Accuracy of D.I.C Avg Economy

Jansen · February 15, 2005

My Avg Economy for MPG is off by .5mpg. I've checked it 3 or 4 times now and it is consistently off by a little. I've also noticed that the gallons used is always off by a half gallon as well. If it says I used 18 gallons, I really used 18.5 and if It said I had 18mpg i really had 17.5mpg. My outside temp gauge is off a little as well. How is everyone elses?

Thanks

Jansen

lrymal · February 15, 2005

...My outside temp gauge is off a little as well. How is everyone elses?
Jansen

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I'd say your numbers are within guide. The ambient temperature guage is rated for only 4 degrees accuracy, including third market guages. One company's is rated at only 5 degrees. I have no idea why these things are so far off, especially the temperature guage, which has been a sore point for years for me.

And for decades, the fuel gauge has been a gripe point for me. I can guarantee that your half full reading is not half full, no matter what make vehicle.

WyRam · February 15, 2005

...My outside temp gauge is off a little as well. How is everyone elses?
Jansen

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I'd say your numbers are within guide. The ambient temperature guage is rated for only 4 degrees accuracy, including third market guages. One company's is rated at only 5 degrees. I have no idea why these things are so far off, especially the temperature guage, which has been a sore point for years for me.

And for decades, the fuel gauge has been a gripe point for me. I can guarantee that your half full reading is not half full, no matter what make vehicle.

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My fuel is off at 1/2,my DIC is of 1/2 mpg and my gallons used is off 1 gallon.My Ram was almost perfect at 1/2......my 02 Durango was a bunch off at 1/2 tank.

biochemist · February 15, 2005

Hey, I would say my MPG is off by about .5 mpg, sometimes it is right on though. My used gallons is off by ~.5-1 gallon at full fill up...This is dependent on if you are on a slight incline when you fill up, or how full you decide to make the tank etc...but overall the system is quite accurate IMO, within 3-5%...I do not know how it works and calculates these numbers...does anyone else? As far as temp, mine is always within a degree or two...well, I guess, all I have to go by is the radio or a bank sign....but again, pretty accurate. Later,

1500CCZ71 · February 15, 2005

I would say that my trip computer is off 0.5 - 1.0 mpg and 0.5 - 1 gal. used each tank. However, the outside temperature reading seems to be very accurate.

jeb · February 15, 2005

Mine is in line with everyone esle's. It's much more accurate than the built in trip computer that was in my 03 Ford Excursion Lmtd. That was always 1-3mpg off.

jaslo · February 15, 2005

Mine is of 1/2 mpg, and always uses more fuel than what it says.

Scyry · February 15, 2005

My truck can run out of gas at an 1/8th of a tan showing or when I have driven 20 miles past the needle not moving (was lost in the CO mountains). I never let my truck get below 1/4 full anymore beause i don't know when it actually will run out of gas. The two times it ran out at 1/8 a tank the "low fuel light" hadn't come on yet. Dealer just shrugged it off and said the gauges are netoriously off.

navyblue1500crew · February 15, 2005

I've gotten 4 sets of data on my 05' CC (I check all my cars at every fill). The worst the indicated mpg calculation has been off is by 0.5 mpg (high, of course--they want you to believe...); the best by less than 0.1. Pretty decent accuracy.

After 1366 mainly highway miles, the 5.3 (with a 3.73 rear) is averaging 16.67 actual mpg, and with what I've had to pay for fuel, that's worked out to almost 10.4 cents per mile for fuel.

I'm not sure why whatever car or truck (always GM) I've had with outside temperature indication always reads higher than actual...do they want us to believe it's warmer out there?

Okay, enough smileys...

toneman · February 15, 2005

I believe there is a TSB related to the fuel economy readings on the DIC, although I don't know if the TSB describes a fix or it it's just saying that "yeah, it's not accurate but it's within specs" or something like that.

caremd99 · February 15, 2005

Mine is also reading .5mpg optimistic. However, the reading in my Maxima always reads 4mpg optimistic. So at least GM can crunch the numbers better than the competition.

dewfpo · February 15, 2005

My coolant temp gauge even reads 1 tick above 160 when the engine is stone cold so I don't put much credence in any of the readings I get from the gauges. Their there for a guide and that's about all you can use them for. That's why Ford's don't have numbers. These are low bid gauges and are not designed to be accurate by design. It's just a illusion.

DEWFPO

tryn2lrn · February 16, 2005

I tested the temperature on the mirror and it is very accurate (although slightly slow to respond) to + or - 1 degree. I installed the mirror and sensor myself and wanted to verify the job. I brought home the thermocouple meter and the mirror was always within 1 degree of the meter. Good enough for me

P.s. This is only valid while moving, when sitting still they did vary by a few degrees for some reason.

biochemist · February 16, 2005

I tested the temperature on the mirror and it is very accurate (although slightly slow to respond) to + or - 1 degree. I installed the mirror and sensor myself and wanted to verify the job. I brought home the thermocouple meter and the mirror was always within 1 degree of the meter. Good enough for me

P.s. This is only valid while moving, when sitting still they did vary by a few degrees for some reason.

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It is because the sensor is close to the motor (I think it is in the front grill area...right??)...the air warms up...temp goes up...need to be moving for it to be accurate...later

MrQuadrasteer · February 16, 2005

I checked mine a half-dozen times when it was new and it always was NO MORE than .1mpg off, often dead on.

I've run mine down to w/i 18miles left on RANGE, long after the yellow light came on.... Not something I do often, btw !!!

And my temp is always w/i 1* of what the radio claims. I don't trust bank temps- I've seen them say some weird temps...

Overall, I think the gauges and the DIC are FAR superior to what was stock just a few years ago.

Now, I need to recheck to see what effect, if any, the tune has had on the readings. I know I'm seeing some sweet increases, in excess of 2mpg at times ...