Improving Gas Mileage

[Theos92VR4]

I calculated tonight and I get 25 mpg combined city and highway. With an intake and catback exhaust.

[Sarthos]

That discussion didn't involve research. or even an excess of 10 posts!

[Honderacc_91]

I never have a full tank of gas to know how much mpg's I have, I forgot the calculation for it anyways, I was told is to be a full tank..

I have a bad 02. So I no my mpg's r low I can even smell the gas, once that's fixed, I would like to change the fuel filter.

I drive like a granny since I have a 4door now.

If im smelling gas in the cab what is wrong? I know theres prolly a few holes im my exhaust (going to upgrade soon) any thoughts.... Thanx

[bcjammerx]

you can chip an ecu for it...coulda sworn a member here had a turbo'd car and he and managed to tune it to getting 30mpg


any hoo you could chip your ecu and play with it, as long as your maint. has been kept up to date you should be able to...our cars seem to run a tad rich anyway



btw I get 28 mixed city/highway driving in the summer...in the winter it goes down to 27...I got 30 all interstate driving a couple times.

[deevergote]

The PT3/PT6 are actually tuned quite well, unlike the H22's P13 that always seems to run pig-rich. ECU tuning is not necessary, at least not right away.

The first step to high MPG is a healthy motor. Make sure the engine is in good condition (no leaks, good compression.) Then be sure all electrical connections and grounds are clean and tight. Replace all "tune up" components... distributor cap, rotor, plugs, wires... Use parts from Honda to ensure they're working exactly as they should be (the Sumitomo wires that Honda uses are actually some of the very best wires you can get... better than the gimmicky shit on the market.)
Make sure your engine is running clean, quality oil (really expensive stuff is not necessary, but won't hurt... just don't use the cheapest oil you can find.)
Make sure your transmission is filled with fresh Honda fluid. Manual transmissons also work well with GM Synchromesh fluid. All these things should be done anyway... not just in an effort to achieve high MPG.
Make sure all airflow components are healthy... air filter, catalytic converter, exhaust system and muffler. Make sure there are no leaks, and the filter is clean.
Clean your fuel injectors. Do some research on which product works best (third party research, not the manufacturer's claims.) Or have them cleaned professionally.
Make sure all sensors and emissions components are completely functional. Clean and replace as necessary.

Next, we look at the stuff that keeps your car on the road:
Tires. For the best MPG, you don't want a wide wheel, or sticky sport tires. Here's a place where cheap economy tires will actually help you! Cheaper all-season tires will be made of a fairly hard rubber compound. If the tire is not made of a sticky rubber, it is offering less resistance while rolling. Less resistance means better gas mileage. Getting a skinnier tire will help as well. If you have the choice between a 185 width and a 195 width, get the 185. Handling will suffer a bit, but MPG will increase. Make sure the tires are at the proper PSI at all times.

Wheels. Lighter wheels offer less unsprung weight... less for the engine to move. However, many light wheels are also wider. A wide wheel takes a wide tire, which will decrease MPG more than the lower weight will increase it. Your best bet is to find the lightest set of stock alloys possible.

Suspension. Make sure your suspension is healthy. Blown shocks, worn bushings, etc... these things will cause uneven tire wear, wheelspin on rough pavement, and extra movement that you don't need. Aside from being a major safety concern, these things will decrease MPG by a bit. Make sure your suspension is new. If MPG is the greatest concern, then stock or stock replacement parts are your best bet.

Alignment and wheel bearings. If your wheels aren't properly aligned the tires are dragging needlessly. Get an alignment, and eliminate that extra strain. Poorly aligned wheels will cause a noticeable decrease in MPG... and you'll also be spending money on tires more frequently than you need to.
A dragging wheel bearing will also decrease MPG. Again, this is something that should be replaced if it is going bad anyway.

Brakes. Make sure your brakes are healthy. If your brakes are dragging, again, you will lose MPG... and wear will increase. Make sure that they are in proper working condition, and can stop the car smoothly.


Next, your driving habits.
Generally, I try to keep my RPM no lower than 2,000, and no higher than 3,000 when trying to get good gas mileage. Too low will be lugging the engine... causing it to work harder than it should. Too high, obviously burns more fuel. 2-3k is a reasonable operating range.
Don't accelerate more quickly than you have to. Take it slow, make it smooth.
When braking, think ahead. Don't slam on the brakes and screech to a complete stop. If you see a light turn red 2 blocks away, put the car in neutral and coast... braking lightly. If you can time it well, the light will change before you have to stop. Accelerating from a 10mph roll takes less gas than accelerating from a complete stop.
Driving with the windows down increases drag... so keep em up if you can bear it.

Finally, the only modification really necessary: Weight.
The less your car weighs, the less energy it takes to move it.
If you have a bumpin system in the trunk... put it in your basement.
Replace your spare tire with a can of Fix A Flat. Get a AAA membership just to be safe.
Don't frequently have passengers? Remove that heavy front passenger seat. The rear seats don't weigh very much, but you could pull them too, if you don't mind some extra road noise.
Do you weigh 400lbs? Put down the twinkie and pick up a rice cake.
If you really wanted to go nuts, you could remove your AC system, and replace your battery with a smaller, lighter one,



Do these things, and your MPG will be as good as it can get without doing any serious modifications to your car.

[cb7k-9 unit]

i get about 352 miles to a full tank of gas, with one bad motor mount. normally i shift between 2x and 3x rpm, on 185 tires

[bcjammerx]

well I was giving ideas aside from the obvious and those ideas already discussed to death.

but deev is right...bad water temp and o2 sensors, dirty conventional oil, low tire pressure...all that routine maint. stuff too can all wreck mpg's but nothing does so as much as your right foot.

[1BAD1990CB7]

Deev is right, but one thing I have not seen anyone say that ethanol free gas will help too. It's about 4 cents more per gallon. Now I am getting about 28 mpg up from 26 when I didn't use it. Anything is worth a try.

[deevergote]

Many places don't offer ethanol-free gas. I don't think I've ever seen the option around here. If it's an option, then it's definitely worth a try.

[mtnbikaah]

Gas in Massachusetts has a MINIMUM of 10% ethanol (or is it 15%) There is no getting around it here.

[GeoffM]

Gas in Massachusetts has a MINIMUM of 10% ethanol (or is it 15%) There is no getting around it here.

10% here. I thought it was a federal law.

[1BAD1990CB7]

Gas in Massachusetts has a MINIMUM of 10% ethanol (or is it 15%) There is no getting around it here.

Marijuana is also a illegal by federal law but not in some states. You can get Ethanol free gas all over SC, I have 4 station with in 2 miles of my house.

[bcjammerx]

Marijuana is also a illegal by federal law but not in some states. You can get Ethanol free gas all over SC, I have 4 station with in 2 miles of my house.

wtf? Never had a dealer try to sell me "100% pure gas" big difference between pOT and gas man lol I'de like to meet your dealer...if they have their own refinery...doin something right lol

When tx started doing the 10% there were a few (even in my deep country area) that made a point of not having it...I can't speak as to the legality of it...wasn't aware non-mixed was now "illegal" but even those places that boasted no eth. are now 10%. but again they were so few and far between the extra 1mpg I would get using straight gas was lost traveling the extra distance to get it.

*blows raspberry*
it's ALL 10% around here now...course if the gas/oil companies no longer sell straight gas your local gas store can't buy it. and since it drops mpg's a bit I'msure they're loving' it lol

[bcjammerx]

oh btw...best way to improve mpg's don't go over 60mph...65 on interstate. You don't lose any time really (unless on LOONG trips) and you really drop the amount of resistance from the wind.

[GhostAccord]

Around here the Premium grade of gas does not have ethanol added. However as mentioned in another thread discussing octane rating. A higher octane isn't always best for the performance and/or efficiency of your car.

Complete combustion is a good way of gaining MPG. Tune up! A complete ignition system overhaul, valve adjustment, check your timing, a new air filter, and clean fuel injectors will all aid in gaining a few MPG in the long run. Best one in my book is to keep your foot off the floor and try and keep the RPMs down.