I have an 02' that I have always seemed to get really low gas mileage on....Right now driving it around town & going as easy on the gas as possibe I'm only getting right at a little under 14mpg.....A few years ago I towed about a 5,000 lb trailer from Oregon to Alabama & the truck was getting right at 14mpg on the whole trip....

Doesn't 14mpg driving in town seem a little low for these trucks or is this normal? I've been running 2-stroke oil in my diesel for the past 6 months or so, but I've not really seen any gains in gas mileage at all.....

 

14 sounds a little low.

Consider cleaning the IAT sensor, and adding an additive like Power Service or something to increase the cetane a little and clean the injectors.

I get about 15 around town in winter and about 16 avg when the winter blend runs out.

 

There's lots of variables which can cause lower fuel mileage. If there's over 150,000 miles on the engine then consider a valve adjustment. Possibly the injectors need to be looked at. Tires can affect mileage and incorrect speedo from tire sizes too. Winter fuel can affect fuel mileage by up to 10% and ULSD has a lower BTU rating which affected fuel mileage up to 10% also. Low fuel pressure can affect mileage as well as an APPS sensor out of adjustment. And as SIXSLUG mentioned, the IAT can be dirty, but thats usually a problem on trucks with exhaust brakes.

 

After looking at his sig I can't imagine stock sized tires on that rig.

That would be pretty good mileage with taller heavier tires, which could also cause the trans to wear out quicker.

 

14mpg is all that I get on winter blend in my 01. In summer I get 17 city driving.

 

where's the iat sensor?

 

Thanks for the replies everyone.....

Funny thing is that 14mpg seems to be what i have gotten on this truck since it was new....I am still running the stock tires 265/75 R16....Only thing that has been modified on truck is it has about a 3" lift up front....I run a FASS DDRP lift pump....Fuel pressure pretty much always stays above 14 no matter what.....

I pulled the IAT sensor out & it was as clean as could be & was still pretty much white......Also, have done a valve adjustment on it but it wasn't necessary....Valves were pretty much right where they should have been....This truck has 40,000 miles on it right now.....

I used to run Stanadyne Performance Formula....Didn't notice any mileage improvement....Truck just seemed to start very smooth when running it.....I started running the 2-Stroke after learning that it could help out in the life of the injection pump....

 

Not saying thats it for sure but 40,000 miles may be a contributing factor since guys mention getting better miles when the engine breaks in.....which could take up to about 75,000 miles. The only other thing I can think of "if" you've tried everything already mentioned, is the auto. Sometimes you can be loosing some mileage from torque converter slippage or band slippage but I'd think that a tranny temp gauge would let you know thats happening by indicating excess heat.

 

Thanks for the information....I guess it's possible that it could be problem with the transmission....The fluid always seems to stay at pretty low temperature.....I don't think I've even seen it get over 160 lately....I'm sure it will start to warm up with summer getting here in the south....It does have pretty low miles on it still....I guess it still does need some breaking in.....

Also, I've been trusting that overhead console that shows the mileage.....It's possible the thing could be wrong.....Truck runs really well though so I guess I shouldn't be too concerned about it.....

 

it's one of the sensors that is towards the very back drivers side of the engine on a 24V.....it's not the easiest thing to get to....look sort of behind the fuel filter canister & just a little further back on the engine.....i found that it helps to have a socket wrench with deep socket & extension to reach it.....it seems the only way to get too it is from the top....

 

Never trust the overhead display. Even stock, guys say that theirs isn't right and any HP add ons will make it even more inaccurate. Just divide the total miles driven since the last fill up by the fuel volume at next fill up. If your tires are larger than stock then you'll have to figure that percentage too or use a GPS to keep track of your miles driven. I say that because its amazing how wrong some people try to calculate their mileage.