Better Gas Mileage?

[cyclesucka]

I was looking for some ideas on improving the gas mileage on my '93 Accord EX. As of late, I have replaced the air filter, the spark plugs, and I have added a fuel injector cleaner to the gas tank. Not too long ago, I was only getting about 26 mpg, and that is unacceptable. I am now up to about 28 mpg. I want to see the mpg well above 30 if possible.

 

Input would be great. Thanks.

[James Matteu]

Tire pressure, you need to keep it maxed.

[CleanGSR]

I disagree about tire pressure. Maxing it will wear out your tires sooner (bald in the middle/tread left on outside). The cost savings of gas will be lost by having to purchase new tires sooner.

 

One big thing I"ve seen on a fuel mileage forum is to get a Hot Air Intake. These people rig it up like a Short Ram and somehow plumb hot air from the exhaust manifold area to the intake. They are seeing around 2-3 mpg increase from this mod and I'd imagine it's due to the ecu adding less fuel since the air is less dense when it's hotter. Of course this mod will gain mpg but lose hp.

[cyclesucka]

How much does that mod cost? How labor intensive is it? How much HP would I lose? I don't really care about a loss in HP, because I have a '93 Accord, and I am by no means racing the thing around town, but I don't want an astronomical drop in HP obviously.

[CleanGSR]

I don't know the cost but it if I remember correctly it was fairly cheap and the plumbing was done with the flexible dryer vent hose stuff (the aluminum stuff). I'll try to find the forum that I read that on and you can search for it there.

 

Don't know how much hp you'd lose and it shouldn't be very labor intensive at all.

 

Another thing that can help is a Home Depot front lip. You use a flexible but tough plastic (landscaping edger or something...not sure exactly what they use) and attach it to the front bumper with screws/rivets to make the front end lower. This will help prevent drag going under the car and improve aerodynamics to get better gas mileage. If you don't want to look weird then you could attack it under the bumper somehow so it's not as visible.

 

Also next time you get tires, get tires that are a little bigger than recommended. For example, I think your accord reccomends 195/60/15's. Try running 195/65 or 195/70. The larger tire will make each revolution that you travel take you farther at the same rpms. So when your engine and car thinks it's going 70mph you'll be going 75. Your mileage will look the same if you calculate it by the trip odometer vs. fillup but you will actually be going farther than before. Every 280 miles that your odometer shows you will have actually gone 300 miles.

 

So for the above scenario if it cost 10 to fill up at 280 miles then you'd be getting 28mpg (what you said you get now). With the extra travel you will have actually gone 300 miles even though the odometer shows 280 so your actual mileage would be 30mpg.

[Jeffro]

You need to change your driving style if you want to dramatically improve your mileage. Don't get me wrong, I realize it is difficult for most people to really have under control. Here's my story:

 

I have always been fairly consistently at 32 mpg driving to work (mostly highway). But about 2 weeks ago, I read about hypermiling and I became extremely intrigued. I thought, what would it hurt to try it out for a little while? So, I gave it a shot. I began keeping my speed down (at the speed limit mostly) and doing a lot of coasting in neutral down hills and anywhere else I could manage. I started coasting to stop lights and stop signs and anytime the speed dropped I'd shift to neutral and coast down to where I needed to be. The first week I tried it, I managed just under 35 mpg on what was left on my tank. I was thinking, "that's pretty cool, but is it worth it to keep working on it?" I figured I'd try it out on a complete tank. This past Tuesday I got my results: 15.622 gallons and (gasp) 610.1 miles. That's just over 39 mpg for simply slowing down.

 

Anyhow, like I said its not a practice for everyone, and I'm not going to say it is. But for me, going 600 miles on a tank that I used to average 480-500 on is worth it for me (I drive 120 miles to work a day, so it effectively allows me to only fill up once a week now.) I'm still in practice, but I've now set a goal of 40 for myself. If you can't handle it, then I'll be honest and say I'm not surprised. If you can, then you're not only helping your wallet but the environment as well. Here's my "proof" pictures, in case you want to consider it BS:

 

 

Believe it or not, I don't care. There's all the proof I have.

[draft]

You need to change your driving style if you want to dramatically improve your mileage. Don't get me wrong, I realize it is difficult for most people to really have under control. Here's my story:

 

I have always been fairly consistently at 32 mpg driving to work (mostly highway). But about 2 weeks ago, I read about hypermiling and I became extremely intrigued. I thought, what would it hurt to try it out for a little while? So, I gave it a shot. I began keeping my speed down (at the speed limit mostly) and doing a lot of coasting in neutral down hills and anywhere else I could manage. I started coasting to stop lights and stop signs and anytime the speed dropped I'd shift to neutral and coast down to where I needed to be. The first week I tried it, I managed just under 35 mpg on what was left on my tank. I was thinking, "that's pretty cool, but is it worth it to keep working on it?" I figured I'd try it out on a complete tank. This past Tuesday I got my results: 15.622 gallons and (gasp) 610.1 miles. That's just over 39 mpg for simply slowing down.

 

Anyhow, like I said its not a practice for everyone, and I'm not going to say it is. But for me, going 600 miles on a tank that I used to average 480-500 on is worth it for me (I drive 120 miles to work a day, so it effectively allows me to only fill up once a week now.) I'm still in practice, but I've now set a goal of 40 for myself. If you can't handle it, then I'll be honest and say I'm not surprised. If you can, then you're not only helping your wallet but the environment as well. Here's my "proof" pictures, in case you want to consider it BS:

 

 

Believe it or not, I don't care. There's all the proof I have.

 

I think thats a problem for alot of people

Doing just the speed limit is considered "slow" these days,

or at least thats how it is up here in Vancouver BC.. the norm is at least 30km/h over the posted limit

Say on the highway, limit is posted as 90km/h, 80% of ppl on the road drive 120km/h..

 

And you always get those douchebags that tailgate you until they either

A) go around you, and give you the stare down while passing you

B) Keep on your ass until you move to the other lane

 

And even if you move to the right, you're always going to get someone going more than the speed

limit, expecting you to move for them too!

 

But you always have ppl wondering how to save on gas

[cyclesucka]

Well, I drive 80 miles round trip per day, (All highway) and I try to keep the car on cruise control as much as possible. I hear that helps, but its not exactly doing the trick. I set the cruise slightly faster than the limit, but I am not speeding by people at 20 mph over the limit.

[CleanGSR]

Well, I drive 80 miles round trip per day, (All highway) and I try to keep the car on cruise control as much as possible. I hear that helps, but its not exactly doing the trick. I set the cruise slightly faster than the limit, but I am not speeding by people at 20 mph over the limit.

 

Same scenario as me. 80 miles per day all highway and use cruise at only a couple mph over the speed limit. I have managed to gain about 2 mpg on a full tank by shifting gears at around 2,000 rpms. THis is a lot tougher than it seems, but it helps and I"m getting used to the driving style change. I also coast down big hills when I can.

 

I'll try the coasting when the speed limit drops, and when coming up to a stop sign/light. I haven't been doing that, but that could maybe help even more.

[draft]

While we're on the topic of gas mileage, how much of a difference is there between a v6 and a 4 banger?

Is the 4 banger really THAT much better on gas?

 

Lets say an Acura 1.6 EL vs. an Accord V6 3.0L

I've always wondered this ever since I got my car

[Jeffro]

For the 6th gens, My 4-cyl is 26/32 EPA mpg and I think the V6 is something like 20/26 or something like that. You lose quite a bit. I know my truck gets 17/21 and its a v6. Its not even comparable, lol. There's a difference inthe AT and MT too, keep in mind.

[James Matteu]

While we're on the topic of gas mileage, how much of a difference is there between a v6 and a 4 banger?

Is the 4 banger really THAT much better on gas?

I depends on the technology. My 1986 12 valve CVCC SOHC inline-4 cyclinder Accord got the same MPG as my 1997 24 valve PGM-Fi SOHC V6 Accord: 19/25.

[mpearce1974]

Just recently I changed my driving habits as above, and went from 31 average to 34 average! Then last sat. took off power steering belt, I didn't expect much but thus far average went from 34 to 35.7 ish! I am running full tank through Sol this week and will see what happens. I am also considering a CX\VX tranny swap! Will post thread inquiring about one! Will be willing to trade D-series SI tranny for it!

[CleanGSR]

I just filled up after going through a tank driving 71-72 instead of 75 on the interstate. I also coasted as Jeffro suggested for the second half of the tank.

 

Fillup took 9.4 gallons

Miles driven on that tank was 320

equals: 34mpg

 

This is the best I've gotten yet and my previous best was a smidge under 32. My average when driving normal but easy is 30-31mpg. I'd say that's a good increase. I'm going to keep driving at 72ish (maybe just 70 flat when I'm not running late) and continue to coast. I'd love to hit a solid 35mpg.

[Turtlehead]

Well I drive between 1,000 and 1,500 miles a week, not including weekends...

 

Now that that is out of the way, has everyone forgot that they are driving PGM-FI cars (except for those driving very early modles)? Putting the car in neutral and coasting will only cost you more fuel consumption. I know first hand driving over 60K a year, plus working on them for a living. What happens is when you have the car in gear and you let off the pedal with PGM-FI is, the computer shuts off the fuel injectors almost completely. If you have a hill you are going down, keep it in gear and let off the accelerator, let the computer shut down the injectors, and let the engine brake/slow the car. You will not only save on fuel, but you will save on brakes.

 

My 95 Accord stock, manual, gets between 35 and 36 mpg. Driving style matters. Also, manuals get better fuel economy then auto's. A simple fact of life.

[James Matteu]

Also, manuals get better fuel economy then auto's. A simple fact of life.

:(

 

I know, but why did you have to say it.

[CleanGSR]

Well I drive between 1,000 and 1,500 miles a week, not including weekends...

 

Now that that is out of the way, has everyone forgot that they are driving PGM-FI cars (except for those driving very early modles)? Putting the car in neutral and coasting will only cost you more fuel consumption. I know first hand driving over 60K a year, plus working on them for a living. What happens is when you have the car in gear and you let off the pedal with PGM-FI is, the computer shuts off the fuel injectors almost completely. If you have a hill you are going down, keep it in gear and let off the accelerator, let the computer shut down the injectors, and let the engine brake/slow the car. You will not only save on fuel, but you will save on brakes.

 

My 95 Accord stock, manual, gets between 35 and 36 mpg. Driving style matters. Also, manuals get better fuel economy then auto's. A simple fact of life.

 

Say what you want but I've noticed a substantial increase in fuel mileage by coasting. Correct me if I'm wrong, but wouldn't the fuel injector's shut off (almost completely) when coasting and rpms at 1000 the throttle body is almost completely shut thus adding hardly any fuel (just like idle).

[Joe W]

Say what you want but I've noticed a substantial increase in fuel mileage by coasting. Correct me if I'm wrong, but wouldn't the fuel injector's shut off (almost completely) when coasting and rpms at 1000 the throttle body is almost completely shut thus adding hardly any fuel (just like idle).

 

My thoughts too, I mean coast anytime possible and get a close to 42mpg. Thats on 55mph highway with stoplights so combo of city/highway.

[Jeffro]

Well I drive between 1,000 and 1,500 miles a week, not including weekends...

 

Now that that is out of the way, has everyone forgot that they are driving PGM-FI cars (except for those driving very early modles)? Putting the car in neutral and coasting will only cost you more fuel consumption. I know first hand driving over 60K a year, plus working on them for a living. What happens is when you have the car in gear and you let off the pedal with PGM-FI is, the computer shuts off the fuel injectors almost completely. If you have a hill you are going down, keep it in gear and let off the accelerator, let the computer shut down the injectors, and let the engine brake/slow the car. You will not only save on fuel, but you will save on brakes.

 

My 95 Accord stock, manual, gets between 35 and 36 mpg. Driving style matters. Also, manuals get better fuel economy then auto's. A simple fact of life.

 

Letting off the gas still keeps the engine working at higher rpm's, thus, lower mpg. Shifting to neutral is dropping your rpm's to less than 1000. It's a very basic concept, and it does save on gas. And I'm not the only one clearly pointing this out. Personally, I don't care how many miles you drive in a year or how much you work on cars. If you can't see that 600 rpm's for a mile is better than 2000 rpm's for a mile, then I'm never going to trust you. Try coasting to intersections. Try slow accelerations. Try leaving your pedal at a given location when climbing hills, allowing your speed to slowly drop and continuing to hold that location on the pedal when dropping on the other side. These are all very basic concepts to save on gas, and all of them work. Like I said before, many people can't handle the driving slower idea, or the driving behind semi's or slow accelerations and I understand that. The link I included in my first post has hundreds maybe even thousands of individuals getting massive mpg by using these techniques. I'm spreading the knowledge, and it doesn't take me 60,000 miles per year to do it.

 

Edit: PGM-FI is simply stating that the ECU is calculating the appropriate fuel/oxygen level. Even with the engine idling, it is calculating the optimum amount of fuel and oxygen for that specific rpm. Unless I wanted to stop at the bottom of the hill I was coasting down, the best mpg is going to be in neutral (or better yet, turning the car off. But then you have to be aware of the loss of power steering and reduced brake usage after 2, maybe 3 good pumps.) Although you do bring up the point of reducing the use of your brakes to save on mpg. In my opinion though, saving on brakes is less important than wearing out a transmission or a clutch, so I'd hardly sacrifice using my brakes if I needed them.

[Jeffro]

I depends on the technology. My 1986 12 valve CVCC SOHC inline-4 cyclinder Accord got the same MPG as my 1997 24 valve PGM-Fi SOHC V6 Accord: 19/25.

 

I was referring to same model, different engines/transmissions. Of course there will be a difference among different vehicles... That's a given. You're comparing apples and oranges. I'm trying to compare apples and apples. Compare your V6 to the 4-cyl in the 5th gen and there will be a difference. I don't have a 2.2l though and the 6th gen can be an entirely different beast than those 5th gens...

[Turtlehead]

I'm spreading the knowledge, and it doesn't take me 60,000 miles per year to do it.

 

Edit: PGM-FI is simply stating that the ECU is calculating the appropriate fuel/oxygen level. Even with the engine idling, it is calculating the optimum amount of fuel and oxygen for that specific rpm. Unless I wanted to stop at the bottom of the hill I was coasting down, the best mpg is going to be in neutral

 

I guess there needs to be more explaination on the matter. A car equiped with PGM-FI technology functions on this basic principal: With the car in deceleration mode with rpm's 1,100 or greater and the throtle plate closed, the ECU cuts out the current to the fuel injectors through (on most cars the injector resistor), thus closing the injectors almost completely and shutting of the fuel supply. The motion of the car moving forward keeps the engine turning not fuel (for the most part). When the car is in neutral, the injectors have to open to allow for fuel to enter the system for detination, thus in neutral (idle) fuel is being used to keep the engine running. So, whether coasting down a hill with the car in gear or braking while the car is in gear (both deceleration modes) the injectors will shut down.

 

On the newer cars equiped with mpg indicators you will see the difference. This does not matter whether it is a Honda or a 98 Town and Country minivan. To compare a newer car to an older one is not entirely complete, as each cars technology may shut off the injectors a different amount; however, the basic principal of cars equiped with PGI-FI technology (most car built after 1990) will shut off the injectors (almost completely, near 99%) when the car is in deceleration mode with rpm's above a certain threshold (90's series accords 1,100 rpm), and the throtle plate closed.

 

To answer James question on manuals vs. auto's and fuel economy, the basic principial is you have greater control of your driving style. Auto's will shift down every time the car sense the need for more torque. Most fuel consumption occurs during heavy acceleration, and and auto's you have a decrease in control of the time of shifting. Ok, actually not, but what I have found and seen is that people are a lot more conscious of rpm's etc. when driving manuals vs. just driving down the road with and auto. Sorry I can not explain this any better, but everyone I know that comes in with cars, when you are talking fuel economy, the manuals are always better then the auto's when comparing same make and modles. I guess it has to be better control over your driving style. It could also be perhaps a difference in the 5 gear gear ratios between the two. Not sure on that. I will check into that for my own curiosity.

[CleanGSR]

Please post the resource that you got your info from so I can believe you. If you are quoting info someone else told you then that doesn't make it true, but I'm assuming that you have actual technical info somewhere to back this up.

 

You honestly believe that if I sit in my driveway and let the car idle for 1 minute that I will use more gas than you coasting down a hill with the car in gear at 2000-3000rpms? I'm sorry, I just don't believe it unless you can post some credible technical source for your info.

[mpearce1974]

+1

 

I agree! I have been doing a lot of experimenting lately! Still waiting to see how big of a diff. removing ps belt makes, but looks promising so far!

[Jeffro]

Please post the resource that you got your info from so I can believe you. If you are quoting info someone else told you then that doesn't make it true, but I'm assuming that you have actual technical info somewhere to back this up.

 

You honestly believe that if I sit in my driveway and let the car idle for 1 minute that I will use more gas than you coasting down a hill with the car in gear at 2000-3000rpms? I'm sorry, I just don't believe it unless you can post some credible technical source for your info.

 

Don't forget that ANYTHING that slows you down will ruin your gas mileage. If you're using your transmission to slow you down, then you are losing your forward momentum, you are not going to coast as far at speed, and all that fuel you used to build speed will be wasted since you slowed down. Same as using brakes.

 

I can understand if you want to say its better for an automatic, because going in and out of neutral and drive is going to be hard on the transmission, and you have to worry more about rev-matching etc. to protect your transmission, but that is about the only argument I can see. I've proven improved mileage using it. Prove better than 39.05 mpg using coasting in gear.

[Xeryon]

Don't forget that ANYTHING that slows you down will ruin your gas mileage. If you're using your transmission to slow you down, then you are losing your forward momentum, you are not going to coast as far at speed, and all that fuel you used to build speed will be wasted since you slowed down. Same as using brakes.

 

This was what I was thinking. With the car in gear and you coast you have the parasitic drag of the engine acting on the wheels. In this instance, as you noted above, the engine is actually rotating because of the motion of the vehicle. With the car out of gear the engine will be expending a miniscule amount of fuel to stay running, but you will be freewheeling and a freewheel coast from 55 can take most cars at least 1/2 mile or more.

 

Don't know if this was mentioned above or not (can't remember), but make sure you never downshift as a method to slow down. When the car revs up due to the lower gear you will be using more fuel then too. Most people know this, but it's not something a lot of people pay attention to when driving.

 

Something I recall reading about, and this goes along with Hung's comment about a hot-air intake were people putting a restrictor on their intake. Via the same method that larger cold air intakes are supposed to improve power having a smaller intake should improve mileage. I was thinking of cutting a section of pvc that was just a bit smaller then the diameter of my intake and sliding it into it to make the inside diameter a bit smaller. I should loose a little power, but should gain 1-2 mpg i think.

 

And Hung made a comment earlier which I disagree with, but it would take someone more knowledgable then I to prove it. A larger tire, mathmatically, should cause you to get a worse milage. The larger tire puts more weight further out from your axle, which makes the engine work harder to rotate that wheel. This goes along with the line of thinking with the VX 13's wheels. They were made of a magnesium alloy and were smaller so the majority of the rotating mass was closer to the hub which was easier for the engine to rotate and saved fuel.