tuning for E85

[RunnWS7]

I´m wondering if anyone here has converted there car to E85?

I´m running my car on 25% E85 and are increasing the % every time i fill my tank.

I am adjusting my VE table but i dont think i can go past 60% since with E85 the engine needs more fuel and my stock injectors are to small.

[possum22]

This tread on ls1tech.com may interest you.
http://www.ls1tech.com/forums/showthread.php?t=378268

[RunnWS7]

My name is D_Run on ls1tech i had the second post in that thread.

[Runn WS7]

Has anyone converted to E85?

I run my car on a 50-50 mix right now without any problems. I have added to the VE-table thats all. Looking for bigger injectors before i move up to 100% E85.

Does anyone have info of the Flex fuel vortec´s tuning... mainly what the PCM changes when it uses E85 or Gas.


I have #42 injectors that i am going to install and then run with 100% E85. And try to tune in the car. But all help and tips are welcome

So a comparision between the timing on gas and E85 from a vortec E85 would be nice. Anyone know where i should look or ask?


And have found this, Maybe it´s only the VE table that is changed when driving on E85?

For those with tuning software(hptuners 1.7) you see will that there is a table for e85 along with a fuel sensor, the table is primary ve adder. So when it senses e85 it use this ve adder table to the main ve table to get the fuel curve for e85.

[chrisj6]

I know the '03 up trucks and tahoes have an OLFA table for both alchohol and gas, but they are the same values in both tables. Only other thing I know is the engines have larger injectors.

Chris

[EC_Tune]

Check HERE for binaries: Grab an `04 Tahoe L59 Motor Stock file to look over.

You must have the alcohol sensor on your vehicle to utilize the dual OLAFR tables & ethanol in general. If you don't have the sensor, your Stoch value and OLAFR table must change with the known concentration of ethanol in the tank. The VE Table is the same for all fuel concentrations.

EC

[Runn WS7]

Check HERE for binaries: Grab an `04 Tahoe L59 Motor Stock file to look over.

You must have the alcohol sensor on your vehicle to utilize the dual OLAFR tables & ethanol in general. If you don't have the sensor, your Stoch value and OLAFR table must change with the known concentration of ethanol in the tank. The VE Table is the same for all fuel concentrations.

EC

Thanks i´l have a look at it. I´l be running my car at 100% E85 at all time.

[Runn WS7]

OK.. so the flexfuels change the stoich (and what i can see thats the only thing that changes when the sensor senses the E85 is in the gastank), but i should be able to change the VE instead right?

Since the stoich for E85 is 9.765 i think changing the Stoich AFR to 9.765 feels like the right thing to do... Then the PCM can use the stock VE-table.

This is what i plan to do...
Return my VE table to stock (because it is tuned to 50% E85)
Change my Stoich to 9.765
Fill up the tank with 100% E85
Tune in my VE (while checking for knock)

Any ideas?


The O2 sensors would still work. They don't understand AFR, they only understand rich/lean. If you are using regular or E10 the stoich AFR is ~14.7:1 (as you well know) and when the O2s are switching, this is the AFR it is indicating. When you are using E85 (AFR 9.765:1), the O2s will still work, switching between rich/lean. It's just that the point they are switching at is 9.765:1. You have to know what fuel you are burning to properly interpret the information the O2 sensors are providing.
Lambda 1 is always Lambda 1 no matter what you drive your car on, the o2 sensor doesn´t care if the AFR are 14,7 or 9.765... it measures the available o2 in the exhaust gases.

[WS6FirebirdTA00]

i think you have to change your switch points for your o2s as well to run richer. why go through all the trouble to run e85? not putting the idea down just wondering what your reasoning is (skimmed this post fast so i may have missed it)

[Runn WS7]

i think you have to change your switch points for your o2s as well to run richer. why go through all the trouble to run e85? not putting the idea down just wondering what your reasoning is (skimmed this post fast so i may have missed it)

No, I think changing the Stoich AFR should be enough.

For one E85 is alot cheaper here.

[WS6FirebirdTA00]

e85 is cheaper but since stoich is richer, it uses more gas. but i see you arent in the states so that may still not matter to you...

the stock o2s are set to switch around 450 mV and AFAIK that is all they are accurate for switching around and that is 14.7:1 AFR

[EC_Tune]

You can run more timing with E85 as the Octane rating is between 100 & 105 Octane.
Here's a writeup on E85

EC(85)

[Runn WS7]

the stock o2s are set to switch around 450 mV and AFAIK that is all they are accurate for switching around and that is 14.7:1 AFR

The o2´s are not a problem...

The O2 sensors would still work. They don't understand AFR, they only understand rich/lean. If you are using regular or E10 the stoich AFR is ~14.7:1 (as you well know) and when the O2s are switching, this is the AFR it is indicating. When you are using E85 (AFR 9.765:1), the O2s will still work, switching between rich/lean. It's just that the point they are switching at is 9.765:1. You have to know what fuel you are burning to properly interpret the information the O2 sensors are providing.
Lambda 1 is always Lambda 1 no matter what you drive your car on, the o2 sensor doesn´t care if the AFR are 14,7 or 9.765... it measures the available o2 in the exhaust gases.

[S2H]

The o2´s are not a problem...

The O2 sensors would still work. They don't understand AFR, they only understand rich/lean. If you are using regular or E10 the stoich AFR is ~14.7:1 (as you well know) and when the O2s are switching, this is the AFR it is indicating. When you are using E85 (AFR 9.765:1), the O2s will still work, switching between rich/lean. It's just that the point they are switching at is 9.765:1. You have to know what fuel you are burning to properly interpret the information the O2 sensors are providing.
Lambda 1 is always Lambda 1 no matter what you drive your car on, the o2 sensor doesn´t care if the AFR are 14,7 or 9.765... it measures the available o2 in the exhaust gases.

the issue is that the stock o2's are only accurate at 14.63 ish
so if you run E85..and you need to burn to see AFR of 9.765...then you cant use the stock o2's...

when you burn e85 you need to see 9.765AFR at the o2....and thats e85 stoich...period..
if you see 14.63 with e85....then you are doing the same thing as running 22:1 on petrol pump gas....maybe not quite that scale of difference...but lean is lean...

to tune for e85 you either need a sensor that is accurate at e85 stoich..or you need to tune in open loop...and leave it in open loop
you could run a dual wideband setup..adn take the narrowband sides to the stock o2 conector..
run some LC1's and you can change the output of the narrowband side to reflect that e85 stoich is the switchpoint...and it will report the normal petrol gas stioch to the PCM...
that is your best was to run e85 on a non flex fuel vehicle

[bmfcamaro]

cant they look up a vehicle that runs e85 and find the part number for the o2 sensor and cross reference to see if it is the same or not. then if not buy one of those.

[S2H]

cant they look up a vehicle that runs e85 and find the part number for the o2 sensor and cross reference to see if it is the same or not. then if not buy one of those.

I dont know of any from the factory that run full time E85.

either way..a dual wideband simulating the narrow side..would be your best option...

[WS6FirebirdTA00]

The o2´s are not a problem...

The O2 sensors would still work. They don't understand AFR, they only understand rich/lean. If you are using regular or E10 the stoich AFR is ~14.7:1 (as you well know) and when the O2s are switching, this is the AFR it is indicating. When you are using E85 (AFR 9.765:1), the O2s will still work, switching between rich/lean. It's just that the point they are switching at is 9.765:1. You have to know what fuel you are burning to properly interpret the information the O2 sensors are providing.
Lambda 1 is always Lambda 1 no matter what you drive your car on, the o2 sensor doesn´t care if the AFR are 14,7 or 9.765... it measures the available o2 in the exhaust gases.

yes they know rich/lean but they have to know what AFR is rich and what AFR is lean. thats why at WOT they are reading ~900 mV because it is richer. That AFR is most likely out of range of the stock o2s to even be adjusting the switch points. The o2s DO KNOW the AFR to an extent, they just dont put out an AFR reading that you are used to seeing.

and you are right, it measures the o2 in the exhaust, meaning E85 will have less o2 in the exhaust which means it needs a lower switching point or it will try to lean the car out to a 14.7. Try to command a 13.0 for normal driving, it will pull about 10% fuel in the fuel trims and get you right back to 14.7

[WS6FirebirdTA00]

cant they look up a vehicle that runs e85 and find the part number for the o2 sensor and cross reference to see if it is the same or not. then if not buy one of those.

the newer cars have an extra o2 IIRC which can get a reading for E85

[Runn WS7]

the newer cars have an extra o2 IIRC which can get a reading for E85

I´m sorry but you are wrong, Flexfuels use the same o2 that the gas cars...

Again the o2 dont care about what AFR i need they are good at reading Lambda 1 and Lamdba 1 for E85 is 9.765...

I dont know how to explain it better, Do a google on the how the o2´s work and you will se that i am correct.

Fuel AFRst FARst Equivalence Lambda
---- ----- ----- Ratio -----
=======================--====================================

Gasoline stoich 14.7 0.068 1 1
Gasoline Max power rich 12.5 0.08 1.176 0.8503
Gasoline Max power lean 13.23 0.0755 1.111 0.900

=======================--====================================

E85 stoich 9.765 0.10235 1 1
E85 Max power rich 6.975 0.1434 1.40 0.7143
E85 Max power lean 8.4687 0.118 1.153 0.8673

[EC_Tune]

02 sensors on Flex Fuel trucks are the same as standard gasoline trucks.

As stated above the O2 sensors know lambda, not AFR. Stoch is Stoch in this case. You just need the fuel system to know what Stoch is in Air Fuel Ratio vs percent ethanol/methanol/Everclear.

The other point to remember is that ethanol (E85) is an oxygen bearing fuel (contains it's own oxygen: C2H5OH for Ethanol, CH3OH for Methanol) thus the "richer" stoch point. The O2 sensor "sees" this additonal oxygen and adjusts accordingly.