then I wouldn't buy or add anything till you solve the current problem. Never mask an issue by compensation.
2000 magnum
- Thread starter Rodsaknockin
- Start date
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Bobzilla
Well-Known Member
Can you guys all provide more vehicle info?
What gear ratios, transmissions, speeds the fuel mileage is veing judged, and what octane fuel and alcohol content of fuel in your area for these mileages you are getting?
My first 1999 Ram 2500 with 5.9 Magnum has 4:10 gears, four wheel drive, overdrive auto trans, and larger than stock tires. This truck always about 11 mpg at 75-80 mph speeds, and would barely reach 13 mpg at 65-70 mph.
My current 1999 Ram 1500 with 5.9 Magnum also has four wheel drive, overdrive auto trans, larger than stock tires, and I think it has 3:54 gearing. This one gets 13 mpg at 75-80 mph speeds.
My old 1993 D250 with 5.9 Magnum is two wheel drive, overdrive auto trans, 4:10 gears, stock tire size. That one never did better than about 14 mpg at 75-80 mph.
All my trucks have run regular unleaded when not towing, which is usually 87 octane with 10% alcohol here in Michigan.
What gear ratios, transmissions, speeds the fuel mileage is veing judged, and what octane fuel and alcohol content of fuel in your area for these mileages you are getting?
My first 1999 Ram 2500 with 5.9 Magnum has 4:10 gears, four wheel drive, overdrive auto trans, and larger than stock tires. This truck always about 11 mpg at 75-80 mph speeds, and would barely reach 13 mpg at 65-70 mph.
My current 1999 Ram 1500 with 5.9 Magnum also has four wheel drive, overdrive auto trans, larger than stock tires, and I think it has 3:54 gearing. This one gets 13 mpg at 75-80 mph speeds.
My old 1993 D250 with 5.9 Magnum is two wheel drive, overdrive auto trans, 4:10 gears, stock tire size. That one never did better than about 14 mpg at 75-80 mph.
All my trucks have run regular unleaded when not towing, which is usually 87 octane with 10% alcohol here in Michigan.
75-80 mph is going to kill gas mileage. My 2wd 3/4 ton gets 18 at 55-60 mph. That's some small town driving along with commuting to work or wherever. I have 3.55's, automatic
T56MaxTorq
Well-Known Member
As long as you have a heavy 4x4 truck with 35” tires and are hauling a load, you’re not going anywhere quickly or with good fuel economy. You could put a 400 hp crate engine in it and it will be a dog without a torque converter and new gearing.
How are you calculating your fuel mileage? The only way is by getting mileage by gps and measuring the fuel that goes in. Using the odometer and topping off the fuel tank is a wild guess with bigger tires.
How are you calculating your fuel mileage? The only way is by getting mileage by gps and measuring the fuel that goes in. Using the odometer and topping off the fuel tank is a wild guess with bigger tires.
correct. With 35's, he killed gearing, and he is actually going further than the odometer said. Mine has factory LT245/75/16 - not sure of height, must be about 30"
Rodsaknockin
Well-Known Member
The tires are 265/75r17 so they are only 31.5" tall tire I put 17" wheels on in to match our other Diesle trucks with 17" rubber it had 245/75r16s before very close to the same height no change in mileage . I will say that it does seem some what better since we got rid of the cat. I will check it again when we get it out
Bobzilla
Well-Known Member
When the cat plugged up on my 1999 Ram 2500, it sounded normal but felt like it was pulling a 10,000 lb trailer all the time. Didn't realize it was losing power until it got pretty bad. Replacing that cat really helped, but that truck never had impressive power.
My current 99 Ram 1500 is not programmed for the tire size, but I did program the 2500 for the tires right after I got in about 2001.
For comparison, my current primary truck is a 2008 Ram 1500, four wheel drive, five speed auto trans, and 100% stock, including tire size. The 5.7 Hemi with cylinder deactivation still only gets 15 mpg at 75-80 mph. I checked this one once at mostly 60 mph on a long trip and it was averaging 19 mpg for a few tanks of gas.
You'll get run over if you are only going 55 mph on southeast Michigan freeways.
My current 99 Ram 1500 is not programmed for the tire size, but I did program the 2500 for the tires right after I got in about 2001.
For comparison, my current primary truck is a 2008 Ram 1500, four wheel drive, five speed auto trans, and 100% stock, including tire size. The 5.7 Hemi with cylinder deactivation still only gets 15 mpg at 75-80 mph. I checked this one once at mostly 60 mph on a long trip and it was averaging 19 mpg for a few tanks of gas.
You'll get run over if you are only going 55 mph on southeast Michigan freeways.
Bobzilla
Well-Known Member
Magnum engines don't have knock sensors. That's one of the reasons the factory tunes were so soft. Later models had even softer tunes and some 2000 and maybe other years go a soft tune as a service campain. That would have a sticker on the radiator support or the PCM itself. Don't remember if that reflash was all v8 Magnums or just the 5.2 liter. Some call it the death flash because it killed power. Supposedly it was a bandaid fix for the intake plate vacuum leak that caused a lot of spark knock in some of them.
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