All Fits have the same aerodynamic drag and drivetrain loss, apples to apples depending on model and tranny so lets focus on wheel/tire combos... A larger wheel/tire has more weight to spin, more rolling friction, more wind resistance. A smaller wheel/tire has less of these forces but a slightly higher engine RPM at any given speed. All said and done, smaller wheel/tires do get better milage.

 

At 63K or so my 02 sensors failed, normal. I took the opportunity to adjust the valves and install new spark plugs. OEM plugs were NGK Iridium and one of them, according to color on the thread pattern, had not been properly torqued at Suzuka and was probably leaking. I replaced them with Denso Long-Life Iridiums, my personal favorite, gapped and torqued perfectly, and I took all day getting the valve adjustment as perfect as I could. They were not off dangerously, but were off. The result was 2 mpg better than the car had EVER gotten before. It impressed upon me the fact that, despite my gladness that the car was assembled at Suzuka and not in Ohio, Honda factory standards are not what they used to be. I run 0W-30 Mobil 1 in summer and 0W-20 Mobil 1 in winter. I use Chevron Supreme 90 Octane all year round. I also switched from OEM tire size in summer (Nokian WR-G2) to 195-60-15 Nokian Hakkapeliita 7 studded tires for winter and am averging about 4 mpg less in winter.

I would strongly recommend that you replace your 02 sensors; if I had it to do over I would order Denso 02 sensors from Amazon.com (I used OEM NTK sensors) and I would replace your plugs and adjust your valves. Then you will know what your car can do.

 

My mileage has fallen off a cliff lately...usually got 35+ just puttering around town [and 38-40 shooting across the highway], but since late October it's been on the decline. A new air filter during safety inspection made it even worse. My last tank was sub-30 average...I'm used to seeing 190-200 by half tank, and this last time by the Audrey II ["Feed Me"] came on at 260.

My baby's an '07 Sport Manual, 63,000 miles; Dad said he heard a slight miss when I was up for Christmas, and it has been down on power. The dealer said it's nowhere near time for plugs [and the maintenance minder is 9,000 miles slow...asked for the 50k at 59k], and would like to do 60-120 minutes of diagnostics before they even think about turning a wrench.

I'm neither an expert nor a stranger to turning wrenches...my mind was blown to see these little things have coil-on-plug, but after some quick browsing and seeing talk of clogged O2s [On my other car, that threw a CEL...so that may not be it] and adjusting the valves, I want to make sure I'm not over my head and making matters worse by doing what I've done with misbehaving cars for the past 15 years.

Where do I start, is the dealer trying to rip me off? Thanks ahead of time!

 

You got it right. Making that poor little engine push them big old heavy tires around takes more work. Thanks tho for the comparison.

 

winter weather absolutely...wait till summer comes.. all mpg rising

 

1 to 2 hours for diagnosticsis as rip=off as it gets. Buy a OBDII tester for $55 and do your own checks.
There no such thing as a time for replacing plugs or coils; anytime after 30k miles they may need to be replaced. The least yiou can do is pull the plugs and clean and re-gap them. BTW, the reason for the coil/plug combo is reduced manufacturing costs especially with electronics.
And yes you ought to set valve clearances, even if its just measuring that they are i spec, every 30k miles unliess you are a racer, then more often.
As for mpg make sure its not your gas or your injecors; add a bottle of injector cleaner now and mabe a second then a bottle every month. Injector cleaner free of alcohol is available from WallyWorld for about a buck fifty. fequent maintenance am not free nor unnecessary , no matter what the marleting troops tell you.
Its like that old ad 'pay a little once in a while or pay a lot much later'.
cheers.

 

Here where all we get, usually, is colder weather, my Fit doesn't change much in mpg, stays 28-30 around town and 35-40 on interstate and unless you have snow and ice it shouldn't be much different unless you do a lot of short trips..

 

Thanks for the heads-up! Between asking here [and later getting impatient, starting my own thread], I've gotten a lot of info on the GD's quirks and maintenance requirements. This is my first winter with it [bought it in May], and was more than a little shocked to see my 34-36 reliably puttering around town turn into 28-30. I'm hearing quite a bit of 'It doesn't like the cold', along with the common theme of the valves and plugs not being nearly as durable as Honda wants them to be.

Good call on the injectors; it had a bottle of the 'use every 1500 miles strength' stuff two tanks ago...I may give it another shot here soon.

I'm still hoping the weather cooperates...I'm neither confident enough, equipped enough, nor brave enough to run the valves in a snowy parking lot (the joys of being a renter), but if I can get a decently warm day can at least pull the plugs to have a look at them. Do you know the gap spec, by chance?

I figured the coil-on-plug would've been so they could lower the power draw of running the engine...sending the kind of voltage a plug does across a foot or more of wire has to have some serious losses to the ohms of the wires, which only get worse as the wires age. Either way, a peppy little economy car is the last place I expected to find coil on plug stock...though cool as it is, replacing those packs looks like it's going to be painful, at almost $150 each for genuine imitations [Duralast].

 

sounds like you need to start shopping at rockauto.com..

 

is the most common thing in winter to get less mpg...

 

Welcome to the freakworld!! It is the most common thing.

 

any update with mpg after tune up.....im seeing around 260 to the tank

 

My MPG had also been on a gradual decline and I had always figured it was because of my modifications, but a valve adjustment brought it back.

For 6 months after I installed a new flywheel, I was never able to break 31.9 MPG, no matter what mix of city/hwy I drove or how much I grannied the car. 31.9 was literally the best MPG I could get.

After I broke 100k miles, I changed the spark plugs. No difference whatsoever, including fuel economy. Still couldn't break 31.9 MPG. I just wanted to see a freaking 32. I really thought it was all because of my flywheel sapping away my highway mpg.

About 4,000 miles later I adjusted the valves. At my next fill-up, I was rocking 33 MPG, and the tank wasn't even full when I did the valve adjustment. The engine also sounded and ran a lot smoother/stronger immediately after the valve adjustment, especially when cold-start idling and at high RPM.

At the following fill-up I had achieved 35.9 MPG. My highest mark since who knows when? Literally years ago.

Now I'm consistently getting 35 MPG and higher in mixed city/hwy, roughly 30 more miles per fill up. That's an increase from ~280 miles/tank to ~310 miles/tank if you aren't good at math. And I haven't even grannied the car yet. It's a substantial increase considering I could never get to 32 MPG for 4,000 miles, or 13 tanks.

Valve adjustments are the bomb.

 

I've noticed that periodic valve adjustment is recommended. Is this a difficult thing to do for a non-technical- savvy person such as myself?

 

if anyone has a how to,,,for the vavles...ive done on other cars ..
just want to know the specs....

 

Here's one: https://www.fitfreak.net/forums/fit-...clearance.html

 

It's not difficult if you've had some kind of experience in DIY automotive wrenching, whether it be changing all your fluids, rotating tires, changing brake rotors/pads, and/or installing an intake/exhaust. Nothing crazy really.

You will have to remove some parts just to get to the valves: part of the intake manifold, the airbox, some sensors, the valve cover, and a few other things I don't remember right away. There's several hoses to pull too.

Each individual step is completely doable in my opinion (but the same is true for any automotive work if you really think about it). It's up to you whether or not you're comfortable stringing all of them together into a relatively time-consuming job.

I highly recommend using a calibrated torque wrench for this job. Don't try to torque these parts by feel.

 

what u guys think about an intake or making the stock flow alil better......

 

Your advice is well taken. It's not something I have to do right away, since my gas mileage is still great, but it's definitely on my 'to-do' list in the future. Plus I gotta make sure I have at least two consecutive days off from work. No work = no pay. No pay = no toys for my Fit.

 

Last time I had horrible gas mileage my tire pressure was extremely low. Also, as a gas saving tip. I took out my back seats and am getting about 40-43 HWY with hypermiling and about 36-37 city by hypermiling. I also removed my stock header and put a megan header on and I think that helped a bit. The quicker the air can get out the easier your engine has to work, theoretically raising mileage.