Map Air fuel ratio base

VersaTuner for Mazda RX-8
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tophe88
Posts: 29
Joined: May 6th, 2022, 8:31 am

Map Air fuel ratio base

Post by tophe88 »

Hello

I would like what is the Map Air fuel ratio base ?

What is the difference between with other map of ratio ?

Regards
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wcs
Posts: 61
Joined: May 12th, 2021, 12:46 am

Re: Map Air fuel ratio base

Post by wcs »

I'm not sure I entirely understand your question.

If you want to see the base map, I believe you can download the free version and see the base AFR maps.

As far as comparison, VT will show you the comparison values to any map you choose.
The difference between the other maps well depends on entirely the map you want to see?
Which map is it you want to compare?
VT_AFR_Comparison.jpg
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tophe88
Posts: 29
Joined: May 6th, 2022, 8:31 am

Re: Map Air fuel ratio base

Post by tophe88 »

i ask the Air fuel map ratio base :) under AFR map 3.

How you get the value in AFR ? i have lambda valu on my ??? :bigeyepop
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wcs
Posts: 61
Joined: May 12th, 2021, 12:46 am

Re: Map Air fuel ratio base

Post by wcs »

Air Fuel Ratio Base
(sorry about the confusion)

That's a good question. I am not entirely sure.
I'm guessing it is suppose to have something to do with the amount of air needed to achieve the complete combustion of a given quantity of a fuel and type of fuel.
Why it is at 13.85016 for a gasoline engine ... I do not know, perhaps to set the ECU stoichiometric level richer than than the actual calculated gasoline stoichiometric value of 14.7
(just guessing)
VT_AFR Fuel Ratio Base.jpg
VT_AFR Fuel Ratio Base.jpg (100.8 KiB) Viewed 4052 times


Switching Lambda to AFR
Switch Lambda to AFR.jpg
Switch Lambda to AFR.jpg (166.78 KiB) Viewed 4053 times
tophe88
Posts: 29
Joined: May 6th, 2022, 8:31 am

Re: Map Air fuel ratio base

Post by tophe88 »

Thank you for this :) Its better for read AFR.

Yes i have the same question why is not 14.7, you are maybe good.

Have you already tune for e85 rx8 ?



And how i can save a map under other name file please ?
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wcs
Posts: 61
Joined: May 12th, 2021, 12:46 am

Re: Map Air fuel ratio base

Post by wcs »

No I have not tried to tune for E85.
E85 isn't very common or cheaper where I'm located in Canada.

To save map under different name file

#1
VT_SaveTuneAs-1.jpg
VT_SaveTuneAs-1.jpg (65.95 KiB) Viewed 4042 times


#2 Then do this
VT_SaveTuneAs-2.jpg
VT_SaveTuneAs-2.jpg (99.45 KiB) Viewed 4042 times
tophe88
Posts: 29
Joined: May 6th, 2022, 8:31 am

Re: Map Air fuel ratio base

Post by tophe88 »

thanks for this ! :)

If i want pass to e85, need to update AFR ratio base ? or only other map ?

And do you know, how to increase the STFT by tuning map ?
Please
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wcs
Posts: 61
Joined: May 12th, 2021, 12:46 am

Re: Map Air fuel ratio base

Post by wcs »

Sorry I'm not really well learned with E85 tuning.
I'm guessing you'll need to increase all the Acceleration enrichment maps, those should help with throttle tip-in. (STFT)

I believe you'll need to increase all the Air Fuel Ratio map because E85 has a different Stoichiometric value than gasoline.

As far as changing the "Air Fuel Ratio Base" map, I've never had to touch that value.
I would suggest running a test, drive around using the stock tune and collect a data log.
Then change on the "Air Fuel Ratio Base" value to 13 or 12.5 and do the same drive logging the drive.
And compare the two logs. I suggest you drive easy to avoid any issues.

Mechanically you may also need a larger fuel pump and injectors to handle the increase demand for fuel.

Sorry I can't be more specific I really haven't spent anytime looking in to E85 tuning.
Good luck.
Keep us posted.
I'll try and help where I can (if I can)

:beertoast
tophe88
Posts: 29
Joined: May 6th, 2022, 8:31 am

Re: Map Air fuel ratio base

Post by tophe88 »

I'm guessing you'll need to increase all the Acceleration enrichment maps, those should help with throttle tip-in. (STFT)

How is work ? The indicate value is the percentage of lambda that the ECU can handle ?

Because by default is 25% when i check my STFT
But if i add 25% to this value is really lean ^^

Thank you for your help, i appreciate
Walle
Posts: 51
Joined: August 29th, 2021, 7:27 pm

Re: Map Air fuel ratio base

Post by Walle »

the target afr should not be changed!
ecu stores lambda value, and lambda sensor measures, well lambda. it cares nothing about the fuel it uses in those tables.

I would suspect the original map in question of 13.8 is the estimation of how much fuel it needs compared to air in order to achieve lambda=1.

so that could well be global modifier that one could change in order to use e85...

How I suspect the map is used.

rpm and load -> afr target map -> 0.9 for example.
maf * lambda * air fuel ratio base -> injector flow map / duty cicle.
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