I'll also mention another cause of low MPGs, wheel alignment. Misaligned wheels can cause a MPG drop as well due to increased rolling resistance.
The Italian Tune-Up is also a great thing!
I too just bought a Fit as well. Mine's a 2007 AT Sport with 68K miles and I love this little thing! Great MPGs and even with the AT it's peppy and eager to take off from a light.
I changed the oil to Kirkland 0W-20 and put 3 caps full of Lucas Complete Engine Treatment in the oil and dumped the rest in the tank. I use Napa Gold filters.
The oil is staying very clean and my MPGs are about 31MPG around town and 35 to 37 highway.

One more thing... on the coolant temperature question - I use a ScanGuage OBDII and one of the readings is coolant temp- mine stays at about 172 deg F. The little blue light goes out at right around 100 deg F. A cold engine definitely will use lots more gas.

Every fraction of an improvement add up over time... Good luck!

 

FWIW, my L13A GD1's fuel economy seems to have improved about 15% after a valve adjustment, but I also cleaned out the EGR passages, replaced the PCV valve and grommet, and had the injectors cleaned while I was in there, so I wouldn't draw any strong conclusions!

Half of the valves had lash greater than spec, and the engine runs noticeably smoother and quieter now. Still showing LTFT of -5..-7%, as it was before the aforementioned work.

The EGR passages had a lot of carbon buildup but not a total blockage (the port for cylinder 3 was the worst).

 

You got a how-to or a diagram for this?

Thanks.

 

I've been trying to diagnose my low MPG.
I do a lot of short city driving, but I have to fill up after 250 miles or less.
However, I always use "sport" mode and paddle shift which I'm certain affects MPG.
I'm still considering doing a valve adjustment as I've tried/changed almost everything else.

 

Have you calculated your actual mileage by dividing the miles driven by the gallons filled? The Fit has a really small gas tank.

That said, the old Fit's don't get modern fuel economy. If you do the math and are getting 28-32, you are doing great.

 

My last fuel stop was 8.747 gallons at 230 miles (I forget the actual trip mileage).
I've been only using Shell 93 Octane as it's a minor, almost negligible, performance increase.
I'm doing an oil change today and using 0w20 (Honda's Full Synthetic), which might help from what I've read, but it'll be minor as well.

At my next fuel stop, I want to try my local Wawa's ethanol free gas (89 Octane?) to compare.

 

Hmm. That works out to 26mpg. That's not so great unless you're spending significant time idling in traffic.

I will say that, when it comes to the GD and GE Fit, 90% of problems can be solved with NGK or Denso Iridium spark plugs, Denso or Hitachi ignition coils, and/or a valve adjustment.

You'll see better fuel mileage with the ethanol free fuel since it has a higher energy content, but it won't be a huge difference. Overall, it's hard to beat Shell 93. It's a really good fuel.

 

I replaced my spark plugs last year with Denso IK22s, if I remember correctly. That could be another factor why my MPG is lower.
I also replaced my coil packs with NGKs. They may not have "needed" to be changed, but I replaced them for not matching.

I don't idle too much unless there's a lot of traffic which is rare. Most of my idling would be waiting in a drive-thru line for a coffee.
A valve adjustment is my next consideration, but the dealer quoted an absurd price of $681.39 yesterday. Either I'll wait and get other quotes or buy the "feeler" gauges and do it myself eventually.
I also found out that my front end tie rods need to be replaced too.

 

I fueled up with Wawa 89 (Ethanol Free) - 8.218 Gallons | 228 Miles.
Time to see how it compares to Shell 93 fuel economy wise.

By the way, is the 07 Fit's fuel tank capacity 10.8 gallons?

 

yeah 10.8 gallons. I average about 25-29 MPG depending on NYC traffic, but its pretty consistent in that range.

 

i just got my fit about a mouth ago!! it had 225 690 miles on it. it ran good but on cold mornings on take off it would want to choke down but when it warmed up it was fine changed air filter
did not help talk to a few people that said try adjusting the valves i did that and now she runs like a top !!!! still only getting bout 33 miles to the gallon>>>
5 speed HKS HI-POWER EXHAUST cut off resonator 17in wheels 205/40/17 tires i sure all this has a factor in to the miles i'm getting