Stupid gas pumps (calculating mileage)

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Stupid gas pumps (calculating mileage)

June 22, 2007, 11:18:18 PM

I recently had my PT in for service at the dealer (was nicely dying on the side of the road with some unintelligible code

). They replaced the crank sensor, but apparenlty they also re-flashed the ECU while they were at it (not mentioned anywhere). I found out that the ECU was reflashed because my mileage went from 24.4MPG to 26.5 MPG - very nice surprise. OK, enough history.

So now I am obcessively checking mileage to make sure this isn't a fluke. 26.5 for several tanks. Three fillups ago I went to fill up and my favorite pump was taken. Thing took more gas that usualy and viola!, my mileage was 24.4 MPG. Same thing next time I went in - someone was at my pump! This time it was 25.77 MPG which was OK but still worrying. This time I hit 300 miles at the 1/4 tank mark (new record). My favorite pump was open and this time I got 29 MPG! Guess what the average of those three tanks was? 26.4 MPG!

Moral of this post that just wasted 5 minutes of your life?

1) always use the same pump
2) average several tanks before quoting mileage numbers :D

:hick:

Stupid gas pumps (calculating mileage)

Reply #1 – June 23, 2007, 12:06:57 AM

Or... just have a trip computer :)

Stupid gas pumps (calculating mileage)

Reply #2 – June 23, 2007, 02:31:46 PM

Lots of gas pumps aren't calibrated well. I've put 26 gallons in my 19gal tank before. :wtf:

Stupid gas pumps (calculating mileage)

Reply #3 – June 23, 2007, 05:51:18 PM

Quote from: stuntmannick;156426

Lots of gas pumps aren't calibrated well. I've put 26 gallons in my 19gal tank before. :wtf:

Did you know that in Iowa there is no real enforcement of pump calibration? They have to bring in people from another state just to inspect things, so how often do you think that happens?

Stupid gas pumps (calculating mileage)

Reply #4 – June 23, 2007, 05:55:24 PM

Quote from: bhazard;156374

Or... just have a trip computer :)

yeah, but my tripminder lies to me, it shows 22 when i am only getting 19.5..... hmmm

Stupid gas pumps (calculating mileage)

Reply #5 – June 23, 2007, 07:25:14 PM

Mine lies too. Always about 5-10% high.

Stupid gas pumps (calculating mileage)

Reply #6 – June 23, 2007, 07:47:13 PM

Were being ripped off all the time,Aint shiznit gunna happen,
Unless we all quit drivin.

Stupid gas pumps (calculating mileage)

Reply #7 – June 23, 2007, 10:40:48 PM

I was wondering if I was getting ripped off too, but the 29 MPG on the last tank (at my regular pump) verified for me that the issue is related to the vapor sensor shutoff being calibrated differently from one pump to the next making it nearly impossible to check mileage unless you go back the the same pump every time. One pump at the same station was putting in an extra gallon than the other before the vapor sensor shut-off triggered.

Stupid gas pumps (calculating mileage)

Reply #8 – June 23, 2007, 11:32:42 PM

Wow.
I always thought those pumps, like many things, were strictly monitored and calibrated. Not once has the thought passed through my head that they could be inaccurate.
Well, I'll remember that for the future. I remember one trip I took in the '96 about two summers ago. According to my numbers, I got 30 mpg at 70 mph. I guess it was too good to be true, as I've never seen the car return that kind of mileage since then.

Stupid gas pumps (calculating mileage)

Reply #9 – June 24, 2007, 08:19:52 AM

Wierd indeed... having worked at a gas station for a couple years, I always heard that the pumps were calibrated twice a year to prevent such inaccuracies.

Stupid gas pumps (calculating mileage)

Reply #10 – June 24, 2007, 03:58:20 PM

Quote from: amooset;156446

Did you know that in Iowa there is no real enforcement of pump calibration? They have to bring in people from another state just to inspect things, so how often do you think that happens?

That's crazy, here in AZ they have these big ass stickers right on them that say "This pump meets the strict rules and requirements of the Arizona Dept of Weights and Measures" Then has all the little year stickers under it from the previous inspections. I guess I'll just make sure I start going to pumps with the most recent stickers though.

Stupid gas pumps (calculating mileage)

Reply #11 – June 24, 2007, 11:57:00 PM

Around here it works like a license renewal system, just pay for the new stickers and you get them... No inspection necessary. It's a load of B/S.

Stupid gas pumps (calculating mileage)

Reply #12 – June 25, 2007, 12:47:34 AM

Every now and again I'll see this big truck at gas stations.. A big calibrating machine, come to think of it I only see that truck at Speedways. So yeah buy gas at Speedway.

I did a little experiment once, I got gas at Speedway and then the next tank at Citgo.. Every car I did this with the car would run worse off the Citgo.

Stupid gas pumps (calculating mileage)

Reply #13 – June 25, 2007, 09:31:54 AM

I think I verified that the pumps were calibrated correctly based on my average mileage over the three tankfuls being the same as usual; it's just that the automatic shut-off mechanisms were different between the pumps. So, one pump would let me squeeze 1 gallon more into the tank versus the other - thus messing up my mileage calculations. The calibration stickers on the pumps were up-to-date - I checked.