DIC Gas mileage?
Thread Starter
Pro
Joined: Feb 2012
Posts: 521
Likes: 0
From: Wichita KS
DIC Gas mileage?
This may have already been done before but let's get fresh numbers. Has anyone ever compared their actual gas mileage to the DIC indicator to judge it's accuracy? I'd like to hear what you found.
Thread Starter
Pro
Joined: Feb 2012
Posts: 521
Likes: 0
From: Wichita KS
mine is consistently within 0.1mpg of what I calculate based on gas pump gallons and odeometer miles. I reset mine every fill up so I'm not getting a cumulative mileage which might be considerably off especially if my right foot was unusually heavy the last tank fill up.
Pro
Joined: Apr 2011
Posts: 568
Likes: 2
From: Dayton, Oregon
Oldtimer
Mine was about 2 MPG higher than actual when I first got it 9 months ago. It's within 0.1 of paper and pencil figures now, I hear it takes some time for it to get used to your driving style. Average town/country is 24 MPG for me, I'm seldom on a freeway. I don't baby it but i don't beat on it either, it's common for me to pull it out of OD in some twisties.
BTW, I reset the trip odometer at each fillup too.
BTW, I reset the trip odometer at each fillup too.
Last edited by FormerlyFiero; Apr 6, 2012 at 01:11 PM. Reason: Added trip odo
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
My 99 FRC is very close between the DIC and the actual mpg at fill ups.
My 99 6 speed hatchback the DIC shows about 2 or 3 mpg more than I actually get at fill ups. It might be because I have some mods and a tune on this car.
I also heard that there is a correction factor available if you have your car tuned, but I have not done that yet.
Just FYI, my C4's were very close (checked on two 94 6 speeds, and one 88 auto )
My 99 6 speed hatchback the DIC shows about 2 or 3 mpg more than I actually get at fill ups. It might be because I have some mods and a tune on this car.
I also heard that there is a correction factor available if you have your car tuned, but I have not done that yet.
Just FYI, my C4's were very close (checked on two 94 6 speeds, and one 88 auto )
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Racer
Joined: Oct 2010
Posts: 278
Likes: 1
From: Ware Shoals SC
Mine on the '99 adds about 1 mile (just to make me feel beeter because our love is mutual)
I can't remember if my old '91 even had a mpg display but I think it did.
I'm glad the '77 doesn't. I don't want to know what it says. It just hurts too bad to think about it.
I can't remember if my old '91 even had a mpg display but I think it did.
I'm glad the '77 doesn't. I don't want to know what it says. It just hurts too bad to think about it.
Melting Slicks
Joined: Oct 2007
Posts: 2,798
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From: It's true money can't buy happiness, but it is more comfortable crying in a Corvette than on a bicyc
St. Jude Donor '13
Mines off 10% to the plus side. If the dic reports 27 its really 25 point something.
Instructor
Joined: Aug 2010
Posts: 186
Likes: 0
From: Las Vegas NV
Anyone know how they're doing the calculation? Obviously they get how fast you are going from the computer....but how much fuel you are using must be done by what the computer is telling the injectors to be using?
In this case, if your numbers are off, perhaps injectors aren't performing correctly? Just a thought.
In this case, if your numbers are off, perhaps injectors aren't performing correctly? Just a thought.
Racer
Joined: Feb 2004
Posts: 359
Likes: 7
From: St. Paul MN
Anyone know how they're doing the calculation? Obviously they get how fast you are going from the computer....but how much fuel you are using must be done by what the computer is telling the injectors to be using?
In this case, if your numbers are off, perhaps injectors aren't performing correctly? Just a thought.
In this case, if your numbers are off, perhaps injectors aren't performing correctly? Just a thought.
Fuel injector swaps often get flaky DIC MPG results if the tune data isn't right on, so I am going to guess the PCM calculates the amount of fuel used based on the duration the fuel injectors are commanded open. Or some derivative of that value.
Then total mileage is probably summed by capturing the momentary MPH at a set interval and calculating distance travelled between intervals (55mph = 80 feet/sec). Wheel size or diff changes would skew your speedometer mph which would also throw off total miles travelled as well as MPG. But those can also be adjusted by tuners.
Both Vettes I've owned with stock injectors & stock tune have been slightly optimistic by 1mpg or so. That tells me the injectors are flowing just a smidge more than the computer realizes.
Todd
Race Director
Joined: May 2010
Posts: 16,574
Likes: 13
From: Winfield IN
