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Old 08-06-2006, 12:54 PM
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mglobe
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Default Remaining range

In the interest of all Rennlist members, I've tested the accuracy of the remaining range message (actually, I just didn't get to the gas station quick enough). At any rate, with my gauge saying I had 14 miles to go, when I accelerated, the engine died, then came back to life. Tried it again, and it did the same thing. I of course immediately drove into the next (and most expensive in the area) gas station, and filled up. The car's behavior tells me that the outlet for the gas tank is in the front of the tank, and that acceleration sloshes the ramaining gas to the back, thus starving the engine. I was a little surprised though when the engine sputtered like that, as all of my previous vehicles would run right down (and past) the zero miles left with no problem (not that I test it out all that often, but it has happened).

So... a warning to anyone who's not yet driven the car to that low of a fuel reading. Anyone else experienced this?
Old 08-06-2006, 02:17 PM
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cr2000
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Thanks for the post. In general running a car that low is simply not a good idea, but I've done it before. I hit 48 miles to go this weekend and wondered just how accurate the Porsche guage is. No more, I'll make sure to keep it above 75miles.
Old 08-06-2006, 02:42 PM
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robbonds
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ive taken mine down to about 8 miles with no problems
Old 08-06-2006, 03:03 PM
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ChipAZ
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The low fuel light comes on at around 50 miles to go, with about 2 gallons left in the tank. I've found that range estimators in other cars are usually way off. Had a Mercedes once that said there was 500 miles to go every time I filled up and rarely made it to 400.

Porsche seems to be the most accurate yet.
Old 08-07-2006, 08:49 PM
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Thanks for the real life numbers. With the 997s and the 996s in particular, Porsche strongly recommends that you not run them that close to empty. (Many years ago I ran my 914-4 down to empty, covering some 512 miles (Roseburg, Oregon to King City, Calif) with a consumption of 15.4 gallons of petrol. I apparently still had a gallon sloshing around in there somewhere!) 34 mpg! Best ever and never possible again!
Old 08-07-2006, 09:55 PM
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I think that the remaining range is pretty accurate with regards to what you have left in the tank. There is no 'bonus' gallon for safty. I am able to verify this by subtracting the filled up amount from tank capacity and then verifiing the amount based on MPG. So if it says 10 miles left, you likely have less than half a gallon.
Old 08-07-2006, 10:35 PM
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Originally Posted by Deven
I think that the remaining range is pretty accurate with regards to what you have left in the tank. There is no 'bonus' gallon for safty. I am able to verify this by subtracting the filled up amount from tank capacity and then verifiing the amount based on MPG. So if it says 10 miles left, you likely have less than half a gallon.
I can pretty well confirm that from my ahem experiment. In retrospect, it was pretty dumb to run it down that low. Hopefully by posting I can prevent others from feeling the need to test this particular limit of the car.
Old 08-08-2006, 02:43 AM
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Edgy01
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Mike,--is that the Midnight Blue? Interior?

Looks nice.
Old 08-08-2006, 05:29 AM
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Marsellus Wallace
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Originally Posted by mglobe
In the interest of all Rennlist members, I've tested the accuracy of the remaining range message (actually, I just didn't get to the gas station quick enough). At any rate, with my gauge saying I had 14 miles to go, when I accelerated, the engine died, then came back to life. Tried it again, and it did the same thing. I of course immediately drove into the next (and most expensive in the area) gas station, and filled up. The car's behavior tells me that the outlet for the gas tank is in the front of the tank, and that acceleration sloshes the ramaining gas to the back, thus starving the engine. I was a little surprised though when the engine sputtered like that, as all of my previous vehicles would run right down (and past) the zero miles left with no problem (not that I test it out all that often, but it has happened).

So... a warning to anyone who's not yet driven the car to that low of a fuel reading. Anyone else experienced this?
Be careful letting the car run out of gas-you risk damaging the catalytic convertor/s on the car.
Old 08-08-2006, 07:38 AM
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mglobe
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Originally Posted by Edgy01
Mike,--is that the Midnight Blue? Interior?

Looks nice.
Yes Midnight Blue on Stone Grey. In the right light, and when clean, a great color. Thanks!
Old 08-08-2006, 08:05 AM
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Ronnie
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I have taken my remaining range down to "---" without any problems. Not by choice cause I know its not meant to be good for the car.
Old 08-08-2006, 10:26 AM
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I think it's more of a wives tale that it wouldn't be good for the car to run it low. Of course, there's the risk of running out which is more of a fact than a wive's tale but in terms of bad for the engine it shouldn't be. I find it hard to fill up before 50 miles left when my tank only lasts 200 miles.
Old 08-08-2006, 10:36 AM
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Ah my favorite way to egg the wife. The remaining miles indicator. It's based on engine speed so 50miles can turn into 10 miles in 2 secs. That said, I've never had my 997 down to more than 20miles at cruise speed. The older 964 trip computer wasn't very accurate.
The most accurate was my NSX and my old E39 M5. I did the calculations based on miles left and mpg readings and they were spot on.
Old 08-08-2006, 11:16 AM
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gpjli2
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Originally Posted by stom_m3
I think it's more of a wives tale that it wouldn't be good for the car to run it low. Of course, there's the risk of running out which is more of a fact than a wive's tale but in terms of bad for the engine it shouldn't be. I find it hard to fill up before 50 miles left when my tank only lasts 200 miles.
Sediment from bottom of tank is the problem here. It is a real concern.
Old 08-08-2006, 11:38 AM
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Originally Posted by gpjli2
Sediment from bottom of tank is the problem here. It is a real concern.
If that's the case, than why would it only be a concern when the tank was empty? The pump sucks the fuel from the bottom of the tank. So unless the sediment your talking about floats??

Today's fuels are much cleaner than in the past. The need to worry about such things is old tale. Not to mention you have a fuel filter that will filter all of the small particles anyway. And this is the same for the water in the tank tale as well. Water being heavier than gas will get sucked up first.


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