr
13.8psi @ 5375rpm on hard VE table is 104 (Compensation View)

so (10.37/11.07)*104 giving me a hard VE value of 97.42
If this is the correct way, should I be going off the compensation view or not off the compensation view?

Which way is correct?

[hakcenter]

OK, so I just want to make sure I understand this...I don't make the soft VE match what I need, I make the hard VE?

Target is 11.07 AFR

13.8psi
10.37afr
current Soft VE % is 125
 So would I go (10.37/11.07)*125 giving me a new soft VE of 117

Or am I supposed to look at it like this:

13.8psi
5375rpm
10.37afr
13.8psi @ 5375rpm on hard VE table is 104 (Compensation View)

so (10.37/11.07)*104 giving me a hard VE value of 97.42
If this is the correct way, should I be going off the compensation view or not off the compensation view?

Which way is correct?

The ve comp table, is a row multiplier.. so if you notice through the rpm band a certain map pressure is the same, yet the afr is lean or rich.. you would use the comp ve to scale it down, then fine tune on the full 2d table.

[Kapok6]

OK, so I just want to make sure I understand this...I don't make the soft VE match what I need, I make the hard VE?

Target is 11.07 AFR

13.8psi
10.37afr
current Soft VE % is 125
 So would I go (10.37/11.07)*125 giving me a new soft VE of 117

Or am I supposed to look at it like this:

13.8psi
5375rpm
10.37afr
13.8psi @ 5375rpm on hard VE table is 104 (Compensation View)

so (10.37/11.07)*104 giving me a hard VE value of 97.42
If this is the correct way, should I be going off the compensation view or not off the compensation view?

Which way is correct?

The ve comp table, is a row multiplier.. so if you notice through the rpm band a certain map pressure is the same, yet the afr is lean or rich.. you would use the comp ve to scale it down, then fine tune on the full 2d table.

This is what sucks; it's very hard for me to understand this without someone physically showing me.

So that being said, I guess the better question for me to ask is, "where to I change the VE# to properly utilize the formula above?"

Would it help if I posted my latest DS.2 and log and someone takes som screen shots and physically shows what's being done?

I apologize for my stupidity here.  I have always been able to learn better when being physically shown than by reading.

[big_d]

Let me try.
Say for instance your peak boost is 14lbs (like your example) and you reach full boost at 3500RPMs... Now you notice at 5375 that your very rich (10.37 when your target was 11.07)...  Right away, you think "hey I'll adjust the cells at 5000 and 5500 around the 14lbs row to take care of my richness.  BUT WAIT! the car was actually between 10.20 and 10.40 for the entire time I was at full boost.  SO instead of adjusting those few VE cells, you can actually go to the column on the left (the comp VE column) and adjust the cell that corresponds to 14lbs (full boost).  The column is there for convenience.  It makes tuning at particular vacuum/pressure levels easier for you to dial in across the entire RPM range.

The first car I tuned on Jackal (a few years ago), I never even used this column.  Now that I'm a bit wiser, I use this column for the first pull or two, then begin adjusting individual cells.

Hope this helps.  I could probably do a write-up if need be.

[Kapok6]

Thats what I thought, I adjust the soft VE at the boost of Vac levels that need adjusted.  I shouldn't really be touching the Hard VE.  So that being said, when using the tuning formula above, the only VE # I look at and adjust is the soft VE to the left correct?  Just want to make sure I have this right instead of doing this wrong and blowing my car up.

[JLR11]

Not to throw too much of a curve ball at you guys but I actually set my "compensated" multiplier to 100% in all columns (for the most part).  Both my VE tables "compensated & non-compensated" read the same which actually made things easier for me. I did have to increase the percentages in the "multiplier" column of the higher boost areas because you can only hit 127.5% max adjustment in the individual cells with the mulitiplier set at 100%.
Also note that when you use the tuning formula you want to use the non-compensated view values which are your true VE values, this will also hold true if using Snapc33's tuning sheet when inputting the VE values. I highly recommend using his tuning sheet as it will make tuning much easier/faster.