Request for Data from TheHolyCow

[theholycow]

Originally Posted by dosco

For most driving, my perception is that the throttle angle is damn close to being the same.

It is most likely that your perception is very wrong.

The ELM327, if you have a laptop you can use in the car, is far cheaper than a ScanGauge and will get you the information you need, as well as logging it. Perhaps that can help you find the best practices for your car? They go for under $30 shipped on eBay.
http://search.ebay.com/search/search...e=260258247681

[dosco]

Originally Posted by theholycow

It is most likely that your perception is very wrong.

For sure.

"The easiest person to fool is yourself." - Richard Feynman

The ELM327, if you have a laptop you can use in the car, is far cheaper than a ScanGauge and will get you the information you need, as well as logging it. Perhaps that can help you find the best practices for your car? They go for under $30 shipped on eBay.
http://search.ebay.com/search/search...e=260258247681

Hell, I might just do that as well.

I see they're about the same price on the ELM website. What obviousness am I missing?

[theholycow]

Originally Posted by dosco

I see they're about the same price on the ELM website. What obviousness am I missing?

Maybe I missed something, but I thought the ELM website only sold the chip, not complete ready-to-use built units.

Also, I had funds in PayPal.

[GasSavers_BEEF]

honestly, a scangauge was one of the first FE mods I bought. it will tell you what the TPS (throttle position sensor) is saying and also the load on the engine. I would bite the bullet and get the SG.

I don't know a lot about the other device you are talking about but don't you need a laptop for that? not that it is bad but it is a lot easier to have the little 1x4 inch scangauge on the dash than a laptop. there again I may be in left field

[dosco]

Originally Posted by theholycow

I thought the ELM website only sold the chip, not complete ready-to-use built units.

Uuuhh, yeah, that could be it.

[theholycow]

Yup, you need a laptop, or if you spend a little more you can use it with a PDA or some cell phones (even then it's still a fraction of the cost of a SG). No matter what it's not as convenient or as nicely packaged as the SG.

It does offer additional functionality (logging), though, and I think I may be able to combine it with real fuel injector pulse width data.

[monroe74]

Just chiming in late on this very interesting discussion.

Originally Posted by theholycow

I stand by this statement:
"At 2000rpm and 20% throttle it will use the same amount of fuel regardless of gear."

I think you're getting right to the heart of the matter with that statement, but I think confusion is invited because your phrasing is ambiguous.

When you say the "same amount of fuel," I think you're leaving it unclear as to whether you mean 'same amount of fuel per unit of time' as compared with saying 'same amount of fuel per unit of distance.' The former is true. The latter is not.

In other words, "2000rpm and 20% throttle" will always use the same number of gallons per hour, regardless of gear (and vehicle speed). But if I change gear (while maintaining 2000rpm and 20% throttle), vehicle speed will change. Since I am changing MPH while holding GPH constant, MPG is going to change.

Originally Posted by theholycow

It does offer additional functionality (logging), though, and I think I may be able to combine it with real fuel injector pulse width data.

I agree with you that logging could potentially be very helpful, although I'm still trying to figure out the best approach to that. I also think you have a very good idea about integrating injector data somehow, so I look forward to hearing more about that.

[theholycow]

Well, my idea for integrating injector data begins here:
http://www.gassavers.org/showthread.php?t=7608

I just have to find a way to make the sound file into a stream of simple numeric data describing pulse width/duty cycle, and maybe average the amplitude for each pulse (though that should be pretty consistent). I don't know if it's beyond my abilities or not. Once that's done it should be a piece of cake to combine it with OBDII data. I'm not really sure why, though; I don't think there's much more for me to learn about my car by doing it...it's just an idea I have.

[monroe74]

"I'm not really sure why"

The point of looking directly at the injectors is that it might be much more accurate than the data OBD-II provides. But I think this would only be an issue on certain cars, under certain conditions. So I can't claim it's a universally valuable thing to do. I just don't know for sure.

[theholycow]

Oh, I know that's a good reason why to look at the data, but I already do that in realtime with the meter. What I'm not sure of is why I want to log it and lace it together with OBDII data. I guess that'd be so I can look at it compared to the other data, to answer questions like the one at the top of this thread.