inventor of the ScanGauge
 

I had a phone conversation this morning with Ron DeLong, SG inventor. This was with the intention of writing a page for MetroMPG.com that delves a little into the background of the guy who makes every fuel saver's favourite toy.

Very friendly guy, happily chatted with me for 30 or 40 minutes about a whole range of topics. We talked a bit about his work & education background, what makes him tick, how the SG came to be, some of the challenges and a few future plans for the magic little box.

So what I'm wondering is: does anyone here have anything specific they want to know before I write this up? I mentioned to Ron I'd likely send some supplementary questions by e-mail. So now's a good chance to get them in.

I think most here, including myself, would like a little more insight into how the SG II computes idle and closed-throttle fuel consumption, and whether or not it's necessarily accurate.

For example, coasting down from high speed in gear with the engine on in my car, the SG II indicates a fuel consumption indicative of the idle speed; other forum members have suggested it's very likely that no fuel is being consumed.

Others have suggested that the SG II may not be accurately recording fuel consumption during a key start, in which case the fuel consumption may be substantially off when key start P&G is used a lot. Some insight into any potential inaccuracy in this situation would be helpful as well.

I did ask about fuel-cut specifically, and the answer was: cars which do have overrun fuel cut do not all report it the same way. IE - some continue to calculate and report injector pulse width despite the injector(s) itself being inactive (he speculated that this is so "reignition" will be smooth).

On that point then, you should believe what your service manual says about fuel cut-off on overrun, not the SG. (Which raises a question: will an auto tranny will do fuel cutoff? What would keep the motor spinning if the TC isn't locked up?)

He also emphasized that the difference between the SG and the other OBD products on the market is the amount of time & programming effort his company has put into the fuel consumption calculations, so he's understandably protective about revealing specifics.

He also said that a significant amount of time is spent "debugging" cars which don't all follow the same rules, in terms of OBD2 communication. IE the cars that follow the "expected" programming do show "9999" mpg on fuel cutoff. (Mine happens to be one of the cars that doesn't, even though my service manual says it has that feature). He also estimates the effect on accuracy of not factoring that condition into fuel economy calcs is probably about 0.1%.

On My 98 metro, sg2 indicates that the car is going into open loop when decelerating in gear (which isn't very often) , car warm, throttle closed. is this an indication that fuel cutoff has occured?

I tried to find the Metro conditions when fuel cutoff occurs, but couldn't.

I'm guessing that's what you're seeing, but it would be nice to be able to compare it to when the car is "officially" supposed to be doing it.

It makes sense: If the car were still in closed loop when the injector shuts off, the computer would probably have a hissy fit because the O2 sensor information would be showing a value very definitely non-stoich. By flipping into open loop, it's basically saying: ignore the O2 sensor until I tell you otherwise.

I don't remember whether this has been covered elsewhere for the SG2, but is there a way to capture a loggable output?

I want to know why they only make a product for OBD2 and not OBD1, look at the top ten cars, 70% were made between 1990 and 1995, only 30% were made after 1996 and would work with the scangauge, if this is an acurite representation of people who are interested in a product like this then 70% of the potentel custemers are being left out, I personaly would spend $200 on a scan gauge this very second if it worked on my car.

There's a plan to add a removable SD card to the SG2. So you'll be able to log data. There's also a USB connection in the works. It was supposed to be ready in '06, but they're running behind on that feature.

Maybe Ron knows?

I asked about this too. In a nutshell: they've considered it, but they've got their hands full with the OBD2 product (in a good way).

Part of the problem of going OBD1 may be that it increases the amount of variability to getting a one-size-fits-all magic box. Doing it with OBD2 is apparently enough of a challenge.