K here goes only getting 225 miles on a full tank of gas on my 08 h3 i5 with 105,000 miles...which i think is around only 5 mpg..its been like this for over a year which i thought was normal for a h3 until i decided to read more on this forum..

Im all stock minus the brush guard..i have a airdoc intake , k&n air filter , tires are all filled proper ,oem brand new plugs which ive changed twice thinking that would help and i clean my throttle body every month.

I have no check engine lights or problems..minus i get one for some reason if i put on my air,heat or blower on facing the driver body..and that throws a misfire code ..so i just leave it on defrost that way i never ever get it unless i switch to that again and it erases itself after a few starts and drives...i have water always coming out of a pipe in my engine compartment i dont think its the sunroof drain pipe because waters always coming out and it hasnt rained in 3 months ...and iam missing the small stainless gas flap that lets the gas hose go into the tank ...im at a loss here this gas milege is insane..only thing i can think of is im not running on all 5 cylinders?...i have good power drives good and isnt sluggish at all really really weird any help please..thanks

 

The fuel tank on an H3 is 23 gallons which would be giving you about 10mpg if you were running the tank bone-dry which I doubt you are. If you are refilling using about 19-20 gallons at fill, then you are currently getting about 11-12 mpg which is still below the average for the H3.

 

You did not mention cleaning your MAF. Get some MAF cleaner, follow the directions. Basically you remove the retaining screws, pull the MAF out of the air filter box outlet, spray it off real good, then carefully put it back. DO NOT TOUCH the MAF sensor end.

When was the last time you did brakes? Check that you do not have a caliper dragging a pad against a rotor. Might be worth pulling off the wheels and doing a thorough inspection, see if one set of pads is worn substantially more than the rest. Look for corrosion around any caliper piston, the pad pins etc...

 

Sorry doc i also clean the maf when i do the throttle body every month..i have check as much as i can and i have crossed drilled and slotted rotors with new pads thst were put on about a month ago.all are in great condition still..

 

The constant water leak is the fact that you have the defrost on! The defrost engages the A/C compressor to blow dryer air on the windshield. Thus the water dripping just like when you run the A/C.

That could also have a great effect on your MPG with the A/C compressor dragging and robbing power from your I5.

Turn it to the floor with the A/C off and see if it still leaks.

There is a fix on here for the blower motor resistor which may help you with the light.

 

What they said, and also when you clean the throttle body are you unbolting it and taking it out and cleaning both sides?

 

I think you are messing with it too much.

Cleaning throttle body every months Why? Where did you get that from??

Mine is an 07 model and I have never cleaned it and it's fine.

Then you say your H3 is totally stock and proceed to list a string of modifications. stock means as it left the factory.

Running the air con 24/7 would not help fuel economy, I only run mine when I need it.

Turn air con off and see how you go. Plus I think your calculations are way off as well.

 

How much sitting and idling do you do with it? Like to drive fast around town? Any dents in the fuel tank skid? Do you have any intake air leaks?

 

Aussie, you have to clean the T.B. We do ours at least once a year, or about 20,000 miles. And yes, once a month is way overkill. Not necessary

 

Might check it next time I service the truck, can't really see the point when it's running fine, but I will check