Gas mileage sucks! Pls help!!!
 

So i purchased my pre owned 2009 Honda fit sport about a year ago. ive done the oil change, changed both cabin and air filters, and transmission fluids are leveled and good to go. currently only getting 17 city and 20 highway. what else should i be doing?

So many possibilities ... No other symptoms?

Easy stuff you could do:
Check brakes, wheel bearings, make sure nothing is binding (e brake too)
Check for codes. I'm assuming your CEL is off, but you know, sometimes they somehow "come unplugged" before a used car sale

How many miles on car, could you need valves adjusted or plugs?

Might check that your spark plugs have not come loose. This is a common problem with the Fit. There are a few recent threads worth studying.

Also some spring cleaning might help. Some items sumarised in items 10 and 11 below.

https://www.fitfreak.net/forums/2nd-...fit-sport.html

Are you calculating this by hand? If so how?

Good point GolNat. I always get fooled when someone quotes gas mileage as then goes "well I put in $2 of gas then I drive 15 miles then I filled it to the top of the filler neck and ..." or some variant of that. Good to cross that off the list as a possibility :)

ok, brakes are good, bearings were done when I first got the car, ebrake seems good, isn’t engaged. No Check engine. I got the car with 118k, currently at 122k. Valves and plugs I need to check.

good question, not by hand but by mpg gauge per trip. I reset it after every fill up. I always fill up and empty out to ensure accuracy and to make sure I’m always cycling thru the gas.

check out my reply to GoNal. I also did a systems check with my 2nd to last fill up and have used 93 oct. in those last two fill ups.
https://cimg1.ibsrv.net/gimg/www.fit...e55bacb39.jpeg

move out of the Bronx. stop and go traffic kills mpgs on a GE8.

By that much though?!?

I mean I have never traveled in real city traffic but I would expect the worst to be in the mid 20's city. The highway mileage should be way higher then 20 but how many of those miles are highway? Only 30 then that's not enough.

I always got worse MPG on 93. Also get on the highway and reset your MPG/trip meter. Once on the highway see where the meter reads. I would expect 30's at that point without any stop and go traffic.

Was the MPG higher when you first bought it a year ago or is this a new development?

I just had similar gas mileage on my Wifes 2011 Honda Fit at 92k miles. 17 city/24 highway. (AWFUL)

I now get 28mpg city 35.7MPG highway.

Ill tell you everything Ive done so far to achieve this in the order that I did it.

I did all of this work for two reasons:

1. gain MPG
2. Eliminate annoying knocking sound in engine after it was hot and idling.

Total time: 1.5 months
Ordered parts I needed from Amazon/ RockAuto
Still in progress.

Just did my ATF trans fluid today and only have the motor mounts to replace and the back struts.

(Mounts worn from wreck last year)

I will only list things that you will potentially have to buy, not bolt sizes, etc.


1. Cleaned Throttle body. Had a lot of carbon buildup on it. Used Throttle Body Cleaner and a shop towel. (ONLY sprayed on the towel, not in the throttle itself.)

Parts/Supplies needed: Throttle Body Cleaner, shop towel. *PCM idle learn procedure recommended after this cleaning is completed.


2. Cleaned EGR port, inside and out (avoiding electrical connecter). Made sure valve opens and closes freely by hand. It was dirty as hell by the way. Also cleaned the EGR exhaust pipe, intake manifold passages, and replaced all gaskets.

Parts/Supplies needed: EGR gasket, EGR pipe gaskets (1 upper, 1 lower) (manifold gasket was good)

3. Replaced Spark plugs and Coil Packs, gapped new set to 0.40 with Hitachi OEM Coils. Dabbed a dollop of grease on the seramic boots and a little on the inside of the boot. (Avoid grease contact with the wire) did not grease plugs as was not necessary.

Parts/Supplies needed: 4 Hitachi Coil Packs, 4 NGK iridium spark plugs (Verify gap is correctly set before installing) , spark plug socket with rubber boot for extraction, torque wrench. (Optional, but recommended for torquing plugs to 20ft lbs.) Dialectic grease

4. Valve Adjustment. This was the most time consuming thing that I did, considering I had to complete this twice because I FD up the first time around by having everytying too loose.

Remove battery, airbox, throttle body and intake manifold plenum (one piece), and the valve cover. Adjusted valves to factory specifications.

0.006-0.008 for intake valves
0.011-0.012 for exhaust.

Found that the intakes were loose, and the exhaust were all too tight. Adjusted accordingly.

Parts/Supplies needed: computer and internet with access to fitfreak.com (you guys carried me through this, thanks again!)

Valve cover gasket, hondabond 4, angled feeler guages, valve adjustment tool (optional, highly recommended)

****this eliminated my engine knock****

5. ATF Transmission fluid/filter change (noob.method)
Literally just changed the filter, drained from drain bolt, cleaned plug, put 3.2Q of new Honda DW-1 fluid. Will repeat process again in a couple of weeks. (Minus changing filter)

Parts/Supplies needed: ATF Filter, 4 quarts of Honda Dw-1 ATF Fluid, ATF funnel.

I also replaced the cabin air filter, as well as the airbox filter, as well as ran some fuel injector cleaner.

*************

So after all of that, the car sounds great and like mentioned above, great gas milage.

Hope that helps, gives some insight.

Adjust valves and install a fresh set of iridium NGK or Denso plugs. Car is way overdue if never done.

Chuckd, after which change do you think things got better? Any improvement after plugs, or only after valves?

Fwiw, I do not think 17/20 is a normal range even for city traffic. Maybe if you are just sitting there and then doing sprints to the next stop. Highway, 30mpg should be the minimum you should accept, below that something is clearly off..My two cents

I got a little bump from each procedure, but the things that made the biggest difference seemed to be the valves, changing the airbox filter, and cleaning the egr port and passages.

My plugs and coils were in ridiculously good shape for 90k miles. I almost didnt replace.

https://cimg9.ibsrv.net/gimg/www.fit...2cdbbd0c8e.jpg
This the 'calculated' MPG on every fill up on my '11 Sport AT. Please note the variability in the blue line. It should be readily apparent that no two fill ups are the same and there has to be a myriad of reasons that aren't important right now. My point is that low MPG 'real' or the result of filling the gas tank to a different level than before can create the impression that the MPG has gotten better / worse.

I think part of the reason for my overall 'drift' to lower MPG is due to less highway miles versus local stop / go driving after a job change.

Anyway, please don't get hyper-focused on the result of one fill up calculation of MPG. Because it jumps around so much, I started a 'running average of 15 fill ups' to provide a smoother line (red) decrease the 'noise' in the data.

https://cimg9.ibsrv.net/gimg/www.fit...21d9593c4b.jpg

Although this is old, it does show you the relationship between the 'calculated' MPG and the "Dash Meter' MPG. There can be -3 to +4 MPG differences between them on any particular fill up but 'on average' they closely agree. Please note that this early 2018 shot covered 369 fill ups (data points), so it's got some credibility.

thanks will print this and make it my new check list.

Awesome. Let me know if you need any help!

https://cimg3.ibsrv.net/gimg/www.fit...61ccceaed5.jpg
This is another way to look at the MPG data per fill up. This is on 399 fill ups since new.

I just ran this bottle of cleaner also
 

I just ran this bottle through my car. Before the MPG gauge was reading 34ish. When I was running that tank it was reading 36/37. My first tank after I got up to 39.3. Bigger change than I thought it would be. 151k miles.