SabrToothSqrl

Well, I'm sure GM has never done anything "intentionally"...

GM Changed Ignition Part Without Telling Drivers, Regulators - NBC News

But as for the gauge, I agree.

73shark

If I fill the tank and it uses 10 gallons upon a refill at the same station same pump, then it used 10 gallons no matter what the DIC says.

If you continue filling to the point of what the DIC says was used, you will eventually not have any gas in the tank.

in2pro

So far that has not been the case, every fill up for the past 5, putting in only what the DIC says was used, has put the needle at the full mark...

I suspect that if you check the DIC's gallons used at every fill up, you will not get more then 1 to 1.5 gallons more in the tank at fill up...

I will continue to put in only what is used and monitor the needle position and make note at the first sign of any variance...

73shark

Not sure how to account for using a measured (by the pump which is certified) amount that is almost always more than the DIC.

I can compare the total amount of fuel put in the tank over 30K miles and it is more than the total amount from the DIC.

in2pro

You are correct and I understand the part of the pump being a known certified value of volume ... as for how the vehicle calculates what is used I can't say, could be the fuel pump fluid level float for all I know and I get the part of potentially running out of gas if I did not ever look at the fuel gauge and only went by the DIC's gallons used...
However, so far I have been able to put in what the DIC says I have used and so far have always come up with a full tank...
Is hand calculation accurate? yes, as long as you always go by those numbers and the vehicles trip...
As long as I always get a full reading on the gauge at fill up using only the DIC's value, then the DIC's calculation should also be considered accurate... (guess this would prove out also if you are always within a mile or less of mpg between the two)

I am trying to be devil's advocate for the DIC's display of MPG...

a55bruce

I've tracked the reported vs. actual gallons used for ~8000 miles, and I've found that the tank to tank fill-up accuracy depends on the tilt of the filling station. As to overall accuracy my spreadsheet shows 564 gallons bought vs. 554 gallons as shown on the DIC. This is on a 2011 Tahoe LT
1.7% error ain't too bad. YMMV

Dave01

I think you're either interested in mpg or your not. Sabr, I get it that you don't care, but I find it interesting to track in various vehicles, how my driving and where I drive affects it, etc. Just another aspect of engines/fuel/vehicles that I enjoy.


I've never found a DIC that was accurate, so don't bother with them, always hand calculate. And, if you do that hand calc over 2 or 3 tanks combined you really get accurate figures because the slight fill level difference goes away.


In2pro, interesting that you've figured that out, I guess it never occurred to me. Still not sure I'd ever trust it though! Thanks for posting the info.

73shark

Don't have my figures w/ me but the mpg error runs in the neighborhood of 5% on mine.

in2pro

a55bruce & Dave01
Thanks for the feed back, a55bruce that was the jist of what I was getting at... the DIC is accurate enough, just have to make sure to compare apples to apples...

If you are not an MPG tracker then no big deal but the DIC should be used as a monitor for fuel economy... if you see a significant drop in the MPG on the DIC, you might want to consider looking into a possible servicing issue...after all that is what stirred my interest in the DIC Vs hand calc... I did a tune up and saw a mild increase in MPG....

Dave01

I'm seeing 5-7% less mpg on actual vs. DIC. But, to the point in2pro is making I'm one of those people that probably fills too full, tend to top off the tank.


I agree, DIC can be a good week to week indicator of whether something has changed drastically with mileage.