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Poor Gas Mileage

Old 06-25-2013, 10:47 AM
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Default Poor Gas Mileage

I have a 1997 Civic EX Automatic. 176000 miles. I currently get 24 mpg city 31 mpg hwy. I read that it is suppose to be 30 mpg city and 40 mpg hwy. I have only owned the car for a couple months. The head gasket was replaced before I bought it. The head was rebuilt as well. I have replaced the fuel filter, Cap, rotor, and wires. I have put a can of seafoam through. No check engine light. The plugs were replaced at the same time at the head gasket. I have been driving very conservatively. I use 91 octane fuel. I ran 85 and that caused pinging. I talked to a guy at Honda and he suggested that maybe my valves need to be adjusted. My fuel gauge does not work. I dunno if that could be tied to a fuel pump issue. I do know that when I hit 3000 rpm i have a boost in power. I figure that is where the power band is. This is my first car I have ever owned. I have crossed over from Chevy V8's.

Any ideas or recommendations would be appreciated.

I also live at 4500 ft. I also know that this new gas that is up to 10% ethanol can cause a loss of mpg, but not this much.

Last edited by PaintballingPyro; 06-25-2013 at 11:30 AM.
Old 06-25-2013, 11:34 AM
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Forget it. I figured my problem out. I was looking out a 5 speeds mpg instead of automatic. I havent figured out how to delete my thread.
Old 06-25-2013, 02:40 PM
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Check your ignition timing anyway though. Properly tuned, the car should not ping on regular 85 - 87 octane gas (Do not use E85 of course!). If it really doesn't like 85, you can try mixing regular and premium gas in the tank to save some money. This gives you an octane proportionally between the two. For example 1/3 91 with 2/3 85 is an effective octane of 87.

Last edited by mk378; 06-25-2013 at 02:48 PM.
Old 06-25-2013, 06:10 PM
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Originally Posted by PaintballingPyro View Post
Forget it. I figured my problem out. I was looking out a 5 speeds mpg instead of automatic. I havent figured out how to delete my thread.
Thanks for the feedback, I do not think there is a means of deleting a thread unless you ask the moderator. You could have just let it slip by and we would be none the wiser, but you didn't . Good on you.

We have a 2007 1800cc 5 speed and we get about 40-42 Miles per Imperial Gallon(about 32 per USG) on the highway at about 60 MPH.

Last edited by civic2001; 06-25-2013 at 06:13 PM.
Old 06-26-2013, 10:07 AM
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I can close the thread, but I will not delete it since it can help others possibly. We try to reserve the "delete thread button" only for people who violate forum rules. OP, PM me if you need any help.
Old 11-29-2016, 08:19 PM
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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.
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