Tuning/tweaking with 100% gasoline vs gas/ethanol blend
10-26-2017, 08:55 PM
#1
Tuning/tweaking with 100% gasoline vs gas/ethanol blend
I’ve ventured down the DIY tuning road and it’s opened up quite a bit of new things for me. One thing that came up is the fuels we use today. I assume GM designed the tunes in these cars with 100% gasoline in mind. Now, it seems that 99% of us fill up with what is at the pump today i.e. enthanol blended fuel.
Can the ECM compensate for the two types of fuel? I’m seriously considering running 100 % gasoline in the 91-95 octane range.
What are your thoughts guys?
Can the ECM compensate for the two types of fuel? I’m seriously considering running 100 % gasoline in the 91-95 octane range.
What are your thoughts guys?
10-26-2017, 09:19 PM
#2
Re: Tuning/tweaking with 100% gasoline vs gas/ethanol blend
Feeling drunk with power, are ya now laddy? 
From what I understand, the ECM can adjust for the blend and you'll see it in the BLM's (the fuel trim indicator value will drift significantly away from the ideal 128 value. What it won't adjust for is open loop and power enrichment (ignores the O2 sensor in those modes).
To correct for it, you can change the stoichometric constant. I've heard/seen of constants being run from 14.0 to 14.5 (for pure gasoline it's 14.7). This will bring the BLMs back in line and correct any deviations to the PE and OL AFR's. That's if you're not planning to change anything else in the calibration.
However, AFIK, if you're going to start re-programming the PE and OL (using a WB O2) along with VE, it's probably not necessary to adjust the stoich constant since you're going to be re-programming based on actual AFR's being measured. In other words, simply leave the stoich constant at 14.7:1 and just rework the fueling tables based on measured WB O2 AFR's.
From what I understand, the ECM can adjust for the blend and you'll see it in the BLM's (the fuel trim indicator value will drift significantly away from the ideal 128 value. What it won't adjust for is open loop and power enrichment (ignores the O2 sensor in those modes).
To correct for it, you can change the stoichometric constant. I've heard/seen of constants being run from 14.0 to 14.5 (for pure gasoline it's 14.7). This will bring the BLMs back in line and correct any deviations to the PE and OL AFR's. That's if you're not planning to change anything else in the calibration.
However, AFIK, if you're going to start re-programming the PE and OL (using a WB O2) along with VE, it's probably not necessary to adjust the stoich constant since you're going to be re-programming based on actual AFR's being measured. In other words, simply leave the stoich constant at 14.7:1 and just rework the fueling tables based on measured WB O2 AFR's.
10-27-2017, 10:04 AM
#5
Re: Tuning/tweaking with 100% gasoline vs gas/ethanol blend
yes, I found a place within an hours drive of me that has non ethanol gasoline 95 octane. They want $80 for a 5 gallon container of it. Im curious to see if the engine runs better on it.
My garden tractor is a 1977 model year with a Kohler engine which HATES this new fuel so I am already leaning towards buying non ethanol fuel for that. I just wanted to know if it was worth it to use it in my car as well. I only put about 600 miles a year on the car. I hate fuel sitting in the tank for a month at a time
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11-05-2017, 03:31 PM
#8
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Re: Tuning/tweaking with 100% gasoline vs gas/ethanol blend
Because the o2 reads the oxygen it runs stoich with either fuel. I found this was a great read.
https://www.hptuners.com/forum/showt...our-LS1-on-E85
https://www.hptuners.com/forum/showt...our-LS1-on-E85
11-05-2017, 07:11 PM
#9
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Re: Tuning/tweaking with 100% gasoline vs gas/ethanol blend
**** we pay 9.99 for C10....no not worth it for that much if you drive if a lot, if you put 50 miles a hear yes, cause it'll not turn to sand in your engine.
11-09-2017, 05:39 PM
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Re: Tuning/tweaking with 100% gasoline vs gas/ethanol blend
Your fueling adaptives will make up for the differences in E-0 & E-10 fuel. The differences in oxygen content is only a few percent. If you would like to optimize the stoic target for E-10, set the value to 13.7:1.
12-05-2017, 06:24 PM
#11
Supreme Member
Re: Tuning/tweaking with 100% gasoline vs gas/ethanol blend
yes, I found a place within an hours drive of me that has non ethanol gasoline 95 octane. They want $80 for a 5 gallon container of it. Im curious to see if the engine runs better on it.
My garden tractor is a 1977 model year with a Kohler engine which HATES this new fuel so I am already leaning towards buying non ethanol fuel for that. I just wanted to know if it was worth it to use it in my car as well. I only put about 600 miles a year on the car. I hate fuel sitting in the tank for a month at a time
My garden tractor is a 1977 model year with a Kohler engine which HATES this new fuel so I am already leaning towards buying non ethanol fuel for that. I just wanted to know if it was worth it to use it in my car as well. I only put about 600 miles a year on the car. I hate fuel sitting in the tank for a month at a time
Purchase premium (93 E10 here) at a station, 5 gallon jug. I use a VP racing jug.
Take home, dump in 2 liters of water
Shake well for 10-20 seconds
Let sit for several hours (best overnight).
In the morning, the water and ethanol will mix, and water being more dense than gas will sink to the bottom. Then, just drain the water\ethanol mixture out of the bottom of your jug, and you are left with 4.5 gallons of gas. I drain the water\ethanol out by just turning the jug over, and opening up a valve I installed from home depot that fit perfectly in the VP racing jug lid.
BTW you need 93 since ethanol is an octane booster. When you remove the octane in 93, itll drop down a few points. If you start out with regular 87 and remove the ethanol, that's probably too low of an octane to run in a vehicle.
12-05-2017, 08:24 PM
#12
Re: Tuning/tweaking with 100% gasoline vs gas/ethanol blend
That seems like an awful lot of trouble (not to mention dealing with the smelly vapors) when retuning for the stoich constant is so simple...
12-06-2017, 10:45 AM
#13
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Re: Tuning/tweaking with 100% gasoline vs gas/ethanol blend
Feeling drunk with power, are ya now laddy?
From what I understand, the ECM can adjust for the blend and you'll see it in the BLM's (the fuel trim indicator value will drift significantly away from the ideal 128 value. What it won't adjust for is open loop and power enrichment (ignores the O2 sensor in those modes).
To correct for it, you can change the stoichometric constant. I've heard/seen of constants being run from 14.0 to 14.5 (for pure gasoline it's 14.7). This will bring the BLMs back in line and correct any deviations to the PE and OL AFR's. That's if you're not planning to change anything else in the calibration.
However, AFIK, if you're going to start re-programming the PE and OL (using a WB O2) along with VE, it's probably not necessary to adjust the stoich constant since you're going to be re-programming based on actual AFR's being measured. In other words, simply leave the stoich constant at 14.7:1 and just rework the fueling tables based on measured WB O2 AFR's.
From what I understand, the ECM can adjust for the blend and you'll see it in the BLM's (the fuel trim indicator value will drift significantly away from the ideal 128 value. What it won't adjust for is open loop and power enrichment (ignores the O2 sensor in those modes).
To correct for it, you can change the stoichometric constant. I've heard/seen of constants being run from 14.0 to 14.5 (for pure gasoline it's 14.7). This will bring the BLMs back in line and correct any deviations to the PE and OL AFR's. That's if you're not planning to change anything else in the calibration.
However, AFIK, if you're going to start re-programming the PE and OL (using a WB O2) along with VE, it's probably not necessary to adjust the stoich constant since you're going to be re-programming based on actual AFR's being measured. In other words, simply leave the stoich constant at 14.7:1 and just rework the fueling tables based on measured WB O2 AFR's.
That is right on!!! Fortunately, I can get 91 octane without ethanol in this neck of the woods. I was getting 94 octane before but they were putting ethanol in it. AFR gauge was showing lean at WOT... Not good. Ethanol blend as less energy per volume.
12-07-2017, 08:35 PM
#14
Supreme Member
12-07-2017, 09:05 PM
#16
Supreme Member
Re: Tuning/tweaking with 100% gasoline vs gas/ethanol blend
He mentioned $16 ethanol free gas and leaning towards buying fuel for the tractor. I said that he can make it by simply buying $2.50 gallon premium, some water, and time and effort.
Just grab a 5 gallon jug each time you pass by the gas station and fill it up on the way home. I wouldnt advise filling up a 30 gallon tank in the truck and taking it home and taking out the ethanol lol, plus i think its illegal anyway to carry a big amount unless youre a tanker anyway.
Just grab a 5 gallon jug each time you pass by the gas station and fill it up on the way home. I wouldnt advise filling up a 30 gallon tank in the truck and taking it home and taking out the ethanol lol, plus i think its illegal anyway to carry a big amount unless youre a tanker anyway.