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Old 05-14-2008, 08:35 AM   #41
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"It occurred to me that you could wire up a LED indicator light (for example "green" for "go") in parallel with the fuel injector (so that the LED is run by the same signals that trigger the FE to use fuel)"

I don't think this will work, because the injector is controlled by pulse width, not increased/decreased voltage. In other words, I think you will just see a steady glow. The LED is not going to report pulse width.
I don't see why not.

LEDs have very fast (a small fraction of a second) on/off times. So the effect of a longer pulse width should be longer "on time" for the LED. And since our minds likely can't can't keep up with that "flicker rate", our minds should blur the on/off flicker together, and just perceive a longer on time as a brighter light, and a shorter on time (which corresponds to shorter FI pulses) as a dimmer light.

At least, that's the theory. As I said, I haven't yet spent the time to do this with my own car. But it is on my list of projects to do at some point...
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Old 05-14-2008, 08:53 AM   #42
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I looked through Ebscohost for the articles listed in there. I've found only this one:
Build a duty-cycle monitor. By: Campisi, Skip, Popular Electronics, 1042170X, May97, Vol. 14, Issue 5 (in Ebsco's "MasterFILE Premier" database)

It's got the full text, parts list, and photos of the finished product but the circuit diagrams are missing. I think there's enough info in this thread that it's no loss anyway.
Our library has that, and I've hit that problem before, half the stuff in there is fraggin' useless without the diagrams, results tables, graphs, or in this case circuit diagrams the text is referring to.
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Old 05-14-2008, 09:38 AM   #43
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I don't see why not.

LEDs have very fast (a small fraction of a second) on/off times. So the effect of a longer pulse width should be longer "on time" for the LED. And since our minds likely can't can't keep up with that "flicker rate", our minds should blur the on/off flicker together, and just perceive a longer on time as a brighter light, and a shorter on time (which corresponds to shorter FI pulses) as a dimmer light.
Anything over about 25 Hz and the eye/brain sees it as continuous.. That's why TV and Movie pictures seem continuous even though they are a series of still images..

You'll see some flickering of the LED at lower rpms most likely but you will still be able to tell whether the flicker is brighter or dimmer..

Play with the resistor values in the simple circuit I posted to find what makes the changes you are interested in most obvious to your eye.. For economy, you are going to want to have the shortest pulse widths to the injectors possible so you will want to adjust the resistor value to give most change in apparent brightness at short pulse widths.
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Old 05-14-2008, 11:14 PM   #44
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holy: "Which shop manual provides that info [DFCO]?"

The official Honda service manual, known as the Helms manual.

"I've been trying to find out if it [SG] measures fuel flow or if it calculates it, but nobody's been able to answer."

I think it's a hard thing to find out. But I found this statement (http://www.cleanmpg.com/forums/showthread.php?t=4495): "the instantaneous FE is calculated using air flow through the engine, not fuel actually consumed."

I also confirmed this when I figured out that OBD2 (the foundation of SG) doesn't monitor the injectors. And that's a confusing issue, because some makers (GM, I understand) do it anyway. But it's outside the formal OBD2 protocol, and is therefore typically unsupported in products like SG.

The folks who designed OBD2, in the early '90s, were thinking about things like emissions, but they weren't thinking about monitoring FE.

"You may have just saved me $160, though the SG is probably still convenient."

It seems that lots of people love it, but there are certainly some limitations.
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Old 05-14-2008, 11:14 PM   #45
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gary: "dropped in an old Proto 5/16-1/4 drive socket"

I figured that socket would eventually turn up. Could you please send it back to me?

"The glove box rattled when you drove at low rpm."

Funny you should say that. I think I have a similar glove box rattle. Seriously. The main obstacle in fixing it is that my wife can't drive a stick (and is also not good at diagnosing glove-box rattles). I need to sit in the passenger seat while someone else drives.

I guess I just need to wait for my kids to grow up. It's barely audible and happens rarely so I don't think about it much.

"the much higher AF ratio cancels out the advantage of larger throttle openings"

I tend to believe the opposite of this. But I need more miles to feel more sure. That will take a while, since my routine right now doesn't demand a lot of miles. But one way or another I'd like to address this puzzle.

"Lean burn does not work for 30 seconds after engine off coasting."

I read that too, but I think it's a bit of an overstatement. Anyway, with my WOT strategy, I rarely see lean burn, anyway.

"I try to downshift to keep engine speed above 1100 rpm"

I think the DFCO cutoff is 850. That's what the book says, and I verified that on my car, by observation with the DMM.

"It would be nice to be able to have an instant fuel economy reading to further improve my technique."

I think there should be a way to do that which is better than the current choices. But I don't quite see what the solution is.
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Old 05-14-2008, 11:15 PM   #46
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road: "Palm Pilot datalogger ..."

Those are some interesting citations you found. I had no idea there were so many different grass-roots efforts to solve this problem (log and display engine data in the best way).
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Old 05-14-2008, 11:15 PM   #47
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fume: "Play with the resistor values in the simple circuit I posted to find what makes the changes you are interested in most obvious to your eye."

How about this wacky idea: instead of producing light, why not produce sound? Vary the pitch or timbre of the sound, to correspond to the changes in pulse width. Then you can keep your eyes on the road. And if you insist on carrying passengers (after all, they hurt FE), it's easy enough to give them earplugs.

Actually, if you made the sound just quiet enough, it could be meaningful and helpful without being too annoying.

Using sound, you could also monitor multiple sensors. For example, the sound's amplitude could be an expression of AFR, and the pitch could represent pulse width.
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Old 05-15-2008, 05:56 AM   #48
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Monroe;

After driving 3500 miles I find my VX gets about the same mileage compared to 5 other cars which is close to the old EPA highway rating, or slightly better, About 56 MPG.

Highway driving the mileage is about 10-15% better depending on how much I can draft (which was not a part of EPA calculations).

When I bought my 06 Corolla (auto) I couldn't get the EPA highway mileage rating on a consistent basis. This was also the time when we got 10% ethanol here. There are no stations here that do not sell 10% ethanol.
Then the new ratings came out and it was 35 instead of 38 for the Corolla. I could get 35-37 using neutral coasting in local driving. I never tried to drive at lower speeds so the best highway mileage I ever saw was on a trip to Detroit where I managed 39 for one tank on the Ohio turnpike at 63MPH (cops all over the place writing tickets-also could have been no ethanol in the gas-it was mid range instead of cheap stuff).

My VX is of course a time capsule of sorts, with original tires. I like the idea of knowing exactly the potential of the car before I change anything. Only mod right now is reversing the intake snorkel to capture warm air from right behind the top radiator tank.

When I first got the car on the road I had two reasons to not worry about the mileage for the first few hundred miles. The fuel that was in the tank when I got it (about 3 gallons) and the fact the tank had a dent in the bottom from carrying the car around with a forklift which left a dent in the bottom of the tank. Air pressure fixed the dent, and after two tanks of driving I figured the 3 residual gallons had been diluted enough. Both of those circumstances considered, I still got 50 MPG on those first two tanks even not considering the fact that removing the dent increased tank capacity.

It would be nice to see instantaneous consumption figures, but it's not that important to me. I can read gaslogs of other and see what their mileage figures are, and how they achieve them. I can also calculate the savings if I used engine off coasting, but with the traffic congestion here I just don't consider it practical.

As long as I drive my routes and use my established routines my mileage is 55 local, 61 at 55-60 no draft, and 64 + drafting at 67.

I understand you are testing variables to see what works, I just looked at gas logs and driver notes. The hypermiling techniques I use are fairly mild and my priority is to not interfere with other drivers, but adapt to their actions and use them to my advantage.

I dont think knowing what my instantaneous mileage is at any point in time would change that much. It mat be a rationalization, but I dont think it would be possible to get the kind of mileage I reported without staying in lean burn a significant portion of the time. In fact I think you can determine when you are in lean burn using the shift indicator light, by accelerating just enough to keep it off. I found out when it comes on you can put it out by giving the car more gas, and that is exactly what I am learning to do, apply the minimum amount of throttle that keeps the light off, which should keep me in lean burn.

regards
gary
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Old 05-15-2008, 06:25 AM   #49
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Originally Posted by monroe74 View Post
How about this wacky idea: instead of producing light, why not produce sound? Vary the pitch or timbre of the sound, to correspond to the changes in pulse width. Then you can keep your eyes on the road. And if you insist on carrying passengers (after all, they hurt FE), it's easy enough to give them earplugs.

Actually, if you made the sound just quiet enough, it could be meaningful and helpful without being too annoying.

Using sound, you could also monitor multiple sensors. For example, the sound's amplitude could be an expression of AFR, and the pitch could represent pulse width.
That wouldn't be as hard to do as you might think and would probably work..

What you would need to monitor injector pulse width would be a speaker output transformer used to drive small speakers.. An 8 ohm to 1K ohm transformer would do it, I think I have one in my junk box (more like a room actually ).

What you would do is connect the 1K side windings across the injector and a speaker to the 8 ohm side.. The pitch of the sound output would change with the rpm of the engine and the tone or timbre of the sound with pulse width.

You would probably have to put a resistor in series with the transformer leads on one side or the other to keep the volume down..
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Old 05-15-2008, 10:13 AM   #50
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There's a lot of information about a DIY computer over on ecomodder.com. Parts look to be about $80... worth looking into!

http://forum.ecomodder.com/forumdisp...mputer-26.html
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