I recently purchased an '02 Civic Si. I assumed since it was rated about the same for fuel economy as my '95 integra SE it would get about the same gas mileage. However I always got 32-34 mpg in my integra, and since I've owned my ep3 I've only been getting 25-27. I use/used premium gas (yes I know its debateable) in both, and both are about 50/50 freeway and city driving. Is this normal, or should I be getting better?

 

Si has higher gearing... if you notice when you are at 60 mph you are around 3k RPM compared to 2.5k in the teg... so it is a little normal.

I average 27 city/fwy and 31-33 fwy only...

 

Have you done a tune up to make sure everythings good? Oil and filter change. Cleaned or replace intake filter. Injector/fuel cleaner. Tire pressure check.

 

I figured he had done that but good point

 

I've done a basic tune up, switched out the fairly worn Bosch plugs for new ngk iridiums, used Lucas fuel cleaner twice, used Honda top engine cleaner, and I'm hoping to get the trans fluid changed tomorrow. Unfortunately it does have a short ram intake and magnaflow muffler, I did clean and reoil the filter though. Tires are all about brand new, and at correct pressure. Oil appears to be synthetic and freshly changed, but it is on my to do list.

 

yeah i always feel like i should be able to shift into 6th to get the rpm's down in my ep

 

i get about 28 city and 32 hwy, mine has been tuned up etc. i normally am not the slowest driver though..

 

I like this guy.

My fuel economy is about the same as yours. Check out a website called Fuelly.com, you can track your gas mileage and also compare your car to other registered EP3 owners to see how you stack up to their MPG numbers.

Here's my page info.. haven't updated it for a while though lol.

http://www.fuelly.com/driver/sleep3r/civic-si

 

Same here..., wait, I do have 6th gear!!! LOL..., I sound like an ***.

With all the mods, I get about 22/27, city/highway respectively. And I do drive more on the spirited side.

 

I just changed my trans fluid, and discovered it was unfortunately filled with engine oil, that wasn't real clear either. So hopefully Honda mtf will improve mileage some.

 

it won't improve... engine oil isn't a bad lubricant! It can do the job... The oil is there to make sure that during your gear changes everything is smooth and to cool the inner case of the tranny. In no way will it make any difference with your gas mileage!

 

you can still find that honda top engine cleaner?

 

Ya, my local Honda dealer stocks it. I get it for $3, but that's after a slight discount.

 

I bought gas today, and was getting a little over 29 mpg, this tank was partially before and mostly after changing my trans fluid, and was about 60/40 to 70/30 city/hwy. So the fuel economy has gotten somewhat better.

 

yeah, my Si mpg sucks too. during the summer, i got 28mpg highway. ive been told there is an additive to "winter" gas that helps with initial start up, but hurts gas mailage. when i tested my mpg a few weeks ago... 26mpg highway. ill admit, i drive about 80mph on the highway most of the time. i know thats part of my problem, but driving 65-70 i feel like im barely moving.

my car is also supercharged, so i guess these numbers arent horrible, but not what i was expecting or use to. my previous car was a b16 del sol, and it got somewhere around 35mpg on the highway.

ive been thinking 6 speed swap is in my future, but idk. maybe a new car...

 

Your 5th gear on the B16 was longer and not shorter like the K20... going 6 speed would probably help a little!

 

who wants to be the guinea pig?

http://www.youtube.com/watch?v=UHAUsGlfbx8

http://www.youtube.com/watch?v=9514DMTTTuc

ive done a little research, and there are mulitiple cases of this working. increasing mileage 8-35%!!!

 

why are you using premium? I was under the impression that the k20a3 ecu was calibrated to use 89 octane?

 

where did you hear that?
i pump premium into my k20a3... o.O

 

The ECU "learns" to adjust for the higher octane. It changes the tune for moar pow3r.

 

Combo city/highway I average about 28 to 30.

 

again where did you hear that o.o

 

The timing of the EP3 is setup for regular 87 octane.... but if you use 91 octane the ECU after a couple of thanks will readjust the timing.

Basically you can use 91 octane but its a waste since the cars timing was for regular 87 octane. Although if you have KPRO or the reflash done it is a must you use 91 octane as the timing is advance!

This is something that was noticed a long time ago from people testing it out!

 

I have kpro

 

i just bought an ep3 about 6 weeks ago and i changed:
spark plugs to ngk iridiums, oil to 5w20 synthetic, trans fluid w/ honda mtf, tires are 215/60/r15 at 36 psi all around, added 1 bottle of gumout fuel system cleaner and 2 bottles of heet (at different fill-ups) and i have no cat (bought it like that)
i drive about 50% hwy & 50% city and i've only been getting 20-24 mpg
what else can i do?
the car's dropped 2" (maybe more) and weather's been 0-20°F for the past month
could that be a factor?