First I did do a seach, and I read 50+ pages of threads before posting this. I'm new to this forum but not forums in general.

I just got my 2007 H3 Adventure delivered last week. 47,000 miles, auto trans. It is leveled with Nitto 35 terra grapplers. Air filter is a K&N cone filter inside the stock airbox.

My first tank netted me 11.7MPG. I live in SC (Low Country = no hills). I commute 30 miles each way 10miles @ 50mph, 18miles @60mph, and two miles in "city".

I realize the #1 factor is the drivers right foot. So for a frame of reference the car I ditched for the H3 was a 2011 Camaro 2SS lightly modded (460bhp) my lifetime average was 22.1 and the last 13K miles was just ove 23mpg. I drive very economically, and have a commute that while long is at very good speeds for fuel economy with very few stop lights along the way.

Before I picked up my H3 I read many of the post here to make sure I wasn't putting myself into too bad of a situation. I was expecting to see 15-16 combined with my current config and driving pattern.

My question is what could be causing such poor economy?

and

What cost efficent maintenance/modifications have been proven to be viable by the crowd? Clean/replace the MAF & O2 sensors? Clean the throtle body? Throttle body spacer? Plugs & wires?

Thanks for the help.

 

One thing I neglected in OP. It does have a magnaflow cat back exhaust. there is a roughly one foot long cylinder down stream of the cat (under the rear seat area) that leads to a muffler with two tail pipes.

Thanks

 

Are you taking into consideration that you have 35s when you calculate your mileage (you should be adding miles to your calculations) and they are some of the heaviest 35s out there? Do you have aftermarket rims also? Unsprung weight kills mileage and depending on what tire size came stock you will have to do the math on the percentage difference to add to your mileage. I don't know of many I5s with heavy 35s getting better than 14 combined.

Your other thread about the temp of the HVAC system can be found by doing a search. Either the resister pack is fried or you need to recalibrate the blend doors.

 

Agree with last post tires and wheels..

 

The first question was already answered, so I'll work on the second.

Clean the MAF with MAF cleaner, follow the instructions on the can (there are threads here as well).

If you have no CEL or code, leave the O2 sensors alone, 47K miles is not replace territory yet. Check for any stored code.

Clean the TB with TB cleaner, same deal, follow instructions and there are threads here on that.

TB Spacers are paperweights, they do nothing.

Your I5 has no plug wires, coil on plug packs instead, no maintenance item.

47K is way too soon for plug change if you have no other symptom.

You can look at an intake, PCMforless tune and/or Efan conversion, and a port polished TB.

I have an 07 with the above mods, 305 MTZs, BA winch Bumper, Roc Doc Rear Axle Skidz, RR Rock Rails .... etc (lots of sprung weight), and get 18 on average, and can do better on all Hwy.

 

Thanks for the help guys.

 

So what is your tire size corrected MPG? You also never mentioned if you have aftermarket rims. If you do what size and brand/model.

 

Yes the wheels are aftermarket. 20".

After the first full tank it looks like a 5.67% correction is required for accurate numbers. (odometer miles X 1.0567) divided by # gallons requried to refill the tank is just under 12.5. Hopefully I'll get used to driving it & can nurse that to 14...

Thanks again for the help.