Prius Fuel tracking

<div class='quotetop'>QUOTE(DaveinOlyWA @ Nov 21 2006, 09:13 AM) [snapback]352456[/snapback]</div>

I honestly don't know. It was something I was taught when I first started driving a very long long time ago. I think it has to do with condensation & sediment at the bottom of the tank but not sure. Then again it could just be they didn't want to come & get me if I run out of gas.

 

<div class='quotetop'>QUOTE(jkm750 @ Nov 19 2006, 12:16 AM) [snapback]351597[/snapback]</div>

<div class='quotetop'>QUOTE(jkm750 @ Nov 19 2006, 12:16 AM) [snapback]351597[/snapback]</div>

Don't drive you car until it get so low with car. It not good for any car to run on nearly empty. Full up at four bars as a habit. Then quit worrying

 

well there are other issues...

winter fuel has less power so your mpg's will drop

cold air is denser, so your mpg's will drop

cold engines in a cold environment take longer to warm up and run efficiently so your mpg's will drop

finally, your battery does not do well in temperature extremes, and cold is MUCH worse for it, so its charge capacity will be reduced and that will reduce your coasting distance.

 

I fill up often enough, I can easily find a change in how the tank is working for me. I fill up about every 3 to 4 days.

In the summer, (for me), it's very predictable. When it goes from 4 bars to 3, I'll get about 52 to 55 miles then it will go to 2 bars, I'll get 52 to 58 miles, it goes to 1 bar, it'll go about 25 miles and start blinking. I've never figured it out beyond that. If it's blinking, I'll get 10.xx gallons in and repeat the process.

Now that it's cold out, I just got decent range on bar #3 (50-55 miles), then bar #2 lasted about 20 miles (huge skew in performance) at which point I had to wonder.....

Did I really burn part of #2's gas while I was showing #3 still, or do I have a very generous #1 to burn still.

3 miles until I hop on the tollway for a 40 mile ride, I have to stop to fill up on this end rather than waiting to fill up on the other end.

What does that matter if I fill up now, or 40 miles down the road? To me, it's a lot. If I had that next 40 on the bottom end of that last tank, I'd have 40 more on this tank... maybe I get to go another day between filling up.

I'm not looking for a miles to empty. With the huge variance of mpg achieved, I can see how miles to empty could be 40 right now, and drop all the way to 5 within just a short distance. If that were happening, we'd be hammering toyota big time about the accuracy of that system.

I would love to know gallons. I fill it up and sqeeze it full to the neck, I see 10.5 on the reading for a long long time until the neck empties out and I'm at 10.4 gallons. Start the blinking thing whenever you want, but let me be confident when it says 2.2 gallons that I really have 2.2 gallons. When it says .4 gallons, I am not going to hear the motor die.

When it says .1 gallons, I should feel good that the motor is about to die.

I think they put a lot of money into the gas tank system, I just think they went down the wrong road. Redesign it to achieve all the current goals while also getting this right.

 

actually, i believe that the digital gauge does work in an "on-off" scenario when blips disappear but should simply only be used as a guideline for general impressions of how much is left in the tank.

i tracked the mileage between bars for a while and noticed

1) bars disappearing overnight

2)bars reappearing


so use it as a guideline only. iow, just like any other gauge.

now before everyone posts case histories of cars they've had in the past where they could compute to the mile how far they could go, let me say that i predict the incidences of people running out of gas (only counting people who have money to buy gas) will not change significantly with these types of fuel gauges.

 

I can't complain about the gas gauge, it wasn't that long ago that I ran out of gas in a very expensive car that had the fuel gauge fail in the interesting mode of 1/2 tank. If it had said "full" all the time or showed "empty", I might have known something was up, but at 1/2 tank, I just kept driving, for a few more days anyway... One tow bill and an hour or two of shop time to diagnose & repair, and it was good as new. I started using the odometer as my gas gauge after that, and have never quite gotten out of the habit. So, the Prius gauge is not a problem to me.

The reasons I've heard for not running down to empty in the good old days were avoid getting the water/dirt/gasoline ratio too out of whack, and in more modern days, the claim that the in-tank fuel pump is cooled by the gasoline. Both seem a bit more urban-legendish than practical advice, but I prefer to keep at least a 1/3 of tank, just in case. The only disadvantage seems to be 1) perhaps more wear and tear on fuel filler door hinges and gas cap and 2) MPG impact of carrying more weight of fuel. Number 1 seems negligible, number 2 is quantifiable, but small. Figure out weight of fuel between 1/3 and 1/8 tank, assuming you run it that low, etc. etc. I suppose if you were worried about the weight, you would fill up to 1/2 tank only, but that seems silly.

 

<_< Fron the "When to fuel..." vantage point, I consider the Prius to be like people... every one is different.

In my recently traded 2004, I had become accustomed to when to add fuel - one unblinking pip. Only twice in over 2 years did I wait until the single pip was blinking. Never ran out of fuel.

My new 2007 Touring Edition still is on its "full tank when new" fuel, so I have not yet begun to 'understand' its fuel tank characteristics.

My procedure: NEVER run out of fuel. Too many unpleasant results can occur both on the road and with the Prius' peculiarities. This also is related to my history as a light aircraft pilot.

 

Okay, that's sort of what I thought, and sounds like the same mode
I was describing over on P_T_S as "WFO mode" which means the same
thing. Definitely repeatable, and I'm not sure it's based so much
on rapidity of accelerator movement than just a really high demand
level. I think I've opened slowly and smoothly to that point in
my own playing around. What I observe about it is vacuum drops
solidly to zero, I hear a lot more intake noise, and MPG goes totally
in the toilet. If I bring my foot back v-e-r-y slowly [given the
leeway to do so] I can get back down to maybe 1200 rpm with the
vacuum still pretty much down at zero and stay in that mode for as
long as I've got road. I even managed to get on this plateau and
let the cruise-control hold it for a couple of miles once. It's
definitely a higher-power mode, but according to my scantool the
engine doesn't actually go open-loop as with most other full-throttle
scenarios. It's actually only about 45% throttle... I finally drop
off it when my foot pretty much reaches zero demand.
.
Not exactly keeping to the OP subject, but definitely worth trying
to learn more about. Useless for MPG, though.
.
_H*

 

strange thing was that I just went out to the car hit the power button once to put it in acc. mode and took the pix of the mfd. Question then what does your scantool say in Acc. mode about the WFO/WOT conditon? Is it listed or is this just an anommoly on this car?

 

erm.. it doesn't say anything in ACC mode, the ECUs have to be
powered up to at least IG-ON before they start talkin'. Unless
I'm missing something..
.
_H*

 

<div class='quotetop'>QUOTE(hobbit @ Nov 21 2006, 08:31 PM) [snapback]352881[/snapback]</div>

ok I guess what was shown is the last from the flash rom that gets saved.

 

I have run out of gas once, I believe I got 82 miles on the blink.
The repair manual does indicate the fuel pump could burn out if operated for more than 10 seconds when dry. However, the Prius would shut off the pump if the ICE is not able to start or the airbags deploy and will leave it that way until you power off and back on again to retry.
So, cars that don't cut the fuel pump in a no-start condition could blow their pump if dry, but the Prius isn't one of them.

 

I've been driving my 04 since Nov 03 and I still LOVE it. To this day, I really still only have two complaints on the car.

1. The seat is just not comfortable. I have gotten used to it as I regularly drive over 25K per year, but because of the seats, the family takes the Sienna on all vacation-like trips and I feel a little guilty at the MPG (and I miss my baby!)

2. I regularly get down to 1 flashing pip at 350 miles and even if I stretch it and wait to fill up around 400 miles, I rarely get more than 7.5 to 8.5 gallons in the car. It isn't a big deal, but it does mean that I have to fill up about once a week.

Still love the car though!!!!!

 

gee rick, bummer about your fuel capacity. almost sounds as if your bladder never fully expanded. ever have it looked at??

guess without x-rays, it would be tough to determine how expanded the bladder was. i would be tempted to try and force some extra gas in at fillup time, but again, that isnt a great idea either.

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ Nov 22 2006, 01:09 PM) [snapback]353057[/snapback]</div>

Dave,

I anally recorded all of my fill-ups and compared calculated vs. MFD MPG (look who I am talking to!) for the 1st two years and the data was very consistent and I thought about having it looked at, but I am so happy with the car, I have always hesitated to have the local Toyota folks mess with it unless I have to. I'd love to get 500 to 600 miles per tank, but it's not that big of a deal.

Rick

(P.S. It took a very strong effort of will to stop logging each fill-up but I think I am generally happier now....I think it is like being an alcoholic though...I will always be "recovering!!")

 

lol...ok... well, im a loooong way from accepting a 12 step program. in fact, i doubt that i will ever stop logging my mileage as long as i am surrounded by 25 mpg cars.

 

<div class='quotetop'>QUOTE(Frank Hudon @ Nov 19 2006, 04:34 PM) [snapback]351838[/snapback]</div>

Wow nice display! How can I get one?
Jim

 

<div class='quotetop'>QUOTE(Jim Biggs @ Dec 9 2006, 12:55 PM) [snapback]359829[/snapback]</div>

www.hybridinterfaces.ca

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ Nov 19 2006, 09:17 AM) [snapback]351717[/snapback]</div>

Dave are you going to spring for the new CAN View?

 

i want to, really really really miss the extra info. without CANVIEW, there is little data to track. i stuffed the frond end of my car with pipe foam insulation, so really curious as to how it affects my warmup time. i still have a lot of saved data from my 04 on how fast it heated up.

but not sure i want the extra display option or how it will fit. i dont know.... might go for the little portable monitor thing like you had.