I've had my fit since 08. It has 93k miles on it and I've always taken good care of it. Around 85k it started running rough and I replaced the plugs and coils. It was still running rough so I took it to the local Honda Dealer (they suck) and they replaced my fuel injectors. For the last 10k miles or so, my mileage has dropped by about 6 MPG. I commute to work on a 2 lane highway at 60mph, which is usually the sweet spot for my car. Used to get 39mpg average almost every tank of gas. Now its always 33.

I really don't see why new fuel injectors would cause such a significant drop, but it started the first tank after the repair was done, and hasn't changed since. Any ideas?

 

Before you get deep in it make sure you're running properly inflated tires, not running wider than original tires, and no bolt on stuff outside like a roof rack. Then remember that mileage tanks in the winter time because of winter blends fuels and denser air.

After all of this is checked and you still don't see an improvement look into a valve lash tolerance job, which should be done at 100k anyway.

 

If you were cool with changing the plugs yourself I'd suggest gettin back in there and making sure all is well, maybe check out the injectors. it's still running rough, yeah? Like.. at idle, or high rpms? If it's clearly engine related I'd double-check the work done as.. this engine has yet to yield other issues per my experience and findings. Plugs losening. valve adjustment, fluid changes.

I'd be more interested in inspecting the other stuff. A bad alignment perhaps? Or brake replacement where they forgot the little springs.. it's all basic with this thing 😂 just works. I've nothing new to contribute!

 

+1 for a valve adjustment

 

Are you going off the Fit's instrumentation for MPG? There was a TSB to address the Fit's meter accuracy for 09 models (it reads 10-15% higher).

Maybe they updated yours?

https://www.fitfreak.net/forums/2nd-...ml#post1093161

 

I bet that's what happened. None of the normal stuff had changed (aka tires, tire pressure, where I was driving, season) But it happened after they replaced my fuel injectors. I bet they updated the meter. I was going by the electronic display and not calculating the mileage myself. Thanks for the information.

 

When service advisors write up a car they also run the VIN to see if there's any active recalls or service bulletins for the vehicle so it wouldn't surprise me if they did the update - that's a quarter of a hour for a tech. It would surprise me if they didn't tell you they did the update though. You could try calling and asking, but for what it's worth I'd start keeping track of it in a notebook. My Fit averages 20% higher MPG on the dash versus what I actually get too.

 

Listen to this guy (this is exactly what I was going to write)