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-   -   Fuel table question (high load low kpa) (https://www.miataturbo.net/megasquirt-18/fuel-table-question-high-load-low-kpa-66780/)

andrew 06-25-2012 03:01 PM

Fuel table question (high load low kpa)
 
4 Attachment(s)
Hi,

I just used travisb's fuel table smoothing calculator. Its great. I noticed that when I run auto tune it keeps adding fuel in in the lowest kpa cells when the engine revs are falling (like slowing down slowly) or when changing gear.

I presume I am missing something in my settings as the car drives great, hits its my target AFR's all the time. I just dont know why the engine wants big fuel table no.s when there is no load. Table attached. I have lowered these no.s manually but autotune will look for no.s around 100.

Any suggestions?

Braineack 06-25-2012 03:02 PM

i cant imagine it drives great with that fuel table. just imagine how great it will feel when you actually fix your issue of that horrid table...

hustler 06-25-2012 03:04 PM

Those cells are hard to tune without a dyno. Put the car in 2nd and roll around at 50mph and tune them manually. VEAL has a hard time understanding what to do when transitioning to over-run.

Braineack 06-25-2012 03:09 PM

things i noticed:

you have 265cc injectors but a req_fuel for 600-800cc injectors.
youre using include AFRtarget
your ignition table is very retarded

andrew 06-25-2012 04:02 PM


Originally Posted by Braineack (Post 895169)
things i noticed:

you have 265cc injectors but a req_fuel for 600-800cc injectors.
youre using include AFRtarget
your ignition table is very retarded

I need to update my sig, I have 550cc EV14 in now.
My VE values are lower in other areas with same AFRtarget, how is this a problem?
I had the spark table tuned by a tuner on a dyno. He said it was knocking and I asked him to set it conservative. I could be wrong, but I thought the spark map is all relative to the ignition offset angle set in the trigger wizard.

andrew 06-25-2012 04:15 PM


Originally Posted by Braineack (Post 895166)
i cant imagine it drives great with that fuel table. just imagine how great it will feel when you actually fix your issue of that horrid table...

I have manually smoothed the table but it feels the same to drive. This is the fuel table autotune has given me through 5 hours + of tuning and manual smoothing going from easy to very hard. I presume its a bit lumpy in the mid revs/load due to the change in target AFR. The very low revs high kpa areas are not tuned as the car never goes there. I have to say I trust what autotune is giving me, the VE numbers it suggests give me the AFR ratios I want. Its also not tuned above 155 kpa

Oni 06-25-2012 11:17 PM

WUE numers also dont have a 100% value, i beleive this means u will always be in WUE with the last value u have (106%). Can someone smart confirm this please :).

Zaphod 06-26-2012 02:36 AM


Originally Posted by Braineack (Post 895169)
things i noticed:
youre using include AFRtarget

That in my understanding is not a bad thing to do (as I said before) - you can change the AFR target table without big changes to the VEtable (because the AFR is included in the fueling calculation.

Braineack 06-26-2012 09:03 AM


Originally Posted by Zaphod (Post 895427)
That in my understanding is not a bad thing to do (as I said before) - you can change the AFR target table without big changes to the VEtable (because the AFR is included in the fueling calculation.


sure, but do it AFTER you tune the VE table.

Zaphod 06-26-2012 09:20 AM


Originally Posted by Braineack (Post 895471)
sure, but do it AFTER you tune the VE table.

then you will have to retune the VEtable again, afaik..

andrew 06-26-2012 04:33 PM


Originally Posted by Oni (Post 895371)
WUE numers also dont have a 100% value, i beleive this means u will always be in WUE with the last value u have (106%). Can someone smart confirm this please :).

I brought the WUE down from 106 to 100%. This messed up the fuel table big time. I started the autotune it again, but it was miles off and autotune didn't seem to make changes to the fuel table, so I reverted back to the old tune as I am happy with it.


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