Ok, someone explain this to me (MPG)

[DKS]

Damn, I'm getting 26+ on a trip in my car with a 93 octane Brenspeed tune, 3.55 gears, and 27.72" rear tires.

Getting ready to go to 28.31" tires and 4.10s in a few days. Hope it don't kill the MPGs that bad, lol

Not that I bought a Mustang for a Gas Saver anyway, but it's nice to get 26MPG with 300HP

The problem with the pump-click-off method is you are assuming the tank is full each time when the pump clicks off. Different pumps may provide different levels of fill. The tank is never truly full (ie fuel spilling out the filler) when the pump clicks off, and you can usually add more by squeezing the pump lever some more.


That is why i use the same gas station and the same pump. That way the car is parked at the same angle. The pump shuts off when the gas hits the nossle air tube, or vapor vac

And ^^^ this

 

[kenneth]

Wish mine was right, over 500 rwhp and would be getting over 33 mpg.

 

[RedMustang]

Let's agree to disagree about agreeing to disagree.

 

[JeremyH]

I hate to say this, but this is the first time, i disagree with Lightblade. I installed 4:10's and a 28 1/2 tall tire, added that info to my tune to adjust the speed-o. And my message center MPG is right on, and i confrim it the old school way.

One of the things used in calculation by the car computer is "pulses per gallon" It's a parameter available in prp. Once it has been calibrated it's damn close, like within .2 for me.

The way I understand it is it doesnt matter if you adjust revs per mile or gear ratio to fix the speedo. Like Bruce said you have to go in and calibrate the parameter. Other wise it will be off, not saying you cant calibrate it but 9 out of 10 times guys with different gears, tires, fuel mods, it it will be off. This is nothing new.

 

[gil_t2]

With my 4:10's and 28.5 tire, on the highway not exceeding 2200 rpm i am getting 28.6 over an 80 mile trip to moms. That was with my 5sp. I just in stalled a 6sp with .74 5th, and .50 6th hope to see 30mpg next.

 

[JeremyH]

The problem with the pump-click-off method is you are assuming the tank is full each time when the pump clicks off. Different pumps may provide different levels of fill. The tank is never truly full (ie fuel spilling out the filler) when the pump clicks off, and you can usually add more by squeezing the pump lever some more.

What you really need to know is exactly how much fuel was actually consumed over your trip mileage, and that is difficult to do using a refill measurement method, unless you fill the tank repeatedly to the point when the fuel starts to spill out.

The PCM has a PID called FLI, or Fuel Level Indicator. This PID reports the percentage of fuel remaining in the tank to two decimal places, ie 73.28%. This fuel level accuracy combined with the PCM's knowledge of exactly how many miles were traveled should provide for a more accurate calculation than trying to calculate it manually. Can anyone explain why it wouldn't?

Its not hard at all and very accurate to do the fill method. If you let the nozzle auto shut off your talking maybe .001 gallons differnce each time lol.

Ensure speedo is calibrated for your setup. Fill tank till the auto clicks off. reset trip meter to zero. Drive. Fill to the auto click off again. the gas pumps read you put 3.68 gallons in the car to fill it. The trip meter says you went 32.2 miles.

32.2 miles / 3.68 gallons = 8.75 mpg

 

[Noclutch]

Since I installed the lt's and o/r x pipe my milage has gone down from 18mph to 15.6 mph. I just can't help myself.....now what?

 

[gil_t2]

Since I installed the lt's and o/r x pipe my milage has gone down from 18mph to 15.6 mph. I just can't help myself.....now what?

U like the sound to much, keep your foot out of it. LOL

 

[God]

[ That is why i use the same gas station and the same pump. That way the car is parked at the same angle. The pump shuts off when the gas hits the nossle air tube, or vapor vac

The fuel nozzle shut off valve is not intended to be a measuring device. Can you guarantee your pump will click off within 0.01% of 16 gallons each time, because that is what you are competing against with the computer calculation.

From page 57 of the Owner's Manual:

Average fuel economy (AFE)​

Select this function from the INFO
menu to display your average fuel
economy in miles/gallon or liters/
100 km.
If you calculate your average fuel
economy by dividing miles traveled
by gallons of fuel used (liters of fuel used by 100 kilometers traveled),
your figure may be different than displayed for the following reasons:​

•​

​

​

​

Your vehicle was not perfectly level during fill-up​

•​

​

​

​

Differences in the automatic shut-off points on the fuel pumps at
service stations​

•​

​

​

​

Variations in top-off procedure from one fill-up to another​

•​

​

​

​

Rounding of the displayed values to the nearest gallon (0.1 liter)
1. Drive the vehicle at least 5 miles (8 km) with the speed control
system engaged to display a stabilized average.
2. Record the highway fuel economy for future reference.
It is important to press the RESET control after setting the speed​

control to get accurate highway fuel economy readings.

 

[JeremyH]

LOL. Even if the auto shut offf varried as much as 1% were talkin .1 gallon difference so instead of calcualting 15.6 mpg, you get 15.5 or 15.7. I mean seriously. lol

 

[mulestang]

My experience has been that the car's MPG calculations and my manual MPG calculations have been pretty darned close to each other...22MPG. YMMV
2009 GT 5spd 3.55s K&N panel filter....no tune

 

[Infamous05]

On a trip to VA beach with a/c on and safe tune from
Brenspeed with cai and exhaust

 

[1fastpony]

I know how to do it that way. But I was getting 23 mpg w/ the 4.10's and 20" wheels a few years ago. Now I don't even get 20 highway. Thats why I'm figuring its something mechanical

Did you reset your tune to correct gear/tire rev per mile?
When was the last time you changed plugs, after a yr they tend to get worse gas milage. Mine last about a yr with the bamma tune, its a little on the rich side. Changed out a O2 sensor that was acting up,. a couple of bad plugs after clutch install and reset the revs per mile from the MT DR' to the 555's Nittos and went from 21.5 back to ~25mpg on a level hwy @ 75mph. Getting a third set of plugs and another O2 sensor...car has 56k and almost 6yrs old.

Yes I know how to do mpg calculations.

Also...different volume of ethonal at pump will have an impact.

 

[mrdeath2000]

I used to get 71mpg with my 88 lincoln town car 5.0L... i just went past 88mph (digital speedo cap) and then reset the meter and then coasted. awesome stuff...

 

[Redfireshaker06]

The plugs have not been changed yet. I'm nervous. But I know the longer I wait the worse it will be.

Now, let me ask this. My actual speedo has been under actual speed (Using GPS). With the 4.10s is was about 2 mph difference. Set the Xcal 2 to 3.73's and its about 3 now. Can that afffect any of this? I wouldn't think it would make a difference. OH, and I know I'm rich and I've had 2 different companies tunes.

 

[SilentScope]

use the "gallons used" and "trip meter" functions on the info center to calculate the MPG

 

[Redfireshaker06]

Now this morning on the way to work, the GPS and the speedo matches. lol

 

[s8v4o]

AND.... did you tune for the tires you're on now? You said you used the xcal for the 3.73's but did you tune for the 4.10's to begin with. Your current Xcal/tune settings would help us out a lot. What size tires are you CURRENTLY running, still the 20's?

 

[Redfireshaker06]

Yes, I had it set for the revs and the gears. 255/35/20's all the way around.

 

[1andonlywhitie]

The problem with the pump-click-off method is you are assuming the tank is full each time when the pump clicks off. Different pumps may provide different levels of fill. The tank is never truly full (ie fuel spilling out the filler) when the pump clicks off, and you can usually add more by squeezing the pump lever some more.

What you really need to know is exactly how much fuel was actually consumed over your trip mileage, and that is difficult to do using a refill measurement method, unless you fill the tank repeatedly to the point when the fuel starts to spill out.

The PCM has a PID called FLI, or Fuel Level Indicator. This PID reports the percentage of fuel remaining in the tank to two decimal places, ie 73.28%. This fuel level accuracy combined with the PCM's knowledge of exactly how many miles were traveled should provide for a more accurate calculation than trying to calculate it manually. Can anyone explain why it wouldn't?

I use the trip computer and then divide it by the "Gallons Used".