Tuning a 93 3.4 Firebird

[tkoforpresident]

the ECU interpolates a weighted value based on the VE tables RPM and MAP. spark is the same way.

so if it's at 1175 RPM and 49.5kPa, the value will be VERY close to the 1200 and 50kPa cell value, but it will be modified by the 800 and 45kPa cell.

sounds good to me. thanks for the insight!

[tkoforpresident]

Now that i have my next chip burned i'll be datalogging again in the next couple days. I'm going to try to do it for a while to get as much data as possible and try to log some higher rpms multiple times (not driving, just stationary) to get some good data.

question: is there an idle VE table we can work on just for idle or is the "main VE" table we're working on now an all encompassing type table?

question: I'm getting my data while the car is stationary. Once i start to log with it driving will the VE tables need to be gone over again or are we getting most of it right now with what i'm doing?

thanks

[robertisaar]

there is actually an idle VE table, and if it doesn't have the same VE values as the main one, you will be chasing your tail trying to tune fuel. there are also values in between, such as 1000 RPM, which you won't find in the main table. you will want to put that value exactly halfway between the value above it and the value below it. the graphing function works great here, to remove any possible error from math.

i've tried to disable the idle table through messing with constants, but no-go. maybe i didn't play with it enough, but i couldn't get anything out of it. and i really wouldn't go over 3-4K RPM in neutral... it's not that good for the motor to do that with absolutely no load on it.

[tkoforpresident]

there is actually an idle VE table, and if it doesn't have the same VE values as the main one, you will be chasing your tail trying to tune fuel. there are also values in between, such as 1000 RPM, which you won't find in the main table. you will want to put that value exactly halfway between the value above it and the value below it. the graphing function works great here, to remove any possible error from math.

i've tried to disable the idle table through messing with constants, but no-go. maybe i didn't play with it enough, but i couldn't get anything out of it. and i really wouldn't go over 3-4K RPM in neutral... it's not that good for the motor to do that with absolutely no load on it.

so your saying that there is an idle table but that it should only be filled in once the main VE table is more or less completed?

You will have to show me (when the time comes) how to transfer the data over to the idle VE table using this "graphic function" that i know nothing about.
and i won't go any higher than 3,000 rpm. I don't like going any higher than that at stationary.

[robertisaar]

idle table need to be changed at the same time the main one does.

[tkoforpresident]

idle table need to be changed at the same time the main one does.

wait, what?


so are you telling me that the adjustments i just made to my VE are only partially complete??

[robertisaar]

that's the easy way of putting it.... oops, i guess? it's actually a good thing you brought it up.

BTW: another v5 bonus: my spreadsheet does the idle VE table for you.

[tkoforpresident]

that's the easy way of putting it.... oops, i guess? it's actually a good thing you brought it up.

BTW: another v5 bonus: my spreadsheet does the idle VE table for you.

lol..... i don't want to hear the word "oops" if i can help it. I do "oops" enough myself.

heres the "modified" Main VE table on the left, and the newly found "idle VE" table on the right.



So how do i do this??

[robertisaar]

most of it is copy/paste from the main VE table to the idle table, but the 1000 and 1400 RPM columns will need to be numbers that are the exact midpoint between 800 and 1200 for 1000, and 1200 and 1600 for 1400.

easiest way for that is to hit the view graph button and drag the points on the graph to where they look correct.

easy enough?

[tkoforpresident]

most of it is copy/paste from the main VE table to the idle table, but the 1000 and 1400 RPM columns will need to be numbers that are the exact midpoint between 800 and 1200 for 1000, and 1200 and 1600 for 1400.

easiest way for that is to hit the view graph button and drag the points on the graph to where they look correct.

easy enough?

i don't get it though. Some of the values that are on the Main VE table (pre modification) are not the same, even though they are the same RPM and Map Kpa.

For instance, the Idle VE says 24.71 for the 600rpm/20kpa cell, but my Main VE (unchanged) says 17.25 in the same cell (600rpm@20kpa)

so which ones do we use? i'm confused. Do i just replace the whole graph with that from the other one? I would have assumed they would have been exactly the same as one another if they were at the same rpm &kpa

[robertisaar]

chalk it up to GM and their strange way of doing things...

i just use the main and completely replace everything in idle VE.

[tkoforpresident]

hahah wow, ok. I will do as you say.

just to verify the correct way to do this...

for the cells that are inbetween ( 1,000 rpm for example) i can take the 800 rpm cell and 1200 rpm cell for the same kpa row and add them together then divide by 2 and that will give me the correct # for 1,000 rpm?

and then all the other ones that i know i can just transfer over....

[robertisaar]

I will do as you say.

AWESOME! i have a second WIFE!

that's the "math intensive" way of doing it, but yes, that would work perfectly.

[tkoforpresident]

AWESOME! i have a second WIFE!

that's the "math intensive" way of doing it, but yes, that would work perfectly.

more of an understudy than a wife... but i've been called worse.

I'll go ahead and REDO my VE tables now that i know how to do it right...

Thanks again!

[tkoforpresident]

so once i start to datalog while driving will i have to redo my VE tables again?