Board logo

Another megasquirt question
clairetoo - 17/11/08 at 09:31 PM

I somehow got my Lc1 reading consistently on the return trip from Exeter on Sunday , so I set it to run on autotune - with spectacular result's
It was doing about 27 mpg on the way down , and with autotune doing it's thing I got close to 40 mpg coming home
But......I just had a look at the target AFR table , and it's 8x8 , whereas the fuel and ignition tables are 12x12 - and I cant help thinking that it would work even better with the same scaling on all table's .
I know it is possible to re-size the table's , but I have no idea how , and I cant find anything in megatune to give me a clue - is there anybody out there who can point me in the right direction ?


paulf - 17/11/08 at 09:38 PM

I think the target table is fixed as an 8x8 , you just need to set the spread to cover your cruising and full throttle areas .
Paul.


flak monkey - 17/11/08 at 09:45 PM

quote:
Originally posted by paulf
I think the target table is fixed as an 8x8 , you just need to set the spread to cover your cruising and full throttle areas .
Paul.


Thats also my understanding, am willing to know if there is a way though!

Great results Claire! I am hoping for a significant fuel economy improvement from the pinto after I have megasquirt up and running!

David


martyn_16v - 17/11/08 at 09:49 PM

As mentioned, you can't make MS use 12x12 target AFR tables.

It's not quite as bad as it seems at first though. You don't really want closed loop lambda control active across the entire operating range of the engine. At WOT and high rpm it's not the greatest idea (sensors generally don't react fast enough to be really useful, and potentially catastrophic in the event of a sensor failure), and it often doesn't work very well at idle either. Most people have a row on the fuel/ignition tables for overrun, which again doesn't need an AFR target. So once you've got rid of all the areas where closed loop won't be used, the 8x8 target AFR table is generally just about big enough

edit to add: oh, and you'll probably find that you just won't need even 8 rpm columns in the AFR table anyway. The AFR targets are pretty constant for a given load for any RPM in the mid range. My target AFR tables usually end up having at least some rows with the same figure all the way across

[Edited on 17/11/08 by martyn_16v]


clairetoo - 17/11/08 at 10:00 PM

sooooooooo................if I re-number the scale to ignore closed throttle , and the upper throttle range , as well as the higher rev range - will that give me what I am after (better definition aroung the usable range) ?


flak monkey - 17/11/08 at 10:13 PM

Yes, thats the theory.....


clairetoo - 17/11/08 at 10:39 PM

quote:
Originally posted by flak monkey
Yes, thats the theory.....

Cheers


omega 24 v6 - 17/11/08 at 11:10 PM

Be aware that when you re jig your table the ve numbers will not move with it IIRC
i.e all the figures will stay in the 8X8 table but your map (or tps ) will change.