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Fueling the E85 community
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abqautotech
Joined: 12 Jan 2006
Posts: 11
Location: 1942 Broadway ne
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 Posted: Thu Jan 26, 2006 8:17 pm Post subject: |
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| Corn Squeezins wrote: | Yes I would think u could technically hook up a sensor such as this...
but... what u would need is a control unit that could intervene with the
fuel system or a special pcm to actually utilize the data in any productive way other than a high tech alcohol sensor for manual output of a freq.
denoting alcohol percentage. In other words, what good is it on our cars
if we have no way of using it for the computer? I think u would need
a custom pcm or something as this would be hard to just "add" to a normal car pcm in any realistic way. Also it would require cobbling it into
a line somewhere and installing safe connection with different line materials, steel, nylon, rubber hoses, etc. Not exactly going to gain us much in the real world is what I see for this sensor use on other cars not designed for it. Maybe a special flex tek unit could be used but other than
that I don't see any point, do you? |
As long as the vehicle is fuel injected a special computer is not needed to just run E85. To take full advantage of E85's qualities some modification is needed. We have been running E85 in both are personal cars, one 94 caprice the other 88 Honda without modification. Fuel mileage has suffered but once we reflash the computers we will remedy this. Emmissions test are showing the High speed Carbon monoxide to be cut in half also.
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Albuquerque Auto Tech
1942 Broadway ne
ABQ NM 87102
505-247-0980 |
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Corn Squeezins
Joined: 14 Dec 2005
Posts: 42
Location: Madison, WI
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| Posted: Sat Jan 28, 2006 3:57 pm Post subject: |
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abqautotech, no one said you need a special pcm. The question asked was if it was a good suggestion to use a flex fuel sensor in some way with
stock pcms in order to better run E85. No, technically most vehicles will run E85 in some partial percentage, it will run like dog doo when cold starting with out some modifications to a stock system, such as raised fuel pressure, bigger injectors, flex tech type add on pcms, etc. on 100 percent fill of E85. Otherwise I know for a fact here in WI that even at 55-60 deg. F. that it will run very rough & stall until enough heat is built up to overcome the latent heat absorbtion in the engine/cyl, to support this quite lean mixture. Can this be alleviated with special pcm programming, chips on older ecms, YES! But stone stock systems on most cars will start hard, run like crap, etc. until warm & then will start to smooth out when warmed up. If that isn't a problem for someone to have a finicky car when starting then so be it, but you are correct in saying that yes ... "To take full advantage of E85's qualities some modification is needed". Other than test mules & so called beaters no ones spouse will be too impressed with how their non-E85 vehicle would run on a full tank of pure E85. So yes some mods are needed to use higher than about 50-60 % blends in STONE STOCK vehicles! |
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B.A.Bowling
Joined: 15 Feb 2006
Posts: 6
Location: Baltimore, MD
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| Posted: Thu Feb 16, 2006 8:47 pm Post subject: |
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| abqautotech wrote: |
As long as the vehicle is fuel injected a special computer is not needed to just run E85. To take full advantage of E85's qualities some modification is needed. We have been running E85 in both are personal cars, one 94 caprice the other 88 Honda without modification. Fuel mileage has suffered but once we reflash the computers we will remedy this. Emmissions test are showing the High speed Carbon monoxide to be cut in half also. |
Many OEM ECUs have a closed-loop authority range that may allow enough adjustment to compensate for a mix of ethanol to gasoline, but there will be a point where the range is exceeded. At this point the ECU will hit an upper limit to the amount of fuel enrichment it will provide over the base calculated amount, so there is a chance of running a bit lean wiith mixtures approaching pure ethanol.
Issues remain with open-loop tables, like cranking enrichments and the like, without direct user modifications to compensate.
Finally, the question on the elimination of flex-fuel sensors on the latest OEM vehicles came up on this thread. This is known as a "virtual O2 sensor" mode. Its pretty simple in operation, here is a quick explaination:
Most ECUs use a mixture adjustment method to tweak it in for changes in environment. Known to many as block learn (BLM), what this does is take the base fuel tables and apply an offset term to large sections of the table in order to maintain a balance in the O2 dithering. In other words, the O2 sensor is used as a feedback to determine the stoich point, and in a perfect car/environment this point corresponds to the calculated base fuel. But due to various environmental conditions, aging, etc , the switch point will drift, and an offset value will be computed which brings the switch point to a nominal point.
Now, if after running, the entire block(s) has rougly the same offset value across the load/rpm range, then it can be inferred that a "global" change in fueling has occurred. A change in the hydrocarbon content can cause this to occur. So, a global "bias" can now be computed and applied which shifts all of the fuel tables to compensate (including startup enrichments, etc).
- Bruce |
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aero
Joined: 23 Feb 2006
Posts: 3
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| Posted: Thu Feb 23, 2006 1:07 am Post subject: |
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| chenely63 wrote: | the flex fuel sensor used on the S 10, can it be read out with a DVM with a frequency range?
Leo |
http://www.megasquirt.info/flexfuel.htm This link was posted in another thread by B. A Bowling. There is information about the output signal of this sensor there. |
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