SGII first observations!

[Old Tele man]

...OK, I performed an initial GALLONS "offset" calibration; and here are some 'semi-scientific' results (26.2 miles each way):

DAY #1 -- 32.0 mpg at 37-deg.F going TO work at 6:00am.
DAY #1 -- 38.2 mpg at 60-deg.F coming FROM work at 5:30pm.
DAY #1 -- 35.1 mpg avg.

DAY #2 -- 32.3 mpg at 42-deg.F going TO work at 6:00am.
DAY #2 -- 38.8 mpg at 67-deg.F coming FROM workat 5:30pm.
DAY #2 -- 35.6 mpg avg.

DAY #3 -- 33.5 mpg at 49-deg.F going TO work at 6:00am.
DAY #3 -- 38.3 mpg at 63-deg.F coming FROM work at 5:30pm.
DAY #3 -- 35.9 mpg avg.

DAY #4 -- 34.4 mpg at 48-deg.F going TO work at 6:00am (drizzling).
DAY #4 -- 36.1 mpg at 52-deg.F coming FROM work at 5:30pm.
DAY #4 -- 35.3 mpg avg.

DAY #5 -- 33.3 mpg at 45-deg.F going TO work at 6:00am.
DAY #5 -- 40.0 mpg at 68-deg.F coming FROM work at 5:30pm.
DAY #5 -- 36.7 mpg avg.

DAY #6 -- 35.1 mpg at 46-deg.F going TO work at 6:00am.
DAY #6 -- 39.3 mpg at 71-deg.F coming FROM work at 5:30pm.
DAY #6 -- 37.2 mpg avg.

DAY #7 -- 36.4 mpg at 53-deg.F going TO work at 6:00am.
DAY #7 -- 40.7 mpg at 55-deg.F coming FROM work at 5:30pm.
DAY #7 -- 38.6 mpg avg (!).

DAY #8 -- 33.7 mpg at 45-deg.F going TO work at 6:00am.
DAY #8 -- 37.2 mpg at 66-deg.F coming FROM work at 5:30pm.
DAY #8 -- 35.5 mpg avg.

DAY #9 -- 34.1 mpg at 45-deg.F going TO work at 6:00am.
DAY #9 -- 38.5 mpg at 66-deg.F coming FROM work at 5:30pm.
DAY #9 -- 36.3 mpg avg.

DAY #10 -- 34.6 mpg at 43-deg.F going TO work at 6:00am.
DAY #10 -- 40.7 mpg at 73-deg.F coming FROM work at 5:30pm.
DAY #10 -- 37.7 mpg avg.

...which produces the linear regression analysis (for this car):

MPG = 0.23*(temp) + 24, with RR = 0.82

...finally, the tank MPG is the average of the individual trip MPG's, ie:

MPG(tank) = [ MPG(trip.1) + MPG(trip.2) + ... + MPG(trip.N) ] / N

...and, the average of the 10 averages was 36.4 mpg while the actual tank-fill value was 35.6 mpg, which is 98%--that's just a 2% error...close enough!


addendum: SGII indicated 9.7 gallons used while the tank-fill was 9.736 gallons!

[Piwoslaw]

Wasted money on a ScanGauge...
Just kidding

[janvos39]

Piwoslaw Lucky for you. I have not been able yet to find instrumentation for my Ford Focus Diesel - maybe I must change Ford for a better known brand LOL.

[Piwoslaw]

Originally Posted by janvos39

Piwoslaw Lucky for you. I have not been able yet to find instrumentation for my Ford Focus Diesel - maybe I must change Ford for a better known brand LOL.

I think you misunderstood me. I was saying that Old Tele Man wasted money on a SGII which didn't show him anything new. Of course, it was a joke

I'm still ScanGauge-less, but my Peugeot does have a factory installed fuel consumption gauge. It's usually off 0.5-1l/100km, but it'll have to do until I get my hands on the SGII. If only they were cheaper outside of North America...

[Jethro]

I would really like to purchase one for my Nissan. However, I'm going to spend the $200 on satellite radio first. Living in the mountains means no radio (well, clear channels anyways)

[Arragonis]

Thats a pretty detailed log. I've kept a mental one of my built in MPG readings and on the way out its usually 45 and back is usually 55. Average is just under 50 (see success stories) so it seems reasonably close.

Piwoslaw - how did you determine the scale of the error on your built in meter ?

[Piwoslaw]

Originally Posted by Arragonis

Piwoslaw - how did you determine the scale of the error on your built in meter ?

The factory instrumentation has two resetable modes (which I reset after each trip and each fill up, resp.) and an instant consumption mode. Each trip and each fill up is noted (distance, l/100km, avg km/h, where I went, weather and/or traffic conditions if out of normal). After each fill up I do the math and compare the fuel/distance with the l/100km for that tank. Since in both cases I use the car's odometer I don't have to factor in the 5% difference between odo and GPS (that comes later). I've also noticed by doing even more math that the individual trips don't add up to the tank, but that may be b/c of the computer rounding up or down after each trip reset.

At the Peugeot forum I found out that pretty much everyone's onboard fuel computer is off by 0.5-2l/100km, some are too high, others too low. The funny thing is that the differences between the car's comp and actual fc varies with each tank. The difference may depend on the number and length of trips in each tank, but my investigations haven't gone that far.

I understand that a ScanGauge can be calibrated, so after a few tanks it should be right on? I guess that when my consumption gets even lower I'll need the SGII to refine readings, since the comp seems to be off by more when my fc is lower. And USD/EUR is still fluctuating in the wrong direction

[Arragonis]

Thanks - useful info. I've looked into getting one into the UK but as you say the exchange rate is not favourable - especially not the GBP. Its also hard to justify the additional cost over the factory unit but I understand it gives more info which may be useful later.

[Dave's Civic Duty]

The Mrs. bought me a SGII for Christmas for my truck, but since my last tank gave me 47 for my VX, why drive the truck? I'm going to have to get my book out an read how to set the SGII up. It's a nice piece of equipment. Even if I take it easy, from a standing start, I'm only getting 3 MPG in my diesel. but goes up accordingly.

Glad I got one!
Dave
So many toys, too little time. At least it feels that way!

[Unforgiven]

(stares at the mathematics at the bottom of the initial post........... smoke starts to roll from ears and eyes glaze over) ow.

Heh, nice even if I am not understanding it, ah well.