Flex Fuel questions

[asshanson]

I know there was a group buy awhile back on those ethanol content LCDs but they seemed pretty expensive so I decided to wait. Does anyone know who organized that, or how they came up with the specs to send to the manufacturer? I know some of the sensors have three wires: power, ground, and signal, so all you need is a lookup table or formula to map voltage or hz to ethanol percentage.

Are the ford and GM sensors different? Were the LCDs made to work with a certain brand or part number, who actually makes the sensors? Also, where did people find the sensors, in a junk yard? Online they seem to sell for $600+ new which is ridiculous.

I know I could look up some of the information myself, but if someone else has already done the research I figured it would be worth sharing with the group.

Thanks,
Andrew

[asshanson]

Found some good info at http://www.megamanual.com/flexfuel.htm

Sensor frequency output, 50-150hz linear (0-100% ethanol):

The frequency of the signal indicates the ethanol percentage. The output frequency is linear with respect to the percentage of ethanol content in the fuel. The PCM provides an internal pull-up to five volts on the signal circuit, and the fuel sensor pulls the 5 volts to ground in pulses. The normal range of operating frequency is between 50 and 150 Hertz:
o 50 Hertz indicates 0% ethanol, and
o 150 Hertz indicates 100% ethanol.


Fuel temp doesn't matter to me, but may be useful to some:

The pulse width indicates the fuel temperature. The normal pulse width is between 1 and 5 milliseconds:
o 1 millisecond indicates -40°C (-40°F), and
o 5 milliseconds indicates 125°C (257°F).

The article also specifies part numbers and where to get the sensors for cheap, and from other articles they all seem to have the same basic Hz output:

Initial testing has been done with the GM fuel composition sensor part number #12570260, which is their latest version of the flexible fuel sensor. The list price is somewhere around $500 (!), a few online parts places has these for $360 or so. However, if you do a search on eBay for "flex fuel", there is a sensor from seller Medimars,who is offering brand new GM sensors (number #12568450, for a 2001 S-15 truck) for $50.00 plus shipping. It operates the same as the other part number sensor. This latter number has been discontinued by GM, replaced by the former number for most vehicles.

For those of you who have this working, how did you hook up the sensor, it doesn't look easy to fit into a fuel feed line unless they make an AN adapter for one of these to tap into a line like a pressure gauge would.

[Shane@DBPerformance]

Let us know if you find any cheap sensors. That Megasquirt info is quite old and I couldn't find any of those Medimar sensors even a couple years ago.

[merkzu]

The hardest part is getting a sensor.. the LCDs only work with the GM (Seimens) sensor afaik.. unless the ford ones put out the exact same signal

Zeitronix has a pretty sweet new product out to work with it too - http://forums.evolutionm.net/showthread.php?t=379153

[SnoEclipse]

excuse my ignorance, but for a lightly modified car driven on the street, why would I need or want to know the ethanol content and temperature of my fuel?

[Jakey]

FYI Andrew....

If you're in the Ames area, there is a new blender pump in Gilbert. You can get E10, E20, E30, E40, and E85. So far, my Grand Prix is loving the E40.

[asshanson]

For lightly modified, it probably wouldn't matter. But if the mix changes from 85% down to 70% I want to know, I don't want to have to hook up my laptop every fillup and see if my fuel trims changed.

You might want to change the global fuel compensation a few percent, and I turned down the boost a couple PSI with the lower octane.

Anyway I think I've come up with a good idea on how to make these cheap if I can find a sensor. More details to come once I work out a few remaining issues.

[asshanson]

FYI Andrew....

If you're in the Ames area, there is a new blender pump in Gilbert. You can get E10, E20, E30, E40, and E85. So far, my Grand Prix is loving the E40.

Sweet, I'll have to check it out, I'll be up there this weekend probably. What station is it at?

[Jakey]

Sweet, I'll have to check it out, I'll be up there this weekend probably. What station is it at?
The Heart of Iowa Cooperative station across Highway 69 from Casey's.

[asshanson]

Does it actually let you put in 85 in the winter or is it restricted to 70 like everything else?

If only I had the sensor setup done I could find out myself...