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How To Adjust Your Indicated Average Fuel Economy

Mustang_Lou

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I'll have my fuel economy displayed in l/100km (not in mpg). So for me if my real calculated economy is lower than what the car will display I'll have the bias number other way round (Real: 20l/100km; Car: 18l/100km). So my calculated bias would be 0,9. But if I did calculations in mpg it would be 1,111. That is because I calculate fuel per distance and (in US) you calculate distance per fuel. What number should I use in setting the correction value. Can someone who uses l/100km measure tell me?
That's interesting as here in Canada we also measure it in L/100 km. I set mine down to .9xxx but haven't driven it enough with this never-ending winter to know if I'm going the correct way or not.

I think I am as the car's # was higher than actual calculated so I think the car's formula is just applying a .9xx factor to what IT calculates to bring it to a more realistic figure.
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Hooch180

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I calculated it wrong way in my post. What I meant was that l/100km and mpg will grow in oposite direction. So 15 l/100km is 19mpg but 20l/100km is 14mpg. This way if your is showing 15mpg but in reality it is 14mpg then in makes sence to put 0.933 multiplier. But for the same scenario if calculated from l/100km it would be 1.333. Now important part is. How this multiplier is used. I would assume that (because you can change units in settings) that this multiplier would not change. So my pure guess is that for mpg and l/100km it would be the same 0.933.
 

Intrepid175

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I calculated it wrong way in my post. What I meant was that l/100km and mpg will grow in oposite direction. So 15 l/100km is 19mpg but 20l/100km is 14mpg. This way if your is showing 15mpg but in reality it is 14mpg then in makes sence to put 0.933 multiplier. But for the same scenario if calculated from l/100km it would be 1.333. Now important part is. How this multiplier is used. I would assume that (because you can change units in settings) that this multiplier would not change. So my pure guess is that for mpg and l/100km it would be the same 0.933.
Divide the low number by the high number. In my case (mpg) that means divide my calculations by the computers calculations because my numbers are (so far) always lower than the computers numbers are. For L/100km, it'll be the other way around. Divide the computers calculations by your calculations. The reason it's reversed is one is calculating distance covered by a fixed amount of fuel and the other is amount of fuel consumed for a fixed distance..

Using your example, 14 mpg / 19 mpg = 0.736. 15 L/100km / 20 L/100km = 0.75 I did a conversion search on your numbers and came up with 15 L/100km = 15.68 mpg. 20 L/100km = 11.76 mpg.

Using those numbers 11.76 mpg (my calcs) / 15.68 mpg (computers calcs) = 0.75 while 15 L/100km (computers calcs) / 20 L/100km (my calcs) = 0.75. That's how I'd do it.

Hope this makes sense!
 

sZedely

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Anyone know how to get into "Engineering Mode" on a 2018/2019 Mustang GT with the 4" display? The posted processes on these forums are for pre-2018 Mustangs and does not work.

I'm going to continue to do some more digging myself. Will post instructions if I find a working procedure.
 

Rash

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Anyone know how to get into "Engineering Mode" on a 2018/2019 Mustang GT with the 4" display? The posted processes on these forums are for pre-2018 Mustangs and does not work.

I'm going to continue to do some more digging myself. Will post instructions if I find a working procedure.
It worked on my 18 but I have ditgital dash - dont know if that matters
 

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sZedely

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Engineering Test Mode

  1. Begin with the ignition OFF and all doors closed.
  2. Press and hold the steering wheel switch "OK" button.
  3. While holding down the "OK" button, press the ignition button once. Do not press the clutch or brake pedals while doing this. Continue to hold the "OK" button for another 5-8 seconds until the dash displays a red "ET" at the bottom of the main message center display ( on an analog IPC). If you have a digital IPC, the "ET" will be in the rotating display on the lower right-hand side.
  4. Press the up or down arrow buttons to navigate through each of the display windows.
  5. Each down arrow button press advances the viewing window to the next set of items.
  6. To exit the Engineering Test Mode, press and hold the OK button for 5-8 seconds or turn off the ignition.

*My issue getting into "Engineering Test Mode" was that my vehicle is a manual and had a pop-up to press the clutch. I didn't see the "ET" at the bottom, I was expecting to see the main menu for the "Engineering Test Mode". Make sure to watch for the "ET" next to the battery indicator and acknowledge each pop-up with the OK button once. Then you will see the main menu for "Engineering Test Mode".
 
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Intrepid175

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It worked on my 18 but I have ditgital dash - dont know if that matters
None of the 15-17 year models have the digital dash so I doubt that makes any difference.
 

munizfire

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Would be neat to have the car 'trick' me into thinking I was doing a higher MPG than I actually am; by displaying a 'fake' higher fuel economy. Which kind of is the opposite of this thread.

In all seriousness, it could be worse, my GT Premium (M6) is doing an avg of 19MPG, and I drive aprx. 75% of the time in traffic jams, and the other 25% is long roadtrips. However, I'm always driving very cautiously, I rarely floor the car, but I'm pretty sure that's going to change when I get an exhaust /giggles
 

Intrepid175

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I've been tweeking mine. The last couple of full-ups have only been 0.1 mpg off between the computer and my calculations. I think I'm done! :)
 

Mustang_Lou

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Would be neat to have the car 'trick' me into thinking I was doing a higher MPG than I actually am; by displaying a 'fake' higher fuel economy. Which kind of is the opposite of this thread.
Just go in the opposite direction so enter 1.2 for example.
 

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munizfire

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Just go in the opposite direction so enter 1.2 for example.
Interesting... and if I do that, I can always revert to '1000' to show the mpg calculated by the car, as if nothing ever happened; or would that sort of affect the calculations of the computer? Seems like I could have some fun with this
 

Rash

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Maybe dumb question but ... if I’ve already made the adjustment, and then want to make a further adjustment, do I need to go back in and remove the first adjustment and start from scratch, or does the adjusted mpg become the new baseline to make adjustments to?
 

munizfire

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Maybe dumb question but ... if I’ve already made the adjustment, and then want to make a further adjustment, do I need to go back in and remove the first adjustment and start from scratch, or does the adjusted mpg become the new baseline to make adjustments to?
Well, I played with this for a while and from what I gathered, (and answering my own previous question as well) the bias you set stays 'put' and you can later change it. For example, I initially set the Bias to 950, and the MPG lowered a bit; then changed it to 1100 and the MPG increased somewhat. Then I set it back at 1000 and the mpg went back to exactly what it was before I started 'playing' with it. HOWEVER, I DID NOT DRIVE THE CAR, but I think it wouldn't affect it.
 

Mustang_Lou

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Yeah, think of it as a variable in a math calculation. The car's computer has it's calculation done with the variable equal to 1,000. So anytime you change that variable in the menu, it just changes the variable to whatever you changed it to in the calculation.

For example, if the car's computer showed 16 mpg BEFORE you changed anything, the calculation is 16mpg x 1,000 / 1,000.

Change that variable to 1,100 and the calculation becomes 16mpg x 1,100 / 1,000 = 17.6 mpg, which explains why munizfire saw an improvement without driving the car. It's just a math calculation. The key is to get the computers math calculation to be more realistic and that is what this variable is for.
 

Commbubba19

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the problem is hand calculations are based on the amount of gas you filled up with. not the actual amount used. the amount you fill up with may not always equate to the actual amount of gas used, especially if you use different pumps at different stations.
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