MPG updates

[brendon]

I ran a year before I got the sc programmer and it was about a 2MPG gain after the correction. That was running the 265's

I could be wrong, but I don't think running with the tire correction changes real world MPG, just the way you (or your EVIC) figure it out.

If you are running uncorrected, the car travels farther than what the odo is reporting, for example it may report a trip of 200 miles. Do the correction and now the exact same trip will show on the odo as 250 miles. Say you used 20 gallons on each trip; according to the math the first trip you got 10mpg, but on the second trip you got 12.5mpg. Real world this trip distance as measured by a survey crew could be 230 miles giving a real MPG of 11.5 for both trips. The trip distance and fuel usage did not change, just the factors used to figure out the mileage.

Now, if the computer uses different cal factors for tire size to alter the way the Jeep puts the power to the road, then all bets are off...

[Sal-XK]

I could be wrong, but I don't think running with the tire correction changes real world MPG, just the way you (or your EVIC) figure it out.

If you are running uncorrected, the car travels farther than what the odo is reporting, for example it may report a trip of 200 miles. Do the correction and now the exact same trip will show on the odo as 250 miles. Say you used 20 gallons on each trip; according to the math the first trip you got 10mpg, but on the second trip you got 12.5mpg. Real world this trip distance as measured by a survey crew could be 230 miles giving a real MPG of 11.5 for both trips. The trip distance and fuel usage did not change, just the factors used to figure out the mileage.

Now, if the computer uses different cal factors for tire size to alter the way the Jeep puts the power to the road, then all bets are off...

You went over board on that man LOL real word mileage never changes. I was and was assuming everyone else was just reporting what the computer calculated which is off by 10% uncorrected. Now I did take the reported mileage and divide by gallons used then corrected for the error to get my actual mileage. I wasn't saying that I actually gained 2MPG real results by correcting but more that's the difference in the tire size error you get. Just pretty much telling the guy with the uncorrected speedo to add about 2 to his reported MPG so he had an idea of his actual MPG.

[Core XK]

After my lift and tires im at 12.9 to 13.2 according to my evic. I have a light foot and was getting 13.5 to 14 prior (city driving). A lift and tires will get you less mpg if im not mistaken ;p?

I stopped looking at my evic because I just dont.care anymore LOL

[06JeepXKHEMI]

Im at 12.3-12.5 with a lead foot and the sounds of the HEMI with the intake and exhaust is orgasmic!!! Lift, tires, added weight from skids will all affect mpg, but as long as its not 9.6 like I was getting before Im good with it

[Core XK]

lol Yeah 9.6 is pretty bad

[Sal-XK]

I'm at 15.9 right now

[06JeepXKHEMI]

After driving to gym/lunch, Im down to 12.2 cause its nice and cool out, so I was stretching the legs on her a bit!!! Interested in how the headers and possibly high flow cats will affect this... honestly I wont care!!!

[brendon]

No worries Sal. I hope you didn't take it as I was picking on you. Your reply I quoted just happened to be the most straight forward as a demonstration of how this COULD be misleading.

I don't want people to think that they are actually getting better mileage because their evic tells them so after a calibration for tire size. Unless of course that makes them feel better about our 'terrible' mileage in these trucks in the first place.

Anywho..
According to fuelly.com, I am averaging 11.5mpg. This is using trip miles that the jeep is reporting; the dealer supposedly calibrated for my larger tires 4 years ago. I have checked out the odo compared to my GPS and it is pretty close. I have noticed that when my speedometer reports 40mph, I am actually going about 40mph; unlike most cars with stock size wheels and tires where the speedo (and odo) report a little higher than actual.

[Sal-XK]

Nope no worries here man I hope people know I was just quoting the error pretty much and how much it was off.

[superacerc]

I'm getting about 15.5 hwy(65mph) now 14 mixed and 11-12ish city with the 91oct tune from superchips. I'm pretty happy with that. Bet I could be 16 something hwy without my rack on top.