"VE as % ( FL1) Corrected

[CDeeZ]

Recently, I noticed that while using the $42-1227747-V4.xdf that there are TWO VE1 tables.

When you mouse over the two tables in the parameter tree in TPRT, the regular VE1 table has a comment that says "This is the table that everyone has been using for years and is not correct. Use VE as % (FL1) Corrected".

The values are the exact same in either table, I don't get what is going on here???

[EagleMark]

Someone made a mistake years ago when making the mask. But the value in each cell is correct so it works. If you look at the hack of $42 the RPM and MAP are reversed. Both tables will show the values correctly. If you make a change in one it will show in the other.

[CDeeZ]

Hm, I see. Well my regular VE1 table has RPM in the rows and MAP in the columns... VE2 also has RPM in the rows so I guess I'll continue to use the regular VE1 table for consistency.

[EagleMark]

Doesn't matter, if you change a cell in one it will change in other. The only reason I left the first one is because it is what everyone is used to and works with spreadsheets available.

If your still using values in VE2 then you can't add fuel to many places that need it until you raise fuel pressure. If you add VE2 to VE1 you will have many numbers that come out to over 100. It's a GM mistake. ECM will truncate to 100, or I think 99.6. Either way this is static and not good and will not produce good results. Add all your VE2 numbers to VE1 and tune off one table and keep VE below 95, lower is better.

There is barely enough fuel available for a stock motor at 13PSI fuel pressure and no way to add fuel in either table. Can not go over 100%, 95% starts to go static (open all the time).

[CDeeZ]

Add ALL of VE2 to VE1 and zero out VE2??? I see what you're saying about using one table, but how is that possible since VE2 is always added to VE1 and, at least I thought this: you need something in VE2 so you can take fuel out if necessary at those higher RPMS??

I'm not sure how to shuffle the numbers up here?

[EagleMark]

VE2 says 39.06 at 400 RPM, so add 39.6 to all cells in 400 RPM Row or Column, rinse and repeat for all. 0 out all VE2. Above 3200 RPM will use last value in VE1 Main Table.

If you do this you will see numbers higher then 100, which is not possible to have more then 100%. When you Commit or Save then reopen you will see TP changed the number over 100 to 99.6.

[RobertISaar]

a VE of 100% isn't static.... an injector duty cycle of 100% is though.

[EagleMark]

OK misworded, but still can not have more then 100% in VE tables...

[RobertISaar]

and for more hair splitting.....

you COULD.... if you adapted the mask to support it. but i can't think of any that support it natively.... well, the 93-95 3100/3.4RWD setup allows it, but it is also in 16 bit instead of 8.

[EagleMark]

Really? Hmmmm... I wonder.... dam I'm trying to avoid learning hacking and writing code as I have to much to do, but keep learning slowly out of neccessity. I can only dream it would be as easy as changing a multiplier? Instead of 1 make it .75, poof 25% more fuel.

Most of these 7747 I have done that's about all they are short, Injector Duty Cycle is no where near maxed but VE is. So more pressure!

[RobertISaar]

i can't speak for the C3 setups, since their instruction set is slightly different than the processor used in the P4/P6 units, but it would be dead simple to cut the resolution of the VE tables in half to double their range.... then again, the same thing is accomplished by moving the BPC around.

and it's not like more pressure is a bad thing. ;)

[EagleMark]

Tell me more! What would I look for?

These old things have BPW and changing it from a calculated number based on pressure has horrible untunable results, that I have found anyway? Bigger = rich bottom lean top. Smaller = lean bottom rich top. Both equal never getting VE correct? I gave up and stuck to what works. MORE PRESSURE!

[RobertISaar]

perhaps i'm not used to the TBI portion of it, but A1 and it's relatives all use a BPC the same way the 7747 does. it's a fudge, at best. it's not a real injector flowrate or real cylinder size value, it's more or less a multiplier to begin with.

basically, we get our highest expected VE's to be in the 90 or less range in case of needing to give a little more fuel. that gives the most amount of table resolution. ideally..... BPC would be tweaked to where the VE table in the tune is identical to one actually calculated from airflow sensors measuing the engine's real breathing capability. but, it's not that important.

[CDeeZ]

VE2 says 39.06 at 400 RPM, so add 39.6 to all cells in 400 RPM Row or Column, rinse and repeat for all. 0 out all VE2. Above 3200 RPM will use last value in VE1 Main Table.

If you do this you will see numbers higher then 100, which is not possible to have more then 100%. When you Commit or Save then reopen you will see TP changed the number over 100 to 99.6.

Are you saying that if I add all of the VE2 values into the VE1 table at the corresponding RPMs, that I can zero out the ENTIRE VE2 table ALL the way to 6400 RPM???? The last range of RPM cells in VE1 (3200 RPM) can be used to tune ALL RPMs beyond 3200 WITHOUT the use of the VE2??? I don't understand how that works. I know that GM used the 2D VE2 table becuase it saved space and reduced processing time, but I'm still failing to see this one.

How do you use the last entry in VE1 (3200RPM) to tune the VE needed for say, 4500 RPM?? It seems like once you get your 3200 RPM range of cells dialed in on VE1, that if you came back to tune for 4500 RPM using the last range of cells that it would mess up your VE for the 3200 RPM range...

I'm sorry if I'm making something simple into a mess but I'm just trying to understand the why.

[EagleMark]

Yup! I was reluctent to try it but a good tuner talked me into it and I never looked back, always works fine. There's no way you can get above 3200 RPM without low vacuum, high MAP in the VE table which should be a 90 plus reading and probably PE. It takes last known VE from Table one and goes with it, if you look into it, it's more fuel then using stock VE2 because VE2 starts to take away fuel and limits power and RPM, look at drop of VE at 4000 RPM IIRC. Some say you need to leave value in 0 RPM VE2 but I have gone with 0 there as well.