EP3 - maximizing your MPG

[bartine]

I have a 2005 Civic Si. I love the car.

I take several trips a month for work. On these trips I have averaged 28mpg. If I could increase my MPG to around 40mpg, I would save $800 over the next 30k miles

My question to the board - who has modified their EP3 to maximize MPG?

Has anyone done some mods that increased their engine's efficiency?

K-Pro Mods - I've heard some brief discussions on tuning the engine using K-Pro to almost reach lean burn status, but have never heard the fine details. Has anyone used K-Pro to increase MPG? What are the settings you used? Results?

How about putting in a 6th gear. What was your miles per gallon before and after?

Tires? The effects of different mods?

[jed_averill]

I'm looking forward to this. One basic way you can increase your MPG is change your driving style (no fast acceleration etc etc).

[emsep]

my engine is stock except for an k&n drop in filter. on my last fill up i averaged 34mpg. i dont drive fast. i shif under 3k usually at 2.5k and drive under 70 when on the freeway. i think 34mpg is good considering i have over 188k miles on my engine. hope this help.

[jed_averill]

Check other forums. I saw one forum that has EP3s that have 40mpg or close to it. I don't remember the site because I saw it through google.

[27rocks]

Great ways to increase milage:

Take out anything you dont need in the car. The lighter the car the better.
Make sure all your fluids have been serviced. Oil being #1 in this case.
Proper tire inflation.
Cruise control is your best friend!!
And drive it like a grandma when going from light to light or sitting in traffic.
Some people go as far as turning their cars off when having to wait for longer than a minute (this actually helps quite a bit).

Just remember that the motor wastes the most gas and works its hardest at idle.

[Mighty_Mouse_Ep]

Also check your tire pressure. Under inflated tires burn more gas.

[ttttrigg3r]

I turn my car off when I don't make a light. it dropped me from 30mpg to 28. I'm still doing it though.

[bartine]

I found an EP3 discussion on Ecomodder which discussed driving tips to maximize fuel economy:

http://ecomodder.com/forum/showthread.php/ep3-k20a3-drivers-give-me-tips-please-3673.html


One of the members has a ScanGuage on his Civic Si and ran some tests - the findings are below. He had not done any mods.

Shifting: 2800-3000 rpm yields the best gas mileage (right after VTEC kicks in)

All tests were run at 5th gear, no ac but sunroof open (has a sunroof visor so drag isn't as bad)

at 40mph on 5th with LOD 43 SG showed 37-38 mpg
at 45mph on 5th with LOD 38-40 SG showed 38-39mpg

At 50mph with LOD at 38-44 SG shows 37-39 MPG
At 55mph with LOD at 40-45 SG shows 35-36 MPG

At 70mph with LOD (can't remember) shows 29-30mpg
At 80mph with LOD (can't remember) shows 28-29mpg

Total 64miles driven with an avg of 34.2mpg. I forgot to check what it shows at 40-45mph on 5th. I would guess it would be around 38-40mpg. My tires are at 31 psi (cold).

[bartine]

This thread on Ecomodder is the the one that really spiked my interest. It discusses tuning the car for a lean burn air to fuel ratio.

*** Vince - are you out there? ***

http://ecomodder.com/forum/showthread.php/k20a3-tuning-economy-3401.html

The major points are below, but again - no final results.
Has anyone used K-Pro to tune for a high air to fuel ratio (opposite of tuning for power)? While the gearing isn't optimal for fuel economy, the K20A3 engine is actually much more advanced than the VX engines.

----------------------------------------------------------------------------------------------------------------------
One thing that this engine doesn't come with is lean burn though. Maybe it was to reduce Nox emissions or something like that but the most important thing is that this engine is @ least as capable to operate in a tuned leanburn mode as the d15z1 and d16y5 engine

So one of my coworkers went on a road trip in his roomates EP3 and since it already had Hondata KPRO installed he started messing with tuning it for a mild leanburn cruise. From what he said its running 18:1 @ light loads under cruise and on the freeway doing 80+ mph it was getting around 40 mpg

The engine was leaned out to 17-18:1 without any noticeable changes in how it ran, misfiring, ect. The speeds were very ecomodder unfriendly @ 80-90 mph but the newly tuned engine burped out 41 mpg The total trip mileage was approx 850 miles.

With a more capable wideband controller and NTK sensor he should in theory be able to run up to 25:1 ratios and my local professional tuner confirmed this also. He also could raise the stock vtec engagement point from 2200 to about 2700 for in city gas sipping.

[ep3egg]

dont accelerate quickly
use cruise control... if on the freeway of course
turn off your AC

[Deadphishy]

Raising the stock Vtec point any higher will more then likely burn more fuel. The motor will have to work to hard to air in, and you will have a TQ dip for sure.

I have tuned my car to run lean a few times with good results. However i do not have an EGT guage, 18:1 seems like the motor might get a bit to warm. If the burn is to lean, you could melt the pistons and or warp the head. Highest i ever did was 16:1 that got me about 35-36MPG highway. On my 2.4L I will be doing the same thing to my k20a2.5 now. I have stage 2 cams in, so if my MPGs arn't around 40, i'll drop in the stock cams.

[Passenger]

Get in touch with Scotty @ DigitalBoxTuning///Mainstream Performance in Dallas, GA and see what he'd say about tuning it for fuel efficiency using KPro.
The only thing I can contribute is take it easy on the air conditioning. When I use the a/c cause GA heat and humidity combo sucks, it kills my MPG drastically and I use cruiseconrol quite a bit during school days.

[chiwhitesi]

If you are looking to Mod the car for more efficiency i would suggest you remove as much weight as you can be comfortable with, narrower tires, full tune up, and make a complete under tray

[Hasbro]

Right now I'm working out of my EP but used to average around 38 mpg. I was getting 42 but that was with high tire pressures, 60-70. For 38 mpg I used pulse and glide - not cruise control, -300 lbs, high tire pressure - about 50, stock tires, no ac, 2200-2700 rpm shifts, etc. Nothing extreme and I would still rip around corners. A heavy pedal is a real killer. K Pro and a higher final drive or sixth gear would really help. I still get a steady 32 mpg making very short drives and stops so it doesn't warm up. That's a major mpg killer but 32 is very good considering. I do plan on going with K-Pro, sixth gear and higher final, taking off 200 more pounds and doing some aero mods and using car just dd, not work. I don't see why I cant average mid 40s, even with wide tires. The EP could do 50 mpg if done right.

[Passenger]

That's probably the highest out of an ep I've heard of

[codyep3]

sell ep3, buy crx

I was planning on buying a crx as a Daily and make it into and engineering project. To create the most aero, fuel economic car for only 3gs lol.

[Stanz0r]

Just remember, you might increase your gas mileage 10mpg but if it takes you 100,000 miles to recoup the cost is it really worth it? Something to think about before people run out to buy K-Pro, a sixth gear, etc. Figure that factor out before doing anything.

Best advice is to do the free stuff and keep up with your maintenance.


Shift early, without lugging the engine.
Keep a light foot on the throttle.
Keep your tires properly maintained. Increase pressure if you can. Consider switching to low rolling resistance tires when you're due for new tires.
Keep your oil changed regularly.
Don't coast in neutral! You burn gas idling this way as opposed to leaving it in gear while coasting which burns no gas.
Use cruise control when applicable.
Don't tailgate. You might help increase gas mileage somewhat, but it's pointless if you keep having to slame on brakes then speed back up.


Read up on hypermiling (sp?). You can find a lot of good info from that as well.

[jed_averill]

Don't coast in neutral! You burn gas idling this way as opposed to leaving it in gear while coasting which burns no gas.

WHAAAT lol I learned something more important than my classes today.

[Hasbro]

Just remember, you might increase your gas mileage 10mpg but if it takes you 100,000 miles to recoup the cost is it really worth it? Something to think about before people run out to buy K-Pro, a sixth gear, etc. Figure that factor out before doing anything.


It's not economically viable for most but neither is building an EP into a 300 hp corner carver. But we do it. I plan on keeping this car for many years and it's a good modern dependable platform for my purpose. A 40+ mpg dd that weighs 2275 lbs., handles well, and hauls 3 mtn bikes.

[codyep3]

lol i call you on 40+ mpg in an ep sir.

[powdbyrice]

Add Garcia choppys. Profit.

[ttttrigg3r]

what would you consider lugging the engine? Can anyone describe in the clearest term lugging the engine?

[ttttrigg3r]

Just remember, you might increase your gas mileage 10mpg but if it takes you 100,000 miles to recoup the cost is it really worth it? Something to think about before people run out to buy K-Pro, a sixth gear, etc. Figure that factor out before doing anything.

Best advice is to do the free stuff and keep up with your maintenance.


Shift early, without lugging the engine.
Keep a light foot on the throttle.
Keep your tires properly maintained. Increase pressure if you can. Consider switching to low rolling resistance tires when you're due for new tires.
Keep your oil changed regularly.
Don't coast in neutral! You burn gas idling this way as opposed to leaving it in gear while coasting which burns no gas.
Use cruise control when applicable.
Don't tailgate. You might help increase gas mileage somewhat, but it's pointless if you keep having to slame on brakes then speed back up.


Read up on hypermiling (sp?). You can find a lot of good info from that as well.

About the coasting. ARE you sure? I thought you're supposed to put in neutral to get lower RPMs when coming to a stop.

[jed_averill]

About the coasting. ARE you sure? I thought you're supposed to put in neutral to get lower RPMs when coming to a stop.

It makes sense. Staying on gear does not require the engine to burn gas (your car moving alone keeps the engine alive), but going on neutral requires the engine to burn gas to keep idle or else it stalls.

[Stanz0r]

It's not economically viable for most but neither is building an EP into a 300 hp corner carver. But we do it. I plan on keeping this car for many years and it's a good modern dependable platform for my purpose. A 40+ mpg dd that weighs 2275 lbs., handles well, and hauls 3 mtn bikes.

That is true, to each their own. What I was implying however is that some people only see the increase in mpg. I was stating that it is pointless if you save $x in gas but spend in $x*2 in mods to obtain the better gas mileage. Hence why I recommend going with the free stuff and proceeding from there.


what would you consider lugging the engine? Can anyone describe in the clearest term lugging the engine?

http://www.cartalk.com/content/columns/Archive/2005/August/07.html
That somewhat gives an explanation. For me it's more of how the car feels, it feels as if the engine is struggling to accelerate. Basically the way it feels if you tried taking off from a stop in second or third gear.


It makes sense. Staying on gear does not require the engine to burn gas (your car moving alone keeps the engine alive), but going on neutral requires the engine to burn gas to keep idle or else it stalls.

Exactly that. For furthur proof you can confirm it in K-Pro by checking the injector duty cycle. Always showed 0 when in gear and no throttle vs a small number when in neutral. Probably insignificant, but it does burn gas regardless.

[josetequila]

well do what i did, found a good job plus they pay my gas, i carry a company credit card, an i was told my the boss its ok for me to pump gas ones a week...... that saves me tons of cash...lol

[bartine]

I get reimbursed for mileage on my long trips, which is nice. I feel the financials do support trying to bump up the gas mileage, to a point.

I have 71k miles on the car now, and plan to drive it another 100k. I now get 28mpg average on my trips. It actually doesn't take too long to reimburse costs to a point.

With gas at $2.50 per gallon:

30,000 miles at 28mpg = $2,680
30,000 miles at 40mpg = $1,875

Cost savings of $800

If I drove 60k miles, save $1,600

Plus, if on rare occasions I happen to tune the car for performance instead of efficiency, well then that is just a nice to have benefit, but not at all why those mods were paid for.

By the way - back in the day my wife and I owned a CRX HF - it got crazy gas mileage, handled well, but with the airplane gears in that 5 speed it was a dog to drive. And - when some idiot rear ended her at a stop light, you could take your elbow and put it on the back bumper while sitting in the drivers seat. Newer cars are heavier, but perhaps a bit safer.

[oh5ivehatch]

Hello, every1....This is a topic that I keep going over with my father........but let me ask every1 else something?
Is my gas mileage going to be off if you run non-standard wheels and tires.......
I also have a K&N Typhoon short ram intake, Magnaflow cat back exhaust, and 18x7 wheels with 245/40/18 tires........
I just bought this car used 127000 miles on it when i got it.....it already had the add-ons already.

thanks in advance every1,

oh5ivehatch

[27rocks]

Hello, every1....This is a topic that I keep going over with my father........but let me ask every1 else something?
Is my gas mileage going to be off if you run non-standard wheels and tires.......
I also have a K&N Typhoon short ram intake, Magnaflow cat back exhaust, and 18x7 wheels with 245/40/18 tires........
I just bought this car used 127000 miles on it when i got it.....it already had the add-ons already.

thanks in advance every1,

oh5ivehatch

If the radius of the wheel tire combo is larger yes. Also if the wheel is heavier than stock.

[02 honda civicS]

I drive locally in the city all the time so my mileage is probably the worse out of everyone. Stop and go in traffic majority of the time the car is running. Im hoping to get around 20mpg, which is actually pretty good compare to my other cars.

[bartine]

I had thought about a Hondata Re-Flash, but found out that my 2005 Civic Si isn't compatible. Bummer.

Other than K-Pro at about $950, is there another more affordable ECU controller I should look into that would let me control air to fuel ratios?

[27rocks]

I had thought about a Hondata Re-Flash, but found out that my 2005 Civic Si isn't compatible. Bummer.

Other than K-Pro at about $950, is there another more affordable ECU controller I should look into that would let me control air to fuel ratios?

You have the same engine as any other Ep so i don't see why it wouldn't work.

[EpThreeD]

yea, theres options but are the cost effective? To put in a 6th gear would cost you more than you would save over the next few years. its better than a lot of cars but most of those are sedans and bigger cars. if the crz wasent a 2 seater i would have already traded.

[27rocks]

yea, theres options but are the cost effective? To put in a 6th gear would cost you more than you would save over the next few years. its better than a lot of cars but most of those are sedans and bigger cars. if the crz wasent a 2 seater i would have already traded.

The CRz is not as good as everyone thinks it is. And even if it had back seats what would you really be able to fit back there??

[ttttrigg3r]

Ok my question will end all my confusion. I just want to get this clear. If I'm in gear and I just let off the gas pedal, that mean there's no more gas getting injected and the car's momentum keeps the engine running. Is that right?

[Stanz0r]

Ok my question will end all my confusion. I just want to get this clear. If I'm in gear and I just let off the gas pedal, that mean there's no more gas getting injected and the car's momentum keeps the engine running. Is that right?

Yes.

http://www.popularmechanics.com/cars/how-to/repair/coasting-in-neutral-fuel-economy

http://editorial.autos.msn.com/blogs/autosblogpost.aspx?post=1787778

etc.

[EPSU3]

Good luck. I got 42 mpgs on two tanks a few years ago. I thought it was a mistake but it was purely highway, my tires were inflated and nearly bald. (I don't recommend that obviously) I have no idea if this would be a variable but I also had HFP side skirts. Once I took them off and got new tires I was back at 34 mpgs. To college and back is exactly 402 miles so I made that trip often but was never able to reproduce the 42 mpg that I did on those crappy tires.

[J Mo]

Good luck. I got 42 mpgs on two tanks a few years ago. I thought it was a mistake but it was purely highway, my tires were inflated and nearly bald. (I don't recommend that obviously) I have no idea if this would be a variable but I also had HFP side skirts. Once I took them off and got new tires I was back at 34 mpgs. To college and back is exactly 402 miles so I made that trip often but was never able to reproduce the 42 mpg that I did on those crappy tires.

interesting, seems like your balding tires had the effect of low rolling resistance tires, because less grip = less friction = less force needed to keep on propelling car forward

[ttttrigg3r]

Yes.

http://www.popularmechanics.com/cars/how-to/repair/coasting-in-neutral-fuel-economy

http://editorial.autos.msn.com/blogs/autosblogpost.aspx?post=1787778

etc.

My driving habit is going to totally change. Hey 42mpg? I think I got 38 once on a trip from socal to lake tahoe, NV. Happiest I've ever been with my car.

So low resistance tires would help improve mgp on a dd? Guess I have to read into that.