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MPG readout accuracy.
Posted: Sun Feb 11, 2007 7:54 pm
by RacerZX
Can somebody please do a test and see how closely the computer's MPG display matches the real life data when you fill up? I.E. keep track of milage from fill up to fill up and divide the miles by the gallons you put in to see how closely that resulting number and the MPG display match?
I'm trying to figure out how much if at all my supercharger is skewing the MPG numbers, since fuel flow to that 7th injector isn't going to be metered by the ECU...
Posted: Mon Feb 12, 2007 12:17 am
by mtbpath
I am within .20.
my data is .20 higher vs the computer.
Re: MPG readout accuracy.
Posted: Mon Feb 12, 2007 2:38 pm
by rlh2005
Hope this helps
Code: Select all
Date Miles Gallons MPG TripCmp price
8/7 0.0 12.555 0.0 UNK 2.799
8/12 145.1 9.555 15.2 14.9 2.779
8/15 380.0 20.767 18.3 17.2 2.749
8/25 268.5 18.684 14.4 16.0 2.579
8/27 261.6 15.810 16.5 16.1 2.569
9/1 169.4 11.257 15.0 15.8 2.489
9/3 387.3 19.827 19.5 16.6 2.589
9/10 333.5 20.868 16.0 16.3 2.359
9/18 300.0 18.032 16.6 16.4 2.119
9/23 179.3 9.447 19.0 UNK 1.979
9/26 365.9 19.919 18.4 17.0 1.939
10/1 118.1 7.738 15.3 16.8 1.919
10/2 284.2 14.953 19.0 17.2 1.8999
10/19 332.5 21.938 15.2 UNK 1.989
10/25 272.6 16.599 16.4 UNK 1.939
10/27 81.3 5.701 14.3 15.1 2.019
10/28 280.1 15.262 18.4 17.3 1.979
11/8 260.4 17.665 14.7 16.4 1.979
11/16 226.0 14.747 15.3 16.0 2.039
11/18 149.7 8.296 18.0 16.4 2.039
11/20 332.6 17.747 18.7 18.8 2.029
11/25 82.8 6.189 13.4 17.8 2.059
11/26 353.6 17.070 20.7 19.0 2.039
12/1 235.3 14.553 16.2 18.2 2.139
12/3 344.5 18.820 18.3 18.3 2.179
12/13 270.0 18.985 14.2 17.6 2.319
12/18 304.3 17.822 17.1 17.4 2.359
12/24 249.6 16.772 14.9 16.9 2.359
12/29 176.2 11.270 15.6 16.7 2.359
12/31 344.2 17.735 19.4 17.1 2.499
1/4 315.5 18.892 16.7 17.0 2.299
1/6 370.9 18.063 20.5 17.8 2.319
1/13 288.5 17.129 16.8 17.6 2.339
1/21 267.7 17.572 15.2 17.1 2.219
1/26 90.0 7.232 12.4 16.7 2.159
1/27 256.9 14.137 18.2 16.9 2.159
1/30 345.7 17.508 19.7 17.3 2.149
2/6 248.3 17.073 14.5 16.8 2.199
The MPG column is my miles drive / gallon fuel.
The TripCmp column is the trip computer's MPG calculation. Note, I do not reset the trip computer's MPG at refuelings. I'm trying to use it as a lifetime MPG. Granted, it was reset when the dealer repaired/replaced the fuel gauge sending unit.
Thank goodness, I have a PDA/Smartphone. I just enter the data in my cell phone at each fill-up.
Posted: Mon Feb 12, 2007 3:05 pm
by RacerZX
That doesn't help at all to know you have cheap gas! I pay almost $3/gallon for premium over here...
Posted: Mon Feb 12, 2007 5:26 pm
by jerry6
well 91 octane is 96 cents to $1.26 a litre here !! i wish i paid $3.00
Posted: Tue Feb 13, 2007 11:51 am
by rlh2005
RacerZX wrote:That doesn't help at all to know you have cheap gas!
If it's any consolation, the prices before 12/13 are 87 octane.
Posted: Wed Feb 14, 2007 7:56 am
by boogyman
Hey Racer, the computer is going to tell the average of the last little bit you traveled. So if you were putting along just before you got gas the computer will show something totally different than what was going on the rest of the time. So basically the computer is a useless display for MPG.
Posted: Wed Feb 14, 2007 8:48 am
by RacerZX
Hm, that's actually not my understanding. The MPG readout is the average since last reset, it's not a real-time display.
Posted: Thu Feb 15, 2007 3:51 pm
by phantom2
Racer,I think your interpretation of the "mpg" readout is correct
Posted: Thu Feb 15, 2007 4:48 pm
by Middle Man
mtbpath wrote:I am within .20.
my data is .20 higher vs the computer.
That's quite similar to what I have experienced.
Posted: Wed Apr 25, 2007 9:55 pm
by blink32
Figger I'll throw my 2cents in.
06 Path LE, Nismo intake, OME lift, 285/70R17 AT's @ 46psi, Yakima rack removed
CT to NJ @ 71-73 avg corrected MPH
Digi showed 16.9mpg over 207.8 mi trip
Actual was 17mpg over a corrected 222.4 mi trip
NJ to CT @ 65-66 avg corrected MPH
Digi showed 18.3 over 216.3 mi trip
Actual was 20.5mpg over a corrected 231.4 mi trip
Not sure why it was off so much going slower to CT but I double checked my numbers and set the timers/odo the same way both directions. And didn't do any calculations until I was home with all the numbers on my notes sheet. I posted the corrected numbers because my tires cause a 7% error on the speedo (assuming the stock size of 265/65R17 are 100% accurate). I'm going to redo the test probably next month when I go back up for the sake of consistency.
Posted: Thu Apr 26, 2007 10:19 am
by G35TR
I was curious about this myself, so I've been testing the mpg guage on the current tank (which is just about empty). I'll let you know my results after i fill up, which will probably be tomorrow.
Also, anyone else notice the HUGE difference between the first half of the tank, and the second half (according to the guage)?!?!
I got got about 190 miles out of the 1st half. I couldn't believe it. I thought to myself, that mpg guage is way off if I'm on par for almost 400 miles per tank!! Then the next thing I know, 100 miles later, my tank if almost empty. And there driving was the same throughout the entire tank.
Is it like this on all the Pathfinders??
Posted: Thu Apr 26, 2007 10:25 am
by RacerZX
Yeah, I've seen the same thing. Last 1/3rd a tank is only good for about 75-100 miles!
-c
Posted: Thu Apr 26, 2007 11:13 am
by mtbpath
RacerZX wrote:Yeah, I've seen the same thing. Last 1/3rd a tank is only good for about 75-100 miles!
-c
same, here. first half of tank does not equal to last half of tank.
the last half drops faster.
I average 200 on my first half but only get 100-125 on the last half.
it gives you a false sense to rely on the gauge.
Posted: Thu Apr 26, 2007 11:52 am
by blink32
I don't know if you guys have seen the threads on the Australian boards but they are complaining of the same thing in the Gasoline models. Gauge and digi will read empty but they have something like 20 liters left (over 5 gals). I see the same issue. Apparently they are getting fixes for this over there. The diesels are fine though.
I see the same thing, last time I hit E and the digi gauge went to XX miles left I just kept on rolling for a solid 50 miles then filled up and still had something like a gallon & 1/2 left in the tank. Nissan either built in some rediculous safety margin or there is a problem with the in tank gauge.