I just bought a reprogrammer, set it on 87 octane, and ran a tank full of gas through her. Then, after the computer got adjusted, I filled up again and began to check my mileage, and found I get 15 mpg. Today, I filled up on 93 ( after getting her down to fumes), and reprogrammed for 93. After a tank full, I'll fill up again and begin to check mileage. I get company gas, and my boss said if I can prove the mileage offsets the cost, I can keep getting 93. I figure 1.5 mpg will justify the extra $4 over a tank full. I am now taking bets.. 87 or 93?

 

hmmmm crazy man, i bet 93, my truck runs alot better on it with my programmer, what programmer you have.

 

i say 87.because you wont be able to keep your foot out of it.lol

and to add, i was getting better gas mileage with my old hypertech max energy programmer than my superchip 3815 is now.both on the performance setting.but the 3815 has a little more butt.

 

you probably don't want to hear this
but if you are just going to check tank to tank MPG
it jumps around so much
that it will take six tanks of 87 octane
to get a good comparison
to six tanks of 93 octane

if you just compare one tank of 87 octane
to the next tank with 93 octane
it will be a crapshoot about which one gets better MPG
... more random chance than a test
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old post
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Here's the results of several tanks of gasoline I kept track of with the OD
either on or off in city driving. After each tank fill up, I alternated
keeping the OD on or off.

I have since made 3 more 300 mile long mpg tests in city driving since i
posted the original 6 tests. My test results now look like this:
-----------
OD turned off runs:

7-19-00 14.32 mpg Amoco87
7-29-00 15.17 mpg Amoco87
8-08-00 14.23 mpg Amoco87
9-08-00 13.53 mpg Amoco87
---------------------------------
average 14.31 mpg
Standard Deviation =0.67

OD turned on runs:
(these were run inbetween the runs above)

7-12-00 14.16 mpg Exxon87
8-17-00 14.25 mpg Amoco87
8-24-00 15.49 mpg Amoco87
9-01-00 15.03 mpg Amoco87
9-12-00 14.35 mpg Amoco87
-------------------------------
average 14.66 mpg

As you can see, so far the OD on/off difference seems to be small with a
slight 0.3 MPG edge to leaving OD on while in city driving.

That is about a 2% difference and may be due to 'scatter.'

The difference between driving with OD on, or OD off, is that with
OD off the auto trans will quickly 'lock up' the torque converter clutch in
3rd gear,
but with OD on in daily driving 3rd gear will be with a slipping torque
converter and the TCC won't lock until you get in 4th OD gear above 50 mph.

Note also how much the MPG jumps around.
All realworld tests have 'random variation.'

The Standard Deviation of all 9 tanks of gasoline = 0.61
and the average of all 9 tanks was 14.50
so that 98% of the time
the MPG will 'naturally' be expected to jump around
in a range from 13.3 to 15.7

If I had done just two tests, and had by chance gotten the low 14.16 for the
OD on, and the high 15.17 for OD off, I would have falsely concluded that OD
on really hurts in city driving.

To get more reliable MPG numbers for Rams in city driving you need to do
multiple tests in a before/after/before/after sequence.