Anyone running megasquirt with Ethanol?
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Danny90033
- Club4AG Regular
- Posts: 32
- Joined: Fri Mar 29, 2013 1:28 am
Anyone running megasquirt with Ethanol?
Looking to see if anyone can give me advice on this particular issue
Re: Anyone running megasquirt with Ethanol?
Find a 2006 GMC or Chevrolet pickup for a Z code 5.3L engine, which is the L59 flex fuel engine, and use the following table :
Stoichiometric AFR vs. % Alcohol In Fuel
% Alcohol / AFR
0.0 14.7
6.25 14.3
12.50 14.0
18.75 13.6
25.00 13.3
31.25 12.9
37.50 12.6
43.75 12.2
50.00 11.8
56.25 11.5
62.50 11.1
68.75 10.8
75.00 10.4
81.25 10.1
87.50 9.7
93.75 9.4
100.0 9.0
The signal generated from the Flex-Fuel sensor (Siemens) tells the PCM two things. Fuel Temperature and Alcohol Content % .
Signal generated is a square-wave signal. The signal is variable by frequency and by pulse width.
Frequency is indicated ethanol percentage, and pulse width indicates fuel temperature.
Normal frequency range is 50-150 hertz …50 hertz = 0% ethanol, 150hertz=100% ethanol
Normal pulse width range is 1 – 5 milliseconds…. 1 = -40F, 5=257F
The sensor has a self diagnostic system, with output frequency of 170 = fuel is contaminated …or contains methanol, or an internal electrical fault has occurred.
You can map this into a Megasquirt and then directly read and adjust your fueling depending on actual ethanol content.
HTH
Stoichiometric AFR vs. % Alcohol In Fuel
% Alcohol / AFR
0.0 14.7
6.25 14.3
12.50 14.0
18.75 13.6
25.00 13.3
31.25 12.9
37.50 12.6
43.75 12.2
50.00 11.8
56.25 11.5
62.50 11.1
68.75 10.8
75.00 10.4
81.25 10.1
87.50 9.7
93.75 9.4
100.0 9.0
The signal generated from the Flex-Fuel sensor (Siemens) tells the PCM two things. Fuel Temperature and Alcohol Content % .
Signal generated is a square-wave signal. The signal is variable by frequency and by pulse width.
Frequency is indicated ethanol percentage, and pulse width indicates fuel temperature.
Normal frequency range is 50-150 hertz …50 hertz = 0% ethanol, 150hertz=100% ethanol
Normal pulse width range is 1 – 5 milliseconds…. 1 = -40F, 5=257F
The sensor has a self diagnostic system, with output frequency of 170 = fuel is contaminated …or contains methanol, or an internal electrical fault has occurred.
You can map this into a Megasquirt and then directly read and adjust your fueling depending on actual ethanol content.
HTH
"When the going gets, wierd, the Wierd turn Pro" -- Hunter S. Thompson
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Danny90033
- Club4AG Regular
- Posts: 32
- Joined: Fri Mar 29, 2013 1:28 am
Re: Anyone running megasquirt with Ethanol?
Thank you, I heard a lot of rumors that the whole fuel system has to be changed on older cars to handle the corrosive nature of ethanol. Do you know if the ae86 4age fuel system has to be upgraded besides the fuel pump and injectors to allow more flow?
Re: Anyone running megasquirt with Ethanol?
Ethanol (E85), like methanol fuels, is both dipolar and corrosive.
By diplolar I mean the fuel itself can carry a static charge and therefore can electrically "etch" components, especially if they present an opposite electrical field due to wiring.
So certain things have to be considered if you want to run E85.
First and foremost is that nitrile o-rings, as well as neoprene, will not tolerate this stuff.
Use only Viton or Flourosilicone o-rings in the system. for injector and any other o-ring seals encountered.
Viton-B is the preferred o-ring as it both has ethanol tolerance with little swelling and low temperature performance.
Now for injectors. Early injectors (Bosch, ND, Diesel Kikki, Siemens, and Rochester Products) all use internal o-rings that are not E85 compatible.
So use them at your risk, as they will eventually leak. Also, the steels are not compatible with E85 and will corrode and the injector guides will wear, changing performance over time.
Starting with the reduced diameter EV6 type injectors, most of these are compatible as they were designed by Bosch, Siemens, ND and RP for alcohol-laced fuels.
So stainless steels are used.
But most of these are high Impedance injectors of 12 to 16 Ohms in measured resistance. If those can be used, find sets that will flow the approximately 40% MORE that E85 will require.
If you are using "side-feed" or "bottom-feed" injectors, you kind of have a problem in that only a very few of these will have materials that tolerate E85.
Even with correct injectors, you need to make sure the field polarity is right for your system (remember the dipolar comments?). Bosch has a "+" and sometimes a "-" as well on their injectors.
Plus (+) terminal is always wired to sourced battery voltage and the other terminal goes to control or ground depending on whether you are sourcing voltage (PNP transistor) or sinking voltage through the injector (NPN transistor).
Most circuits use a variation of the NPN, whether bipolar or MOSFET type transistors, as these have better diagnostics.
Fuel pumps must come from vehicles that are flex-fuel compatible. GM pickups, Ford products with E85 labels are the ones to specify to the parts monkeys to get the correct pumps. Expect to pay a little more, as they cost more to manufacture.
Same now with fuel pressure regulators. Those aluminum AEM units look great and get eaten up by E85 as they use rubber diaphragms. The E85 ones generally use either reinforced Viton diaphragms of thin stainless steel ones.
Now we get to lines. Rubber is a no-no. Use either SS lines or Teflon lined steel or flexible hose. Use steel Aeroquip AN fittings as these work. You are trying to "ground" the lines to dissipate the static charge buildup.
A good place to do this is at the fuel filter. Use one from an E85 application so the fuel doesn't dissolve the glues in the filter screening. Tie a ground strap from the metal case to the chassis to positively ground the system.
That is basically the route to take to go to an E85 tolerant system.
By diplolar I mean the fuel itself can carry a static charge and therefore can electrically "etch" components, especially if they present an opposite electrical field due to wiring.
So certain things have to be considered if you want to run E85.
First and foremost is that nitrile o-rings, as well as neoprene, will not tolerate this stuff.
Use only Viton or Flourosilicone o-rings in the system. for injector and any other o-ring seals encountered.
Viton-B is the preferred o-ring as it both has ethanol tolerance with little swelling and low temperature performance.
Now for injectors. Early injectors (Bosch, ND, Diesel Kikki, Siemens, and Rochester Products) all use internal o-rings that are not E85 compatible.
So use them at your risk, as they will eventually leak. Also, the steels are not compatible with E85 and will corrode and the injector guides will wear, changing performance over time.
Starting with the reduced diameter EV6 type injectors, most of these are compatible as they were designed by Bosch, Siemens, ND and RP for alcohol-laced fuels.
So stainless steels are used.
But most of these are high Impedance injectors of 12 to 16 Ohms in measured resistance. If those can be used, find sets that will flow the approximately 40% MORE that E85 will require.
If you are using "side-feed" or "bottom-feed" injectors, you kind of have a problem in that only a very few of these will have materials that tolerate E85.
Even with correct injectors, you need to make sure the field polarity is right for your system (remember the dipolar comments?). Bosch has a "+" and sometimes a "-" as well on their injectors.
Plus (+) terminal is always wired to sourced battery voltage and the other terminal goes to control or ground depending on whether you are sourcing voltage (PNP transistor) or sinking voltage through the injector (NPN transistor).
Most circuits use a variation of the NPN, whether bipolar or MOSFET type transistors, as these have better diagnostics.
Fuel pumps must come from vehicles that are flex-fuel compatible. GM pickups, Ford products with E85 labels are the ones to specify to the parts monkeys to get the correct pumps. Expect to pay a little more, as they cost more to manufacture.
Same now with fuel pressure regulators. Those aluminum AEM units look great and get eaten up by E85 as they use rubber diaphragms. The E85 ones generally use either reinforced Viton diaphragms of thin stainless steel ones.
Now we get to lines. Rubber is a no-no. Use either SS lines or Teflon lined steel or flexible hose. Use steel Aeroquip AN fittings as these work. You are trying to "ground" the lines to dissipate the static charge buildup.
A good place to do this is at the fuel filter. Use one from an E85 application so the fuel doesn't dissolve the glues in the filter screening. Tie a ground strap from the metal case to the chassis to positively ground the system.
That is basically the route to take to go to an E85 tolerant system.
"When the going gets, wierd, the Wierd turn Pro" -- Hunter S. Thompson
Re: Anyone running megasquirt with Ethanol?
I run e85 on my turbo ae92 ,fuel setup consist of 2 walbro 255lph one intank and one inline.The feed line is -8 braided line ,return line used to be the feed line.I have custom fuel rail and 1000 cc injectors.I recommend using regular at least one a week if is a daily driver ,if is weekend worrier drain all e85 after use and run some gasoline through.