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Just a thought...
Posted 02 April 2007 - 12:50 AM
Posted 02 April 2007 - 07:44 AM
Posted 02 April 2007 - 08:19 AM
Still, I could be wrong.. I, myself, just do mileage counts after filling up. Can't get much more accurate then that.
Posted 04 April 2007 - 01:06 PM
...I, myself, just do mileage counts after filling up. Can't get much more accurate then that.
Well... Me Too!
I Just Overfill the Fuel tank to its Limit, put the Miles Counter on the Dash on "0" and Do a Trip, at its End, I Refill the Tank and count how many Gallons where Used, then Calculatin´ how Many Miles I´ve done whith ´em, and That´s my Miles per Gallon Measurement.
Not very Accurate, but Since City / Road \ Highway Mileage and Drivin´ conditions Vary; it Gives me a Good Average.
For Example, my EA82 Weberized White Wagon, does around 40 Miles per Gallon in Highways, but just Around 30 in Cities...
Maybe this Idea could Help you...
Posted 04 April 2007 - 01:09 PM
you just have to use some electronics to do this calculating for you and display the results
flow meters are expensive though, just thought I might warn you.
Posted 04 April 2007 - 06:23 PM
Posted 04 April 2007 - 06:26 PM
I don't think that I'd be able to actually monitor how much fuel is going through the injector. I'd only get an idea of how much should be going through after some calculations.
Since the pressure is regulated, it shouldn't be a variable.
Since the manifold vacuum isn't what draws the fuel in, it should make a big difference.
Theoretically, if you measuring the width of the pulse going to the injector should tell exactly how much fuel went in. You just need a computer - analog or digital - to convert to a usable reading.
Longer the pulse = more fuel.
Pretty simple analog circuit to average out the pulses for a flow rate meter.
For MPG meter, it would be better to go digital = computer.
Posted 04 April 2007 - 11:09 PM
SPFI uses a constant fuel pressure, but multiport uses a varying pressure to keep a constant over intake pressure.
If you want and accurate meter, use a vacuum gauge. Less vacuum means more air in the intake, more air needs more fuel-
Other than that, just keep your foot out of it.
Posted 11 April 2007 - 05:52 AM
Posted 11 April 2007 - 01:13 PM
I have thought of using the signal to the injector, as DaveT suggests. A simple RC circuit should convert this to an analog signal proportional to flow. There is also an input to the ECU from the VSS (vehicle speed sensor I presume), but I have no idea what this signal looks like, or how it could be converted to a usable signal for either a digital or analog computer.
Anyone out there with an oscilloscope who wants to have a look for us?
A digital computer would be the best, and perhaps easiest means of calculating the MPG, but I wouldn't mind playing around with an analog one, if I had some idea what the VSS signal output looked like.
Posted 11 April 2007 - 01:23 PM
Seeing that air fuel ratios are always constant, if you read the voltage of the Air flow meter, that would give you an indication of how much air and thus fuel you are using.
Actually they aren't.
Posted 22 April 2007 - 01:14 AM
Actually they aren't.
I know that they vary a bit, but fuel input must be proportional to air input otherwise it would run lean or rich and not run very well at all.
If i am wrong, please explain how cos i love learning about these sorts a things.
Posted 22 April 2007 - 10:38 AM
Posted 23 April 2007 - 10:21 AM
Better to measure the actual fuel flow. It is probably easier than measuring the air flow signal, and trying to calibrate that back to fuel. At least we know what the fuel injector will flow when open, I don't believe we know how much air comes through the system.
The VSS signal would be about what I would expect. There is a simple tach chip that would turn it into an analog signal, very cheap, and been around for years.
Posted 25 April 2007 - 03:38 PM
You get 40mpg? Is Honduras mostly level ?
I have never seen that kind of mileage out of 7 subaru's I've owned, But I cannot go ANYWHERE that's not up/down hill.
Posted 25 April 2007 - 04:17 PM
I can get 38 MPG with my Loyale 4WD. It is hard work, and slow, but it can be done. I can see a carefully-driven, well-maintained 2wd with Weber tuned to the nuts being able to beat that. I remember Loyale 2.7 has also recommended disconnecting the secondary throttle linkage, to get better fuel economy. With that kind of an attitude, almost anything is possible!
Posted 25 April 2007 - 04:23 PM
You get 40mpg?
I get 40 mpg consistently between Carson City, Nv and Markleeville, Ca. Thats also the only drive that I do get that kind of mileage. About 80 miles round trip. I'm not sure what the elevation change is, but it does take me into the Sierra Nevadas.
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