I'm trying to figure out why i get worse fuel mileage on the freeway than in town? Iget 200-230 miles per tank in town and about 170-180 on the freeway doing 75mph.Any suggestions?

 

Hmmm, mpg sounds off. I'm not familiar with the 96 models, does your truck have a turbo? I wonder if fuel mileage start to degrade if the turbo looses performance? I only have a 29 gal tank and I get about 375 to 400 miles (city) before my low fuel light comes on. I'll go 500 miles easy if I keep it under 62 or 63 mph. If I cruise around 75 mph, then my mileage drops way down to 12 or 13 mpg.

What is your actual mpg?

 

yeah it has a turbo, they have for quite sometime. That is odd, at 75 my 96 is still getting like 17MPG, but i have a 3.55 rearend and a 5 spd too.

 

It's puzzling to me. My truck gets considerably better mpg on the freeway than around town, but I only drive 70. I recently checked my freeway mileage, and I got 19.2 mpg. Around town, I normally get 16.5. I'd check your actual mpg for a few tanks and see what you get.

 

Last time i check my fuel mileage i got 16-18 in town.On the freeway i dont know but its lower than that.I'm not sure what gears i have but i know they are stock,i have 33 inch tires also pretty close to stock size.This sucks.

 

Jozey,

There are many factors that contribute to fuel mileage. I've been watching minc very closely for the past 40000 miles. I've calculated 98% of those miles into fuel consumption. Rpm's seem to have everything to do with fuel consumption. At least with my truck anyway. I can carry a load and not seem to affect my mileage much. But, as soon as I start to go over 70 mph I'll loose efficiency. It seems that the best mileage has been when traffic held me down to 45-55 mph on part of the tank. I have no problem idling for a few minutes when the engine is cold. I keep it under 1000 prm's untill it warms up a bit, or untill I'm on the freeway. It seems that showing off with my truck is useless. All I end up doing is spraying black soot on all lanes of traffic behind me. The vw bus may loose the race but i just spit out a bunch of fuel and slickened the roads.
Calculating each tank at fill up is the only way to get a handle on driving conditions and efficiency.
What is your rear end ratio? There are posts here that claim 25 mpg's. I believe them now that I've done my best to drive conservatively. ( no I'm not holding up traffic. I'm often in the hov lane passing everyone else.
I have no mods aside from a K & N filter. ( a big no-no they all say) It seems to keep my intake walls clean! I have a 4:10 limited slip rear that just wants to pull big heavy stuff but is stuck with me commuting 90 miles per day.
Boy, would a 355 rear be fun!
My worst tank driving with the bed empty was @ 75-80 mph fighting a headwind: 15.8, if I rember correctly.
My best tank was last week, 21.5 with an ocasional load of firewood but mostly commuting with a few days of slow but steady traffic. Some stop and go too!
The last few tanks were: 21.5, 18, 19, 20.5, 19.7
Let me know how you make out on the next few fill up's.

 

I've learned on this forum that keeping the RPM's under 2000 or so will give you the best fuel economy. I'm starting to see that myself. Typically, 70MPH highway driving gives me approx 16.5-17 MPG (approx 2300 RPM). However, If I keep it under 2000 RPM(63 MPH or less), it seems my MPG climbs to 18 and some change! Most recently, I towed a 2500LB trailer with approx 1000 LBS of cargo on it approx 400 miles. MOst of that was interstate driving, but I kept the speed to approx 60 MPH and I still got 17 MPG! Not that 3500LBs is much for a stroke, but it goes to show ya about RPM and Fuel economy!

 

Born with a Hammer: "It seems that showing off with my truck is useless. All I end up doing is spraying black soot on all lanes of traffic behind me. The vw bus may loose the race but i just spit out a bunch of fuel and slickened the roads. "

And the problem with that is.... black soot is waaay cool, makes me feel like I'm Bond, James Bond only in a tricked out pick 'em up.

Seriuosly though, I agree with you up and down the line on the efficiency - it mirrors my experience exactly. 55-65 ideal, >70 mileage drops off, >>75 what mileage? 3.73LS and a Banks kit, I get what I get, but with a bunch more pop than it used to have - no mileage improvement.

 

1BADF350-How much boost do you see when you drop the hammer with your Stinger Kit?

 

Diesel Daddy, thats what i've been doing,i have notice a change in mileage if i go slower(65-70) but the thing that gets me is my freind has a 01 250 4x4 and he pulls a 40ft toy hauler when we go do the dunes.He will get alittle better fuel mileage than me and i only have about 400lbs in the bed(which isn't sh**) and we'll do 75-80 sometimes but try to stay around 75mph.I just dont get it

 

Jozey, it may be because he has the 3.73 rear instead of the 4.10. That will make a difference.

 

Daddy - I put my gauges in first and saw max stock was about 15psig with K&N filter. After the Banks kit it goes to 25psig max and the acceleration is down right scary from 40-65.

The kit I bought was a Stinger Plus, the installer had a problem getting "power" out of the kit during install and put a PowerPack chip in it - I don't know what the difference is other than probably fuel curves. Basically I ended up with a PowerPack kit less the intercooler, which Banks didn't recommend unless I was towing a lot. No drop in mileage, except for my more prominent lead foot now...

 

1BadF350, just curious, what type of exhaust set up do you have?