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Discussion Starter · #1 ·
Does any one know who to stop the average MPG reset after each single fill up.?

It would be nice if you were able to see your average MPG after 1000 miles or longer.

Thanks for replying.
 

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It's a very high-tech method. Dunno if everyone is up to it, but the tech savvy among us maybe could. It's paper and pencil! ;)
 

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Sanny said:
It's a very high-tech method. Dunno if everyone is up to it, but the tech savvy among us maybe could. It's paper and pencil! ;)
You mean ... cipherin'? You're making my head hurt!

It's also pretty easy to get a database or spreadsheet program to do this for you.
 

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mine doesn't reset automatically! I always have to push the button to reset the average... 2005 model. strange. very strange.
 

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dbw784 said:
mine doesn't reset automatically! I always have to push the button to reset the average... 2005 model. strange. very strange.
Strange. You know you have to move after filling up for it to reset? Mine normally takes a few meters, but then resets.
 

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once, my Prius didn't reset because I moved for 5-10 seconds and stopped again. I don't know if it is possible to repeat that or not....
 

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dbw784 said:
mine doesn't reset automatically! I always have to push the button to reset the average... 2005 model. strange. very strange.
I'll bet you a plug quarter you're mistaken.

2 conditions are required to trigger the auto-reset and some folks are too impatient and/or didn't realize what's required.

I would estimate that my reset occurs about 30 seconds after start-up when I fill the tank. Here are the conditions.

The fuel guage must advance to full (note that if you do not put in more than about 4 gallons the guage will not reset). This takes a while in the Prius and isn't like most cars that the analog guage just pops up to full when you start back up.

Then, the wheels must turn one full revolution.

So, my usual scenario.....

I fill up, I praise the Gods of Prius for yet another low gas bill, I get in, start up, hit the EV button and roll over to the stop sign at the intersection to get on the main road.

By the time I stop the guage is usually at ~1/2 full and climbing slowly. The MPG average has not yet reset. While I wait the guage gets to full....the MPG average still will not reset.

Once the light changes I start forward and low-and-behold the MFD MPG average and miles traveled resets.

I'm aware of folks that can jump right on the road and soar to highway speed and will often travel 1/2 mile or more before the reset occurs. Some of those people also thought that their MFD would not auto-reset b/c it hadn't despite the fact that they had moved pretty far from the pump. So they'd gotten in the habit of hitting reset manually not realizing it actually was working.

And here's the funny part....If you do manually reset at the pump before the fuel guage shows full it will reset, again, once the guage reaches the full mark and then the wheels turn a full revolution.

Check it out next fill up!
 

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mrv said:
or trade in your 2004+ Prius for a Classic Prius that doesn't automatically reset on you at a fillup. ;-)

Anyone know of anyone that has done this? Gotten rid of a 04-05 for a 01-03, I mean?
 

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efusco said:
Then, the wheels must turn one full revolution.
I 've read a post saying it will reset even when car is stationary. The driver did not power off during refueling! He mentioned seeing the bar increasing during refueling and while waitng in his car, it reset even before moving off.

I wonder whether it is time-dependent? :? Can anyone confirm this? :?:

Vincent
 

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If you've got the BT-Phone lockout defeat, I remember reading that, if you leave it on, as in, making the Prius think its always stopped, the mpg screen won't reset. I haven't tried it myself, but I remember reading it.
 

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I think my question is a bit vague. :oops: I 'll give it another try.

Sorry, I'm not suggesting leaving the car on while refueling. What I'm curious to know is why the wheels must turn one full revolution?

The reason why I suspect it is time-dependent is because the car computer must do some sort of averaging for the fuel level. We know that the fuel is sloshing around in the fuel tank during accelerating, decelerating, cornering or travelling on a slope. As can be seen from Attila's CAN captures, the fuel sender is always providing large variations of raw data to the computer. The computer must then do some processings before displaying it.

I found an old patent which may or may not be relevant to Prius.

http://www.freepatentsonline.com/4402048.html

In this patent, each sample is taken once every 30 secs. and after 4 samples have been taken, ie. 2 mins, the computer will determine an average value and send it to the display unit.

So if Prius were to follow the same algorithm, then we should expect the reset to occur at a preset time after power on upon refueling.

If this is true, then perhaps if you power on/off at the correct instant and sequences, you might be able to prevent the reset.

Just my $0.02.

Vincent
 

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That or to give you time to make your recordings before it resets.

I usually have the car in Ig-On or Ready after refueling, taking OD reading, trip B reading, MFD MPG, then calculating MPG. Then I reset trip B, reset MFD, and I am on my way. By that time, the gas guage is showing full.
 
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