Poor Gas Mileage Unsolved - Page 2 - HondaCivicForum.com

Mechanical Problems & Technical Chat If you've got a problem you just can't figure out, a noise you can't diagnose, or a check engine light that won't go away, ask about it here!

Poor Gas Mileage Unsolved

Old 11-29-2016, 08:53 PM
Junior Member
Join Date: Dec 2014
Posts: 3

My vx was getting max highway about 48, average about 43 hwy, and city was about 33mpg.

I did all the other things everyone else did and still no improvement until I did the following:

Check the fuel pressure like the honda service manual says. My testing found it to be below spec.
I replaced the fuel filter and the pressure went up a little on one test but was still low on the other test(having to do with the vacuum line on the fuel regulator).
The test said that I should test the regulator, and if that was working it was the Fuel pump that was the problem. Which was what I did.

I replaced the Fuel Pump and the two pressure tests passed!
It ran amazingly different, but still had a tiny "miss" it seemed like, which was reduce quite a bit from what it was doing.

I decided to replace the Fuel Pressure Regulator just to make sure. (ebay $15)
The MPG went up dramatically with these fixes.

But, it was still feeling like the motor was off a little. So I checked the timing and it was off quite a few degrees! Must be the new pump and stuff affected the way it was firing and timing.

After setting the timing it ran perfect! No "missing", no hesitation, lots of power, smoother, quicker, 70 and even 80MPG on the highway on certain straight stretches.

I drove from Lake Charles LA to Tallahassee Florida and with the MPGUINO calibrated I got 61 MPG going 55-63MPH. That was a tank average after about 474 miles. The fillup said I got 59.7MPG

So Recap;
New O2 Sensor(NTK), new ntk plugs or E3 plugs, new cap/rotor, distributor, wires, cat convertor never got it above the 48-52mpg average for hwy.

A new fuel pump and screen, fuel filter, and fuel regulator, then re-setting the timing to proper 16 Deg BTDC(?) fixed all the problems of:
poor fuel economy, poor acceleration, poor power, poor smooth idling when it got hot, poor morning starts requiring me to try starting the car twice before it fired.

I can not tell you how freaking awesome this car runs now! It really amazing. It runs like it was brand new.

Oh, also add MotorKote to the engine oil to reduce friction. This product is amazing. It makes the surface tension of the metal tighter thereby reducing friction. Other additives dont do this, except a product called Militec(?).

Key words: How to get better MPG from honda civic VX?
My vx MPG sucks.
My civic vx wont start the first time, but will the second time i try to start.
My civic vx is missing at highway speeds.
My civic vx is not getting good mileage mpg need to increase.
My civic vx has poor acceleration weak power poor idle wont idle good.

I hope this helps people. It took me a few years and no one on the forums had solutions for any VX owners with these problems that solved it. This one works!!

Let me know if it helps you.
Related Topics
Thread Starter
Last Post
Mechanical Problems & Technical Chat
10-10-2011 10:22 AM
ECU Tuning & Fuel Management
02-03-2008 08:03 AM
Mechanical Problems & Technical Chat
01-29-2008 10:44 PM
Mechanical Problems & Technical Chat
02-14-2007 09:21 PM
Mechanical Problems & Technical Chat
01-31-2007 12:56 AM

Thread Tools
Search this Thread
Quick Reply: Poor Gas Mileage Unsolved

Featured Sponsors

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.