AFR table stops at 7500... - Miata Turbo Forum - Boost cars, acquire cats.

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Old 09-04-2013, 05:58 PM   #1
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Default AFR table stops at 7500...

Very much a newbie at this and have a race on Sunday (3 days time)

I am concerned my AFR 1 table only goes to 7500.

I have a semi built motor and "believe" I can rev to 7800 or so.....

What happens when I go over the AFR table at 7500, is this an end of the world, doomsday scenario...?

How do I get the table to go to 8200 or therabouts for safety?

Also, can someone post up a afr table that I should use. The default has lowest afr at 12 (from memory).

From what I have read and seen in the past higher rpm/load should be 11.0 - 11.5 ish...does that sound right?
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Old 09-04-2013, 06:18 PM   #2
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Change 7500 to 8000. Scale the other cells as required.
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Old 09-04-2013, 06:32 PM   #3
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Click in the box and change the number if you want to. If it is scaled to 7500, everything above 7500 will be using the same values as 7500 cell anyway. But you might want more fuel.
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Old 09-04-2013, 07:38 PM   #4
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afr table is just a target table, not the actual ve table

meaning anything past the highest will maintain whatever the last value is

meaning it doesn't need to increase like your ve table does
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Old 09-04-2013, 10:07 PM   #5
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Sweet thank you.

My 1600 with a t28....I intend to run around 12 -14 psi boost. What is the consensus on AFR targets at the higher end of the rev/boost scale....I think I read AFR 11.5 but think I may have seen some people run down to 10.5 etc...

Thoughts..suggestions..?
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Old 09-04-2013, 10:08 PM   #6
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on pump gas you want 11.5-11.8 in significant boost
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Old 09-05-2013, 12:26 PM   #7
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11.2 up around 14psi on a t28.
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Old 09-05-2013, 04:09 PM   #8
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Thanks guys, rushing to get as much tuning and final prep work done on the car as possible.

Why does the to do list always seem so last minute, EVERY time!!

One day I'll be so prepared it'll be

In the meantime I trust Rev's base tune timing will be alright!
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Old 09-05-2013, 04:25 PM   #9
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post up screen shots of the tables and we can glance over them
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Old 09-05-2013, 05:18 PM   #10
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Quote:
Originally Posted by 18psi View Post
afr table is just a target table, not the actual ve table

Unless OP is using incorporate AFR, whereby the AFR target table is a part of the fueling equation.

But it matters not, as you pass the limit of the table, the numbers don't drop to zero, merely don't change for that axis.
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Old 09-06-2013, 01:26 AM   #11
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Actually in my newbieness I HAVE said to incorporate AFR (thats not how it is termed in the software but I think we are talking the same thing).

I presumed having an AFR gauge (MTX-L) and connecting it to the MS meant you should use that setting...

Right or wrong.....or personal taste?
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Old 09-06-2013, 01:29 AM   #12
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that is not at all what we're talking about.

we had a discussion about it a few months back. "incorporate afr" is an algorithm or something like that, that the MS uses to calculate your fueling. the afr target plays a bigger role in overall fueling vs using ve map exclusively

something like that. I'll let him describe it better because its fairly lengthy to fully explain

or you can search about it.

the MS "incorporates" your wideband at all times, so that's different.
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Old 09-06-2013, 05:55 AM   #13
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Yeah as above, incorporate AFR is a feature which takes the AFR target and adds it into the fuelling equation.

Once tuned you end up with a proper VE table, and if say you decide you want to run 11.5 instead of 11.8:1 at 200kpa through the rev range you'd just edit the AFR target table and hey presto with no further tuning that's the AFR that you'd be running.

Without incorporate AFR on the target table is just that, a target, and is used by the ECU during closed loop conditions and by TunerStudio/MegaLogViewer during VE analysis.
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Old 09-06-2013, 06:21 AM   #14
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Sadly most people dont understand teh difference between the VE table and the AFR table. ******* up one will blow your motor instantly, ******* up on the other one will blow your motor eventually. Take ur pick.
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Old 09-06-2013, 07:51 AM   #15
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My supposition was that the VE table is your ACTUAL fueling.

And that the AFR table is a target that the MS uses when "Incorporate AFR" is activated. It targets the AFR value in the table via an algorhythm that only WEIGHTS the VE table towards the AFR table + or - as required but doesn't run the vehicle exclusively by the AFR table over the VE table....

So even if the VE is not absolutely spot on having it aim towards the AFR table value will help achieve the more desired overall AFR (presuming that the AFR table is about right...)

am I on the right track...?
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Old 09-06-2013, 08:42 AM   #16
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Quote:
Originally Posted by mx5-kiwi View Post
My supposition was that the VE table is your ACTUAL fueling.

And that the AFR table is a target that the MS uses when "Incorporate AFR" is activated. It targets the AFR value in the table via an algorhythm that only WEIGHTS the VE table towards the AFR table + or - as required but doesn't run the vehicle exclusively by the AFR table over the VE table....

So even if the VE is not absolutely spot on having it aim towards the AFR table value will help achieve the more desired overall AFR (presuming that the AFR table is about right...)

am I on the right track...?
No

With incorporate AFR off, the VE table is the actual fuelling table + or - any temp and barometric based corrections.

The ECU will then use the target table to add/remove fuel assuming you have EGO authority enabled i.e. closed loop. This is best used not as a bandaid to a poorly tuned VE table, but to perfect the fueling due to minor atmostpheric changes etc.

With incorporate AFR turned on the above is also true i.e. closed loop operation, however the AFR targets are also a part of the fueling equation, so if you want to change the AFR of a part of your tune, you literally change the numbers in the target table and hey presto the actual AFR will have changed with no tuning or changes to the VE table required.

Incorporate AFR off:

PulseWidth = ReqFuel * VE(rpm,map) * MAP * GammaE

Incorporate AFR on:

PulseWidth = ReqFuel * VE(rpm,map) * MAP * stoich / targetAFR(rpm,map) * GammaE
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Old 09-06-2013, 09:21 AM   #17
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Exactly. So if you're not tuned yet, I'd probably suggest you do stick with "incorporate" and tune it like that. It will make things easier later down the road.
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Old 09-06-2013, 09:41 AM   #18
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Quote:
Originally Posted by mx5-kiwi View Post
Actually in my newbieness I HAVE said to incorporate AFR (thats not how it is termed in the software but I think we are talking the same thing).
that's not newbieness.
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Old 09-07-2013, 01:41 AM   #19
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right o, flame away.
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