D2: less than 200 miles per tank....

[Denisk]

Hey Guys,
My 01 D2 SE, 57K, (everything relevant is stock) is getting very thirsty! I've searched but cant see anything directly related.

Details: its city driving, short trips mostly for errands, cold weather now (WDC area), but i started noticing i get only around 200 miles between the yellow light - low fuel indicator and subsequent stops for gas. Is this me or is this weird? No warnings lights were/are on, no huge leaks of oil, Oxygen sensors appear to be relatively dry outside as opposed to be all ridiculed with oil dripping from the gasket, liquids are all at OK levels, change oil / rotate regularly, 16-inch rims, tires are at factory recommended settings (28psi fronts - 46 psi rears).
I just dont know where even to start investigating this.... Any ideas, suggestions would be very very appreciated.

PS: Just replaced the front drive shaft, noticed nothing out of the ordinary when inspecting from underneath, no major leaks..... One thing is that I dont even know when did i change the air filter last, but would this matter to such an extent?

Tanks much in advance.

 

[rmuller]

Do a tuneup, Magnecore 8mms + Champion plugs and make sure your O2 sensors are good... I get about the same mileage, but I'm on 33s w/ a ton of crap bolted onto my truck.

 

[Surf]

I get about 350 miles until the light comes on in a 2002 SD with 2" RTE lift, and slighty larger than stock Michelin LTX's. This is usually a mix of both city and highway.

Truck has 107k miles on it too.

 

[ptschram]

An unexplainable loss of fuel economy is most likely oxygen sensors. That said, I'd expect a DII to have a little flag that came up and told you to replace your oxygen sensors.

 

[rmuller]

I get about 350 miles until the light comes on in a 2002 SD with 2" RTE lift, and slighty larger than stock Michelin LTX's. This is usually a mix of both city and highway.

Truck has 107k miles on it too.

350miles? Jesus.. I usually travel with other modded D2s when we go wheelin', and even straight highway, we all average about 13mpg there... about 10mpg city. Trucks are constantly maintained as well. Around town I see 9/10mpg ... this is even after adjusting for the difference in speedometer versus GPS.

 

[Denisk]

An unexplainable loss of fuel economy is most likely oxygen sensors. That said, I'd expect a DII to have a little flag that came up and told you to replace your oxygen sensors.

Me too! In other words, isnt "a little flag" like this should be one of the many functions of the "check engine" light? A few winters ago (knock on wood) I saw it on briefly when it was really really cold one night - to never show up again during normal use.

So the question is: how do I check the darn oxygen sensors? If i recall correctly some welding equipment is needed to replace them?

Thanks to all, guys!
PS: I do get better mileages on long trips to NY or to OBX (around +/- 260 miles per tank), but this just made me worry that something else on my truck is quietly failing on me... And my driving style for D2 is equal to driving a school bus...

 

[Thunderhand]

One thing is that I dont even know when did i change the air filter last, but would this matter to such an extent?

I've had to change mine every 5000 miles to keep from dropping m.p.g. Need a freakin snorkel.

 

[Surf]

350miles? Jesus.. I usually travel with other modded D2s when we go wheelin', and even straight highway, we all average about 13mpg there... about 10mpg city. Trucks are constantly maintained as well. Around town I see 9/10mpg ... this is even after adjusting for the difference in speedometer versus GPS.

The difference in leaving it in sport mode and regular mode seems to make a difference. It's better in sport mode without a doubt. I also don't accelerate very hard about 99% of the time. I try to take it easy on the skinny pedal.

 

[built2crawl]

I have had the same issue since my headgaskets were replaced. I also always replace air filter, clean TB & MAF at every oil change. I'll try changing the O2 sensors to see if it makes a difference.

 

[kennith]

Check the hood badge, sometimes Land Rover appears there.

Cheers,

Kennith

 

[WNYDiscoIIErik]

MAF sensor?

 

[benlittle]

X2 on the O2 sensors

 

[Ataraxia]

A few months back I was getting brutal milage.

Turned out to be sticky calipers. Pretty much all 4 corners were sketchy. A few ripped piston boots, scored gland seals and seized slider pins. All due to age, but mostly dried mud/clay cutting the shit out of everything.

 

[Steph]

My mileage had dropped after a head gasket job also. It ended up being a plug wire that wasn't attached firmly at the coil pack. Pushed it back and saw a big difference at the next fuel tank.

 

[built2crawl]

My mileage had dropped after a head gasket job also. It ended up being a plug wire that wasn't attached firmly at the coil pack. Pushed it back and saw a big difference at the next fuel tank.

Thanks for posting this. Found the plug wire closest to the pass side firewall was not plugged in all the way. I pushed in the plug boot and felt it snap onto the plug. I tried checking the coil pack, but I couldn't get my hand back there.

 

[rcshauger]

hope this helps... I love simple fixes. They come so infrequently on our beasts.

 

[scottagnew101]

I'm getting pretty good mpg with a 2" lift and 31's. Make sure you are changing the fluids on time. The largest increase in miles driven to a tank was when I used BG products ( 44K or CF5 depending on what's around) it increased me to 240-260 now I get atleast 320 if not 335.

Scott

 

[adriatic04]

The difference in leaving it in sport mode and regular mode seems to make a difference. It's better in sport mode without a doubt. I also don't accelerate very hard about 99% of the time. I try to take it easy on the skinny pedal.

I havent tried myself, but I could have sworn I heard from others who compared, that sport mode was actually worse on MPG?

If I drive full tank hwy I can do over 400 from time to time, sometimes my cty MPG drops though, seems to make a big difference on which fuel I run too, shell vpower gets me a good bit more.

 

[Slappy]

I think he said it best in the first few sentences. Short trips and city driving. Mine gets bad mileage because my drive to work is very short (barely enough time to warm up), but when I'm highway driving I get excellent mileage. Also when my low fuel light comes on I still have @ five gallons left in the tank. Food for thought.

Steve

 

[Sin39]

400 miles on 1 tank. That is insane. The best I ever saw on my '00 was 350, with about 1.5 gallons left when I filled up, this was all highway driving, mostly tooling around secondary roads in the middle of nowehere at about 50mph.