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A simple way to convert to E85 and have the option to use gasoline

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This is from the Robert Warren Topica forum (Charles 803 Still):

 

RE: Computer Chip?    Bruce Bierman 

  May 23, 2006 07:22 PDT 

 

I did use a 10k pot during testing and tuning and this would be a great

way to tune your individual vehicle. Another thing I did was add a

toggle switch across the resistor to bypass the resistor if E85 is not

available and gasoline must be used. The pot would do the same thing

when turned to 0 ohms. This is much more convenient than changing a

chip.

 

 

 

Bruce

 

 

OER-@aol.com wrote:

 

 

 

In a message dated 5/22/2006 9:17:03 PM Central Daylight Time,

rp-@gvtc.com

writes:

 

 

I have a 93 eclipse with a 1.8 and have been running E85 for over

10,000

miles. With no engine modifications, the O2 sensor would only produce

about 100 mv, which is too lean and caused the check engine light to

come on. To richen the mixture, I added a 5k resistor in series with

the intake air temperature thermistor. The ecm interprets the intake

air

as colder than actual and richens the mixture accordingly. The fuel

mixture is now within limits and the car runs better than ever. NO

check

engine light. I also advanced timing about 5 degrees. The mileage did

 

decrease from 37.5 mpg to 35.4 mpg.

 

I'm new to this discussion list and received plans for the 803 still

today.

 

Bruce

 

 

 

Bruce has given us the ultimate fix: put a variable resistor instead

of the

5k, and you can tune it on the fly from the dash. Look at something

like a

1k - 10k potentiometer (10-turn for precision), and off we go. No,

Gilles, I

don't think that one can be patented. One word of caution, don't do

this in

a state where your vehicle is subject to EPA inspection, or there could

be

unpleasant repercussions. The modification has not been approved by

EPA or

CARB. Get enough voters to turn over the congress and we can change

all

that...george

 

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Interesting stuff Jeremy  .. Now for those of us that dont have the technical skills we'll need to go do our research

 

 

 

"The present popular usage of the term potentiometer (or 'pot' for short) describes an electronic component which has a user-adjustable resistance"

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This would work good for someone who can't use a Flextek or flextune converter.  Or if you didn't want to spend the money for one of those converters.

 

Turning the resister to 0 ohms would let you use gasoline and setting it somewhere around 5K ohms will let you run E85.

 

Use a switch wired around the pot will bypass the 5K of resistance when the switch is closed.  Then you wouldn't have to try to re-adjust the pot back to where it was when switching back and forth from gasoline to E85.

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The part that intriques me is the colder air runs leaner statement  .... I was not aware of that .. I always thought it was Volume of Air in ratio to volume of fuel .

 

which leads me to the question ..so what happens when it's hot outside ?  Wouldnt the resistor set itself to zero and you'd still end up running lean ?

 

 

 

 

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A thermistor temp sensor increases it's resistance when it gets colder.  Colder air is more dense so it has more air when it is cold.  If you make the vehicles computer think that it has cold air by adding resistance it will make the fuel/air more rich by compensating by adding more fuel or by less air. 

 

The temp sensor resistance is linear.  Increases with lower temps decreases with high temps.  The pot would make it think it was cold out side (offset the temperature).  The temp sensor will still go up and down in resistance as it would of normally.(but with the pot's resistance added)  The vehicle would think it was getting more air than it actually is.  So it would adjust it self to a richer fuel/air mixture.

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A thermistor temp sensor increases it's resistance when it gets colder.  Colder air is more dense so it has more air when it is cold.  If you make the vehicles computer think that it has cold air by adding resistance it will make the fuel/air more rich by compensating by adding more fuel or by less air. 

 

The temp sensor resistance is linear.  Increases with lower temps decreases with high temps.  The pot would make it think it was cold out side (offset the temperature).  The temp sensor will still go up and down in resistance as it would of normally.(but with the pot's resistance added)  The vehicle would think it was getting more air than it actually is.  So it would adjust it self to a richer fuel/air mixture.

 

 

Thanks Jeremy I get it now.. 

 

very interesting..maybe I'll test in on my wifes car  :D

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Sorry guys.  While this may work on some vehicles, it won't work on all vehicles.  For example.  Beginning in 2004, Ford narrowed significantly the fuel adjustment range for the F150s.  This was quickly seen by a few pickup truck owners who installed higher flowing air intakes in their 2004s.  The added air quickly resulted in CELs P0171 and P0172 Engine Banks Too Lean.  So.  If this method were attempted with the 2004 - 2006 Ford F150s the result would not be comparable to those experienced below. 

 

It is; however, important to point out that testing of the Flextek has produced solid results so far since the Flextek does not attempt to adjust the PCM.  It instead lengthens fuel injector pulse widths.  Still,  I have my concerns about this as my reading has shown that this is done on a % basis and does not appear to be adjustable.  I am currently running a 70 / 30 blend in my truck with no adverse results.  The calculated resulting octane for this mix is 96.  The adjustments are being handled predictably with no apparent fuel economy loss at this time.  I will stay with this blend for another 1000 miles before move to straight E85 and continuing my test.  The flextek, while installed, is currently set to Gas.   

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tschaid,

 

That's what I did when I installed my Flextek converter.  Installed it but ran regular gasoline to see if there was any changes, then stepped up the percentages.  I also did this before I installed it to compare before and after.  I also noticed running 50/50 gas/alcohol my car liked being on the A setting rather than G.

 

As far as the adding the resistor to the temp sensor,  the only time you would have problems would be if it was really cold out.  I would have to do a little research on the range of thermistors they use to see how much of an offset in temp this would make it see.  If it made the range too far out of wack the vehicles computer might think it wasn't working and set a code.

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OK  I found this http://frontiernet.net/~dbipes/tempsens.htm while looking for info on air intake sensors.

 

This guy did the same thing only using the coolent temp sensor.  He did it for gasoline fuel boost not to convert to E85.  I don't know if it would work the same as the air intake.  I would imagine you would get a code(coolent temp low)  if this was left in for a length of time.  So might have better luck with the intake air.  Still looking into this!

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