Gryphon Average Econ WAY Off...
#1
Gryphon Average Econ WAY Off...
Anybody else have this problem with their Gryphon or Edge? The Average Economy PID is WAY off, like 3mpg off. The first tank I ran through the truck with it it was a couple MPG lower than what it was, and all the subsequent tanks of fuel (5 or so, with a few towing) the Gryphon has been 3MPG high. Like it will say I'm getting 16.5-17mpg, and I'll fill up and only have gotten 13.5. It hasn't been correct once.
And yes, I reset the Gryphon's econ each time I fill up, and yes I reset the Gryphon for my tire size, and double checked it versus a GPS.
So anybody else have this problem?
And yes, I reset the Gryphon's econ each time I fill up, and yes I reset the Gryphon for my tire size, and double checked it versus a GPS.
So anybody else have this problem?
#3
#4
I'm going to agree with mx here. I have never once reset my average econ, and mine is always fairly accurate. Within 1 mpg or so of my calculations almost every time.
At first, it was way off, it settled down a bit after I put some miles on it. Just a guess though, really not sure. Not very familiar with this yet.
At first, it was way off, it settled down a bit after I put some miles on it. Just a guess though, really not sure. Not very familiar with this yet.
Last edited by MercedesTech; 03-03-2009 at 03:01 PM.
#5
An average is an average though... it shouldn't matter how long its run for. If I want it to average the fuel consumption of 10minutes of driving it should be doing that, or if I want an average of each tank or an average of a years worth of driving. The amount driven shouldn't make any difference in the average economy.
#6
Don't know what to tell ya. I agree, but doesn't mean thats how it works.
I think this would be better answered over here:
http://dygytalworld.ehost-services139.com/forums/
Or talking to Bill or Corey directly. They will always have the best answer for their product.
I think this would be better answered over here:
http://dygytalworld.ehost-services139.com/forums/
Or talking to Bill or Corey directly. They will always have the best answer for their product.
#7
An average is an average though... it shouldn't matter how long its run for. If I want it to average the fuel consumption of 10minutes of driving it should be doing that, or if I want an average of each tank or an average of a years worth of driving. The amount driven shouldn't make any difference in the average economy.
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#8
#10
Interesting to see the different responses here. The average MPG on my Gryphon is off by about 2 MPG too. Usually too high. From watching it, I'm guessing it shows you the average MPG in a previous 10-minute "window". I base that on how quickly it will change while stopped at a light as mxracer pointed out or how rapidly it increases if you coast down a long hill.
My truck also has an information center that shows average MPG, and it changes much more slowly, sort of like its window is the last hour of driving. And the info center's MPG is usually quite close to what I get doing a hand calculation at fillup.
- Jack
My truck also has an information center that shows average MPG, and it changes much more slowly, sort of like its window is the last hour of driving. And the info center's MPG is usually quite close to what I get doing a hand calculation at fillup.
- Jack
#12
Bill at PHP explained it all to me when I was up there for a live tune. He said it really wasn't close to dead on until you ran about 3 full tanks through it. He explained to me about the sitting at a stop light thing, it may look like it drops early but it eventually compensates itself out, I'd try to explain more but I was half driving/half listening to him when he was explaining it. Would hate to get some facts wrong, but nonetheless, mine's a little off too on a highway trip. I usually get better gas mileage than the gryphon indicates on a long highway trip, as for my daily commute to/from work, it's pretty dead nuts.
#13
An average is an average though... it shouldn't matter how long its run for. If I want it to average the fuel consumption of 10minutes of driving it should be doing that, or if I want an average of each tank or an average of a years worth of driving. The amount driven shouldn't make any difference in the average economy.
#14
I definitely have to agree with this...My average did not get close until I had stopped reseting it. When I was reseting it each time it was showing about 2.5-3 mpg higher.
#15
We covered this in other threads before but I'll go over it again.
The Average Economy function uses a cumulative average of 100,000 samples. When you reset, the sample count goes to zero and moves up from there. Something like this
((Current Average * Sample Count) + Current MPG) / (Sample Count + 1)
Sample 1: 16.24 - Avg: 16.24
Sample 2: 16.16 - Avg: 16.20
Sample 3: 15.88 - Avg: 16.09
Sample 4: 16.36 - Avg: 16.16
...and so on. Samples occur about once a second. Once it hits the 100,000 mark, it then runs off a stabilized average value. The calculated number of samples is clamped at 100,000 and the latest MPG value is figured in and divided back out. Without having to store every single sample value, this is the most efficient and accurate way calculating the average.
When you consider that 100,000 samples (at 1 per second) comes to almost 28 hours of run time and 60 MPH at 15 MPG equals 4 GPH, you would have to use 112 gallons of fuel to fill the "Average Buffer", or roughly 4 tanks which is why the longer you go between resets the more accurate the readings are.
***
One final though as well is that all the calculation for fuel economy are based on the specific density of gasoline. Anything that changes this density and the resulting mass of fuel being injected is going to change the calculations for fuel economy. Ethanol and "Winter Blend" or oxygenated fuels will all have an adverse effect on fuel economy ratings and is not taken into consideration by the programmer.
Take care.
The Average Economy function uses a cumulative average of 100,000 samples. When you reset, the sample count goes to zero and moves up from there. Something like this
((Current Average * Sample Count) + Current MPG) / (Sample Count + 1)
Sample 1: 16.24 - Avg: 16.24
Sample 2: 16.16 - Avg: 16.20
Sample 3: 15.88 - Avg: 16.09
Sample 4: 16.36 - Avg: 16.16
...and so on. Samples occur about once a second. Once it hits the 100,000 mark, it then runs off a stabilized average value. The calculated number of samples is clamped at 100,000 and the latest MPG value is figured in and divided back out. Without having to store every single sample value, this is the most efficient and accurate way calculating the average.
When you consider that 100,000 samples (at 1 per second) comes to almost 28 hours of run time and 60 MPH at 15 MPG equals 4 GPH, you would have to use 112 gallons of fuel to fill the "Average Buffer", or roughly 4 tanks which is why the longer you go between resets the more accurate the readings are.
***
One final though as well is that all the calculation for fuel economy are based on the specific density of gasoline. Anything that changes this density and the resulting mass of fuel being injected is going to change the calculations for fuel economy. Ethanol and "Winter Blend" or oxygenated fuels will all have an adverse effect on fuel economy ratings and is not taken into consideration by the programmer.
Take care.