how to drive for best mileage

['93BajaSport]

it can't be most gas efficient to drive around town putting 3/4 throttle down out of every stop..

Using relatively arbitrary durations, I crunched the numbers and accelerating for 10sec at 60hp does in fact use about 5% less fuel than accelerating at 30hp for 20sec based on the VW's BSFC chart.

It's one of those "it's true on paper" things, but not usually easy nor practical in real driving. I wouldn't mind having BSFC charts for the various Ford engines, but they aren't typically published for gasoline burners.

 

[AllanD]

I did the short shift easy on the go pedal and got 21 MPG

I just filled it tonight and this time I didnt short shift it - I let it spin up to 2500-2800 before shifting and never let the RPM go below 2k and I got 21mpg....

The 4.0L is a short stroke and short stroke motors dont like to be run low in the RPM range. My 4.0L doesnt make any power below 2k. My 3.0L pulled MUCH better than the 4.0L at 1500 RPM.......

Rob

Time for me to make another "Are you on drugs" post here....

Is this guy actually claiming that a 3.0 has more grunt down
low than a 3.0?

There is no arguement that a 3.0 is a torueless wonder capable
of making a whopping 160ft/lb @ the creeping speed of 3000rpm.

the 2.9 makes peak torque at 2600rpm, that peak torque is 170ft/lb

The 4.0 is making 170ft/lb by 1200rpm and 200ft/lb before 1500
and doesn't make less than 200ft/lb at any point before it hits
the rev limiter at 4650rpm.
and the exact torque peak of a 4.0 is argueable because it's making
220ftlb for more than 1000rpm and slight tuning changes can move
where it spikes up to 225ft/lb.

For an embarrassing part of it's power band a 4.0 actually makes more
torque than a 5.0 can make at a similar rpm.

Remember that for all the "power" of a 5.0 it makes it's peak
torque at 3450!

As for my own driving habits I rarely let me engine get
below 2000rpm except in 1st gear when just getting going.

And I find that my highway mileage goes to shit when I go above 2500rpm.

As for upshifting rpm? depends on why you are accelerating.
If you are in town and going from red light to redlight you are basically screwed, but if accelerating ont a freeway and intending to cross a state or two anthing short of wide open throttle (and open loop operation) the harder you accelerate to your intended cruising speed the better.
The idea is that while you burn more fuel while accelerating you spend less time accelerating and more time at part throttle cruise.

MY Mileage? worst to date in my 4.0 powered 4x4 supercab
(with 4.10 gears! is 17.2mpg.

Generally bashing around I get 19-20.

If I avoid town and stick to the rural roads I get better.

MY best is over 22mpg.


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['93BajaSport]

One "gotcha" when using the hard acceleration method is acceleration and deceleration enrichments in the fueling strategy. Fast throttle changes, either pushing down or releasing, can trigger the increased pulse width and negate the effects of lower BSFC from using more throttle for a shorter time.
I do not know what the rate of change threshold from TPS signal is for the various Ranger/Explorer engines, but it is worth considering.

 

[Beanmachine7000]

When taking off at a stand still I usually run my 4.0 up to about 3500rpm, and try and drive as close the 2500rpm as I can... Anytime it drops below 2000rpm gas mileage goes down considerably... I usually get ~16-18 in town... I got 21mpg on a recent trip on the interstate...

 

[AllanD]

You can close the throttle as abrubtly as you like but you don't open it too fast or you might as well mash it all the way down, because as yousay an abrubt increase will trip it into open loop management.

Best cruise is indeed >2000 <2500

I'm regearing my truck to accomodate that.

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[MAranger]

I go by two thirds throttle up to 2500rpm, up to cruise. I pick the highest gear without lugging the piss out it. If you need to accelerate, do it quickly from 2 grand up. Any hill grab 5th and coast, cause the injectors will be shutdown completely, as I understand it, correct me if I'm wrong. I average 18 combined city highway on a 94 4.0, 184k on it.

 

[fastpakr]

No reason to go into 5th gear for coasting down a hill. The strategy is based on being above a certain RPM (2000?) and the TPS measuring a closed throttle. You're actually a lot more likely to go into the fuel shutdown mode in a lower gear than a higher one.

 

[Ozwynn]

get a manifold pressure gauge or a vacuum gauge and keep it in the green.

my bronco has 3.55 with 33" tires. that being said I never have the OD on unless I am going to be on the freeway. I get 14 - 16 (since I got the hubs to function properly) with a 302 turning 33s via 3.55 ratio thats good in anybodies book.

 

[AllanD]

Personally I knida like cruise control.

I wouldn't head out for Wyoming without it.

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