Average MPG Duration

[Big L]

I found on another thread that Bill said the Gryphon uses 100,000 samples at 1 second apart to determine average miles per gallon. That is supposed to equal about 4 tanks of gas. I do not think that is the case with my Gryphon.

The reason I think this is because it will usually drop a good 3 to 4 tenths sitting at a light for a minute or so. With 100,000 samples you shouldn't see that kind of drop for that duration.

My questions are:

How many samples does the gryphon actually use and how far apart are they?

How can I increase the ammount of samples it uses?

Thanks

[Longshot270]

Originally Posted by Big L

I found on another thread that Bill said the Gryphon uses 100,000 samples at 1 second apart to determine average miles per gallon. That is supposed to equal about 4 tanks of gas. I do not think that is the case with my Gryphon.

The reason I think this is because it will usually drop a good 3 to 4 tenths sitting at a light for a minute or so. With 100,000 samples you shouldn't see that kind of drop for that duration.

My questions are:

How many samples does the gryphon actually use and how far apart are they?

How can I increase the ammount of samples it uses?

Thanks

The gryphon will keep recording until the alotted memory is filled up. Unfortunately the only way for it to increase the number of samples is to run longer. Otherwise it would be just as accurate as the instant mpg. It will keep taking one reading every second. (But I'm not sure since the data log will take 5 per second)
Instead of looking at it as 4 tanks which can run out quicker depending on where/how you drive consider the memory full after 28 hours of driving. If you have a 30 minute commute to work, after a month you'll have your average.

If you accidentally cleared the average mpg then you lose all those samples the programmer uses for refrence. There are a few ways for that to happen. One is to hit the enter button twice, but the most common is to have the programmer get unplugged or have the power taken away some how.

[Big L]

Thanks for the reply Longshot.

What you are telling me is the same that I heard before. About 28 hours of driving will compute the average. I am just questioning the accuracy of this. I don't see how a couple minutes of idling can effect the AVG MPG to the extent it does with 28 hours of samples.

I know what you are thinking. "He must have reset the AVG MPG or something." I can assure you this is not the case.

Hasn't anybody else noticed how it will drop quickly while idling? Is it just mine? The other day I was picking up my kids and idled for about 6 minutes and the AVG dropped over 2 mpg. Just doesn't add up to me.

[AZFX4]

My honest opinion is the Average MPG and Instand MPG is BS.

I did a 660 mile trip to Cali for a F150 meet few months back. It showed I averaged 14.7 mpg, filled up and hand calculated it. 14.3 mpg. It always shows high.

My truck showed I averaged 14.8 mpg my last tank. I hand calculatd it, it came out to 13.4 mpg.

I filled up, went offroading.. mashing the gas, having fun. Showed me 13.4 mpg, got on the interstate (75mph speed limit) it jumped to 15.9 - 16.0 average mpg. It's never been over 15.8 mpg average except GOING to Cali it showed like 16.6 mpg and dropped constantly to 14.7 - 14.8 mpg doing the same speed for atleast 200 - 250 miles at a time to each gas station.

The slower I go, the worse my average mpg shows. Harder I drive it, the better it shows.. My tires are stock size, stock gearing. So it shouldn't be off.

Sitting at a light it will drop from like 14.8 mpg to 14.4 mpg just idling. Or cruise control doing 70 mph and I gun it to pass someone it drops like 3 tenths..

I keep forgetting to change it to another parameter. Watching it is silly.

[Jackpine]

I don't really know what to say to you guys. Bill Cohron is responsible for much of the software/firmware in the Edge/Gryphon and when he states the Avg Econ uses 100,000 samples, I have to believe him. I know when I used to monitor it, the Gryphon's value would stay more constant than my dashboard message center's readout, which tells me the dash readout DOES use a smaller sample size.

And, in my case, sometimes the dash readout would be exactly what I would "hand calculate", at other times it would be a bit high. The Gryphon was always higher.

I HAVE determined that when my "low level warning" comes on, I have about 60 miles of gas remaining, assuming normal fuel usage rates (and how much I was able to put into the tank when this happened).

I really don't monitor Avg or Inst Econ anymore. I just use the trip odometer feature in the dash and the gas gauge itself.

- Jack

[Longshot270]

Well you dont necissarily need to reset it for it to move. I figured you were talking about sitting at a light for 30 seconds. Lets say you have 1200 readings(20 minutes) of 17 mpg. Average in 360 readings (6 minutes) of 0 mpg or idle and you end up with about 13 mpg. If you had an hour (3600 reading) of 17 mpg driving you would still get dropped to 15.5 avg mpg.

And this was using an average of 17 mpg because I've heard of better and worse averages (and its pretty much what mine gets), if you went up a hill and had to give it some gas, that could lower the sample for those few seconds. Averaging that with a zero will make an even bigger impact.

[88Racing]

My readings are continuously high also.
The same thing happens when sitting at a light the read out drops only about .1-.2mpg.
On the other hand when I get into it my average goes up by 3-5mpgs then after about 10 miles of hwy driving it levels back out.
I'll stick with the hand calculations over the digital readouts any day.

[AZFX4]

There is alot of people saying it reads high and it drops alot when idling at stoplights or what not.

[Jackpine]

Originally Posted by AZFX4

There is alot of people saying it reads high and it drops alot when idling at stoplights or what not.

And, if we're at the "stabilized" 100,000 sample calculation, all we're doing is multiplying by 100,000, adding zero and then dividing by 100,001 each second. Doesn't look to me like much would change.

After 30 seconds of zero mpg at a stoplight, and assuming a "stabilized" Avg Econ reading of 15.5, the equation is: 15.5 x 100000 / 100030 = 15.49535, which "rounded" is still 15.5. And I still get 15.49071 after 60 seconds. After 2 minutes, it's 15.48142, which is still "15.5". At this rate, looks to me like we could sit for at least 5 minutes, before we'd see 15.4.

Maybe the Mad Doctor will enlighten us when he returns.

- Jack

[88Racing]

So if a person typically resets after every tank they are not getting the full effect of the AVG MPG. They should wait and reset after 4 tanks? Or don't reset at all?
The only reason I bring this up is if a person does reset it at every fill up then there would be less samples to draw from thus sitting at an idle would have a bigger drop? Am I applying the right reasoning?