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Author Topic: krkte %-Ratio adjustment for e85  (Read 14952 times)
up50lut3
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« on: July 22, 2018, 02:12:44 PM »

hey all,

simple question( may not be such a simple answer) but i have been playing with e85 recently and basically have come down to the conclusion of ( in this one area of topic) krkte for fuel instead of anything else( like fkkvs for example, which is atm set to all 1's)

as of right now i just used lemmeiwinks to add some fueling(+ 14. % in the primary channel) and now have my STFT and LTFT's at -1.6 and -2.3 respectably( with around .81 to .83 lambda at WOT to redline ( without lemmewinks adjustment about +15 on both)

so i was wondering if anyone had any insight as to how to go about adjusting krkte for the change? is there a given formula? i understand how to calculate krkte as a base to get started with injector change, but not much as far as adjusting for so much added fueling.

any insight would be much appreciated thank you!
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nyet
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« Reply #1 on: July 22, 2018, 07:02:13 PM »

Never use lemmi
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woj
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« Reply #2 on: July 23, 2018, 04:34:19 AM »

My KRKTE scaler (you just multiply) for E85 is 1.403. This is under the assumption that the ECU was originally tuned for E5, which is the norm in Europe, not sure about the rest of the world.
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overspeed
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« Reply #3 on: July 23, 2018, 10:00:58 AM »

A little formula, adapted from FR

KRKTE [ms/%] =  Airdensity x Vhzyl / (0,00167 x AFR x Kfuel xQstat)


airDensity = 1.293 g/dmˆ3 Air density (0 °C and 1013hPa)
Vhzyl [dmˆ3] Piston displacement of a cylinder in dmˆ3
Qstat [g/min] Valve constant for n-heptane
Kfuel = density correction for gasoline/ exotic fuel based on n-Heptane
AFR =  Air/Fuel constant at combustion for Lambda = 1.0
Normmk = 0.001667 min/ms Adaptation of units

Note that you must calculate Kfuel from density relaed to n-Heptane.

I use it with sucess in Brazil when tunin E100, E05, etc.

In the past VW calebrated FKKVS to avoid changing KRKTE when Brazil changed to E22 (now it is E27 on regular fuel)


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up50lut3
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« Reply #4 on: July 24, 2018, 07:22:41 AM »

thanks

let me ask this a different way..... SIMply, how do i adjust krkte based on LTFT's?

just that simple part... dont worry about fuels or anything...thanks!
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nyet
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« Reply #5 on: July 24, 2018, 07:30:34 AM »

Just follow it exactly (assuming your TVUB is correct).

Add or remove x% from KRTKE depending on LTFT.
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lepatron972
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« Reply #6 on: July 25, 2018, 04:31:28 AM »

Just follow it exactly (assuming your TVUB is correct).

Add or remove x% from KRTKE depending on LTFT.

Hi, just admit that we have changed the injectors, we calculate krkte, but how to find tuvb, I did not have when buying the injectors



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lepatron972
nyet
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« Reply #7 on: July 25, 2018, 07:48:30 AM »

If you do not know the correct TVUB you're in trouble.
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lepatron972
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« Reply #8 on: July 25, 2018, 07:52:21 AM »

If you do not know the correct TVUB you're in trouble.

no I do not have it, for cons I have the flow for 2.5ms
so I calculated for 1g of fuel at 12.4V
Do you think I'm far from it with this method?


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up50lut3
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« Reply #9 on: July 27, 2018, 06:12:00 PM »

Just follow it exactly (assuming your TVUB is correct).

Add or remove x% from KRTKE depending on LTFT.

Thank You! im pretty sure it is. cars been within 3% total( stft and ltft) deviation from zero fro about 1 yr now on 93 octane.. just changed to e85 and been making adjustments accordingy just never new how to adjust krkte without using the gueesing game after the ballpark values
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up50lut3
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« Reply #10 on: July 30, 2018, 12:33:23 AM »

no I do not have it, for cons I have the flow for 2.5ms
so I calculated for 1g of fuel at 12.4V
Do you think I'm far from it with this method?

tvub is something that you can( base off) get from the datasheets on your injectors.

its not something you can "ballpark" really

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lepatron972
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« Reply #11 on: July 30, 2018, 12:42:10 AM »

TUVB is the reference time for 1g of fuel if I am not mistaken, I say this because we have the value TIMIN which corresponds to the minimum quantity for lambda 1


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lepatron972
nyet
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« Reply #12 on: July 30, 2018, 08:11:24 AM »

TUVB is the reference time for 1g of fuel if I am not mistaken, I say this because we have the value TIMIN which corresponds to the minimum quantity for lambda 1


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no TUVB is injector latency.

And your definition of TIMIN is wrong as well.
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lepatron972
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« Reply #13 on: July 30, 2018, 08:19:43 AM »

no TUVB is injector latency.

And your definition of TIMIN is wrong as well.
this can be computed an example it is in french but I found this




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lepatron972
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« Reply #14 on: July 30, 2018, 08:28:53 AM »

Also it is TVUB not TUVB.
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