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I recently got the 3500 159 ext high roof gasoline.
Mileage is poor, around 14. I do hvac. Lots of stops. But even highway mpg is not great.

If I barely hit the accelerator it downshifts. I think it is too fast. I would gladly trade some power for mpg. I tried the semi manual mode. It works the reverse of what I want. It will stay in a lower gear at high rpm, but it wont stay in a higher gear at low rpm. Even in manual mode it downshifts on light acceleration.

Does it actually have no torque below 2500 rpm? or, if a modification was possible, would it accelerate slowly if forced to stay in 6th longer?

I personally think all heavier trucks should me manual transmission- but that is irrelevant.

Lastly, I see the Gforce chip ad here. Does anyone have an opinion on it?
It seems like it would be worth a try for $69
 

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Found this http://thmotorsports.com/sct/sct-x4-power-flash-programmer/7215/i-1985335.aspx?aid=9270727 With promo code SCT its $339.00. Maybe you can custom tune your shift points? But like it says under the description "up to 2 mpg" not sure how long it would take to recoop that money.
When I had a 2012 Ram truck I was on acouple different forms and that G-force chip was brought up often and nothing good was ever said..never tried it myself.
 

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My van is the same as yours. On summer fuel, 70+ mph highway is around 19. Under 60 highway is 21-22 with no hills. I do almost no city mileage, so i cant say but 14 average isnt too bad. Winter fuel makes a big difference.

The shift point are ok, but the downshift situation leaves a lot to be desired. I think whats hurting our city mileage is the throttle mapping; every start is a fuel wasting jackrabbit start. It would be nice to smooth that out.

The manual shift is, as youve discovered, nothing of the sort. Its a high gear lockout.

As to chips, i have little experience but i suspect you get what you pay for. When i first got my pm, i poked around on the jeep wrangler forums guessing that their programmers would work on our pentastar too. Didnt get very far with it.

I have a buddy that works at summit racing. He might know something. Ill chase him down.
 

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I drove from NC to Florida today on I95

I was getting 16-17 on dash reading at 70 mph, then refilled at Florida state line. I was getting 19-20 all down Florida.

Don't think wind changed during drive. Might be summer gas in Florida versus winter gas in NC.

BTW, it was 28 degrees when I left NC this morning. Brakes love to squeal when it's cold. No brake noise in warm Florida.
 

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I've only had my pm for a week and haven't done the math the real way concerning the milage but the dash is saying 13 mpg. I do comercial refrigeration service and carry around a lot of heavy parts and tools, which is most likely the problem. The six is surprisingly strong and the starts from a stop are jack-rabbit- like if you're not careful. The gearing must be low. I like most about it except the seating position and the lack of leg room. I'm only 5 foot eleven but my legs have to stay bent. My old Chev express van had enough room to straighten my legs completely out and stretch on those long drives! With the seat all the way back in my pm, the drivers mirror becomes partially obstructed by the vertical post between the 2 drivers door windows! Someone wasn't thinking about that one. Working out of the back is great though. I hope the transmission will last. My Ford E250 transmission failed 6 times between112,000 miles and 176,000 miles, all in warranty. I'm definitely driving the pm easy.
 

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The I'm
I drove from NC to Florida today on I95

I was getting 16-17 on dash reading at 70 mph, then refilled at Florida state line. I was getting 19-20 all down Florida.

Don't think wind changed during drive. Might be summer gas in Florida versus winter gas in NC.

BTW, it was 28 degrees when I left NC this morning. Brakes love to squeal when it's cold. No brake noise in warm Florida.
I did the eaxct same trip yesterday going from Amelia Isl FL to Smithfield NC!

My dash readout said 19.1 most of the way at 70 but I haven't done the math yet - got gas for $1.94 though in SC and saw it for $1.91 in Jax!

I think I passed you on I95 - white van with black lettering on the side?
 

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White, but no lettering. HOA doesn't allow lettering.

I got raped it SC. $2.49 for gas! I should have gotten back on I-95 and gone to next exit.
 

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I like most about it except the seating position and the lack of leg room. I'm only 5 foot eleven but my legs have to stay bent. My old Chev express van had enough room to straighten my legs completely out and stretch on those long drives! With the seat all the way back in my pm, the drivers mirror becomes partially obstructed by the vertical post between the 2 drivers door windows! Someone wasn't thinking about that one.
Stop trying to emulate the seating position of a car and start trying to emulate the seating position of a chair in your living room.

Pull the seat forward and move it UP until your legs are at a comfortable reach.

Know how I know you have it too far back ... I'm an inch taller and the post for the driver's window is exactly in line with the turn signal on the extreme outside of the left mirror so that the light from the turn signal is blocked and is therefore not distracting. The mirror surface is entirely ahead of that post.

It's comfortable on long trips. I've done 14 hours in one go with only fuel and food/pee stops.
 

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On the subject of the performance/economy chip ...

I doubt if there is much economy to be gained on the highway. Mine spends all the time in 6th and 5th gears on cruise control and the torque converter is locked all the time except for a moment during gear changes (to smooth them out). When an uphill starts getting steeper, it stays in 6th with the converter locked as long as it can, until it actually starts losing speed, so there's nothing to be gained on that count. We are dealing with a gasoline engine pushing a great big heavy box - there's only so much that can be done.

Around town, perhaps it's different, it's hard to tell when the converter is locked. I don't do much driving in those conditions.

The 9-speed transmission would be another matter ... but in hilly areas, it would be shifting even more if it were trying to maintain the optimum gear selection under all conditions.
 

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I drove from NC to Florida today on I95

I was getting 16-17 on dash reading at 70 mph, then refilled at Florida state line. I was getting 19-20 all down Florida.

Don't think wind changed during drive. Might be summer gas in Florida versus winter gas in NC.

BTW, it was 28 degrees when I left NC this morning. Brakes love to squeal when it's cold. No brake noise in warm Florida.
Cold air in winter is also denser, so it creates more aerodynamic drag at highway speeds. And we all know Florida is hot year around, right? I'm in FL at present visiting and it's in the 70s, sunny, and with house AC running. This warm weather can't hurt MPGs.
 

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White, but no lettering. HOA doesn't allow lettering.

I got raped it SC. $2.49 for gas! I should have gotten back on I-95 and gone to next exit.
I just got the same treatment at a SAMs Club in Scranton - $2.45!
 

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I just got the same treatment at a SAMs Club in Scranton - $2.45!
Take satisfaction that you are helping the country to shed that expensive old inventory to make way for the new stuff. In our small town 100 miles south of Phoenix it is still 2.79! I plan my purchase of fuel around leaving town!
 

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Things I've learned as a van driver:

1. Pennsylvania is always expensive for fuel, and worth a trip across the nearest border…except maybe NY.

2. Not sure why, but driving south always gets better mileage than north. Net downhill I guess.

3. Instant MPG readouts are usually wrong, and usually optimistically wrong. Think about this - instead of driving at 60, floor it till it gets to 90, then coast down to 30 and repeat. Common sense will tell you driving like that will kill your mpg, but the readout will average out to 45mpg or something ridiculous.

4. I've been doing this for approaching 15 years, and I STILL can't get a handle on summer/winter fuels and exactly how much they affect mileage. Too many variables I suppose. 2-3 mpg seems like a rational estimate.

5. For strictly highway driving, and assuming you are not in serious mountains, weight does not make much difference in terms of mileage. Running heavy can sometimes even help mileage because it acts as a sort of capacitor on hills. In the city, total opposite effect.

6. Lastly, never EVER buy those rotating hot dogs at truck stops. It's hot meat spinning for days! It's like a petri dish! What are you, nuts?
 
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The simple explanation to why you get less MPG on winter fuel is simple. By adding ethanol it lowers the BTU's of the fuel, or the amount of heat produced. Since the BTU's are lower, it requires more fuel to for the engine to reach its proper air/fuel ratio. More fuel, less MPG. Same reason you use more premium fuel than regular. Summer fuel has less ethanol.

The thinking behind the add of ethanol was when cars had carburetors and had issues staring in the cold. Ethanol is very flammable and would allow the engine to start quickly. For those old enough, will remember that can of starter fluid in most cars of the 70's! So with almost all vehicles today fuel injected there is no need for it now. Its just a gov't deal for the farmers that grow corn to make the ethanol. Remember E85?

My PM gets on average around town between 13 and 15. On the highway it gets around 18 with it loaded.
 

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Are we certain that the only difference between summer and winter gas is ethanol? Im no chemist, but ethanol increases octane rating, said another way it decreases volatility. Thats why e85 has an "octane" rating up over 100. Wouldnt you want more volatility in the winter, not less?

Also, ethanol runs cooler and foesnt burn as hot (less btu per gallon). Wouldnt you not want that in winter?

As a side note, i see jay leno complaing all the time about ethanol. Turns out CA has had ethanol since the early 80s, just like the rest of the country. Hes only moticed because CARB look the dpec up to e10 from e5. But in the midwest, weve had e10 since the carter administration.
 

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It can't be ethanol. We've had winter gas long before ethanol was allowed in gas. Remember, cars couldn't run ethanol in the old days. Manufacturers had to make material changes to allow it.
 

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12.5 mpg average at 70 mph cruise on level Interstate in Florida. It continually downshifts to 5th. Instant fuel economy is 14mpg in 6th, 12 mpg in 5th, 10 mpg in 4th. I think there is 10% ethanol in the gas so 3% less energy. On the first tank after I bought this 8500 lb RV in NOLA it got 14.5 mpg; close to refineries maybe no ethanol?
 

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with my itasca rv I'm getting 13 to 14 pulling a 5x8 enclosed. The thing shifts constantly 5th 6th 5th 6th! Manual does nothing and the tow haul just seems to keep it in 5 longer. I wonder how long the tranny will hold? They are a great unit with plenty of power. I was looking here to see if any one has a chip installed to help with the shifting or getting a little more out of it in 6th. 6th gear doesn't have enough power to push the air drag in the PM rv version. I think the aerodynamics with the trailer helps the mpg. I get less with out it. Any one have a chip yet? I like the airbag suspension setup on eBay. MarkD do you think the airbags will increase the load capacity?
 
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