$A1: Fuel calculations above 4000 rpm

[LZeppelin513]

I realize this has been discussed before but was not able to find what i was looking for from searches. Above 4000 RPMs is the corresponding base VE added to the last value in the Main VE (4000 rpm)? So, is the base VE table the only way to modify fuel above 4000 rpm?

Thanks

[robertisaar]

when exceeding any limit on a table, the last value in the correct row/column will be used.

example: 6000RPM and 95kPa, you'll get the 4000RPM/95kPa cell + the adder table.

it's one of the many things i hate about stock A1.

[LZeppelin513]

OK thanks, and the adder table is just another name for the base VE table, correct?

This may be a dumb question; Would there be a reason not to just set all values bellow 4000 rpm in the Base VE table to zero and just use the main VE and idle VE to account for those?

[robertisaar]

correct

and

correct. that's actually what i've done many times. well, until i learned how to make my own tables to get away from the method GM created.

[LZeppelin513]

I like the way your nast1 code is set up much more than $A1. I have a pretty good nast1 tune but for some reason i am getting crap fuel economy. I am switching over to $A1 for a bit to to see if I can get any better fuel economy. The lower resolution of $A1 may help me get a better handle on it all.

[3400-95-Modified]

correct

and

correct. that's actually what i've done many times. well, until i learned how to make my own tables to get away from the method GM created.

A nice feature on my Legacy tuning is they allow you to re-scale the tables to whatever you want... so you can adjust them to fit your peak engine load or peak RPM you'll run... it's nice to have.

[robertisaar]

not sure what kind of processor that PCM would be using to do that, but the megasquirt does something similar.

but to impliment that capability with a 68HC11 would be..... painful, since the entire 3D table lookup subroutine would have to be rewritten.

i got around this desire by having massive tables that span 400-8400RPM, 400-2000 in 100RPM increments, then from 2000-8400 in 200RPM increments..... to be honest, it's way overkill and i'm going to have to tone it down a bit, otherwise there are 833 cells to fill in for main spark, 833 cells to fill in for main VE.....

[LZeppelin513]

In my main VE table at 4000 RPM, 100 kpa is at 99 ish. I am going lean above 4000 RPMs. Before I do run again at high RPM and blow up my engine I though I would ask a question.

Will increasing the adder table at say, 4400 RPMS which puts my total VE (main from 4000 (which is 99 ish) + adder) to over 100 total. Because no value in a table is actually over 100, will this work and I will get more fuel to 4400 RPM in this case?

[robertisaar]

no.

if the adder + main (or idle) adds up to 100 or more, it only is considered 100 by the ECM, regardless of RPM.