Now up to 57.3 mpg at 60 mph in my 97 Saturn SC1

[cheapybob]

This is a real old thread. My plugs said i was running too lean, and i found out that the scangage doesn't actually monitor fuel used, but rather the fuel it thinks should be used, so I stopped using the resistor cheat. The fact that it ran TOO lean says it really did affect the mixture, but I didn't want it running TOO lean.

I recently cobbled a 2 sensors in parallel + resistor setup as suggested by froggy and it allows me to feed the computer a reading about 10% higher than actual, which I think will give me a mixture thats a little lean, but not to the point of being a problem, and that's what i was looking for. I haven't driven with it long enough to make any comment on whether it solves everything though.

[theholycow]

I would expect the ScanGauge to figure in the leanness when it calculates fuel rate. I assumed it used MAF and O2 to figure fuel rate.

I wonder what sensors it actually uses, then...

[cheapybob]

Originally Posted by theholycow

I would expect the ScanGauge to figure in the leanness when it calculates fuel rate. I assumed it used MAF and O2 to figure fuel rate.

I wonder what sensors it actually uses, then...

I'm guessing it uses rpm/mi and displacement and intake temp calculating at a 14.7 to 1 A/F ratio. There was a thread about that a year or so ago. search for scangage or scangauge.

Anyway, to remove any doubt as to whether it was right or wrong, the correct solution is to fill the tank before and after and use the mileage to determine overall mpg for the tank, and compare it to the scangauge value, and recalibrate if necessary. That's what I'm going to do. Then there can be no question as to whether it was right or not.

[Project84]

Cheapybob, you may have started something here. I was at the junkyard today tracking down all the ECTS I could find and as I'm going through each Saturn, I notice IAT Sensors are all missing (I remember taking a few of them, but there were about 12 Saturns there) as well as a lot of the air intake tubes and boxes were missing. I'm guessing you're brought to light an easy enough mod that many people are interested in trying it themselves.

Not crediting you for the HAI or anything, but something must explain why the Saturns all had signature parts missing.

[theholycow]

That method still leaves question about instant measurements. It only tells you if the SG is accurate on average.

I'm not trying to down the SG; it's a great tool and it totally deserves the credit it gets. However, I just think there are some conditions in which its live MPG calculations can be wrong even if the average comes out the same, and that people should be aware of that.

[cfg83]

theholycow -

Originally Posted by theholycow

That method still leaves question about instant measurements. It only tells you if the SG is accurate on average.

I'm not trying to down the SG; it's a great tool and it totally deserves the credit it gets. However, I just think there are some conditions in which its live MPG calculations can be wrong even if the average comes out the same, and that people should be aware of that.

110% agreement. The Scangauge has to be a JOAT/MON (Jack Of All Trades/Master Of None), so it has to compromise. It is working with the OBD-II specification, which every car company has implemented as they see fit. I consider it to be *the* training tool for people who want to learn how to Hypermile. It ain't cheap, but it pays for itself (even faster than it used to with these gas prices!!!).

CarloSW2

[cheapybob]

Originally Posted by theholycow

That method still leaves question about instant measurements. It only tells you if the SG is accurate on average.

I'm not trying to down the SG; it's a great tool and it totally deserves the credit it gets. However, I just think there are some conditions in which its live MPG calculations can be wrong even if the average comes out the same, and that people should be aware of that.

I can't disagree there, but given that there is nothing better out there, its what I bought, and I've got to live with what it provides. The best test I could do would be to find a 50 mile stretch of very flat road with a gas station at each end and no lights between, but at what cost to get there, do the 50 mi, and get back.

I have to figure if the scangage is accurate over a 300 mi fillup, it should be at least reasonably close, normally. I think that's about the best I'm going to get because I don't have any way to get fuel injector pulse data, which is what we should really be using to calculate MPG's. And if the fuel usage adjustment stays steady for a few tanks, then I have to think any readjustment for learning has taken place, and it is reasonably close.

BTW, my car usually goes into closed loop within 2 blocks of my house, so I'd guess that open loop runtime is minimal.

[theholycow]

Well, there IS a way to get fuel injector pulse data, but I'm not sure if it would be possible to get it into the SG. There's a link in my sig for a fuel rate monitor. Another user, fumesucker, has hooked up the same thing with a computer's microphone input instead of a dwell meter, resulting in the ability to log and view a graph of injector pulses.

I think it could be possible to get the data into a ScanGauge by finding a sensor you can abuse, converting injector pulse width to match the type of data that sensor would provide, and then making an X-gauge in the SG...but I am not smart enough to accomplish that hack.

[cheapybob]

ANYTHING is possible, but getting there is never easy. The built in Heads Up display and Driver Info Computer on my 92 Grand Prix had no problem tracking MPG and DTE, and had no adjustment factor you could play with. The newer Corvettes and Caddy's also have similar systems, I assume connected to the engine computer, so that leads me to believe that maybe the short term fuel trims might have the data needed, but I wouldn't have a clue how to use it.

[mamalujo2003]

Originally Posted by cheapybob

This is a real old thread. My plugs said i was running too lean, and i found out that the scangage doesn't actually monitor fuel used, but rather the fuel it thinks should be used, so I stopped using the resistor cheat. The fact that it ran TOO lean says it really did affect the mixture, but I didn't want it running TOO lean.

I recently cobbled a 2 sensors in parallel + resistor setup as suggested by froggy and it allows me to feed the computer a reading about 10% higher than actual, which I think will give me a mixture thats a little lean, but not to the point of being a problem, and that's what i was looking for. I haven't driven with it long enough to make any comment on whether it solves everything though.

Hey Bob, I'm new to all of this. I would like to know how you wired the sensors and resistor. I don't know what 'parallel" means when it comes to electronics. Do you have any pics, or could you share step-by-step instructions on how to do it?