without OD - better mileage ?

[lizzyhermit]

just a casual observation but since I've started turning off OD while driving under 60 mph my city mileage has improved from 14. 6 to 15. 8 average.



does that make sense ?

 

[KatDiesel]

Yep

 

[Jar Head]

Nope

I tried that and went from 15. 5 to 14. 3 mpg. I have 4. 10's.

 

[KatDiesel]

I have 4. 10's with 285/75/16 tires (makes it 3. 95). I keep overdrive locked out under 55mph and I get bout 15mpg around town.

 

[chuck3]

No

I've been doing the same and mine dropped a little.

 

[JTroiano]

I got 315/65R16's and 3:55's and I drive in any one of my 5 gears and got 17mpg in the city on the last tank.

Jon

 

[BigDaddy]

I too see a drop in MPG with OD off. I may get lower milage around town, but I know it's better for the engine

 

[cbconway]

I do mostly city/expressway driving. With OD now off under 55, I went from 15 to 16 MPG (empty). I like the no lugging, too.

 

[xcucv]

I agree that OD off under 55 is perhaps a good thing however I was wondering if there was a way to manage this other than just monitoring the MPH. While I try to keep it off sometime I catch myself quite a bit above 55 before turing OD back on. Is there any way to modify the factory shift at 45 to anything higher.

Thanks

 

[Fireman]

What's city driving ?



Fireman

 

[Steve Campbell]

I have a stick shift, but this discussion makes me think about a modification "someone" might come up with. I have the trip computer and have done a lot of comparing MPG in 3-4 and 4-5 in different situations and find suprizingly that a lot of times a lower gear shows up as better mileage on the computer. Could "someone" fashion a device to sense the "max MPG" and shift the transmission (automatic) accordingly? My little cranium can't even begin to comprehend the wiring/sensor mess required. I read a lot of people are more interested in power production. Sometimes (for some of us) it would be nice to hit a button (I would not have to 'think' about what my right foot is doing) and just see how far the fuel mileage numbers could be stretched.

 

[pwr2tow]

The only corilation I see so far is 98. 5 trucks get better mileage with OD off under 55MPH while the 2000 and newer trucks get worse mileage with OD off under 55MPH. Could be something in the ECM programs. This is just my theory from what the above posts state, more people posting to this thread will prove or disprove my theory, it is interesting though. I have not tried this but I will be in the future.



Ron