Hello,

I'm new here. I just purchased a 2003 EP3...I've been driving it for just over a week. I was told I should be able to get high 20 to low 30 mpg on a full tank. At the moment, I think it's draining more than my brother's Type S RSX (with a heavily modified/tuned engine).

So far, I changed the oil, put a new filter on...checked the sparkplugs...I'm new to the car, and I'm not sure what else could be causing the problem. Is there anything else I should do?

I also noticed I may have this inconsistent gauge problem that some seem to have with the car.

Thanks very much...

 

o2 sensor? I had poor mileage on my civic (not EP3) and it turned out to be an o2 sensor

 

Hey, thanks for the suggestion, church. I'll definately give that a try.

 

I don't think you ever stated what your actual mileage was? I had one for 5 years and I averaged about 26-27 mpg. You can't judge mileage based on one tank. You need to do it every tank to get a good idea of what your mileage actually is. Your mileage *will* change from tank to tank significantly. Also, you just got the car and I am assuming you're enjoying it so maybe your foot is a little heavy?

 

if o2 sensor was the problem it should be throwing a dtc for it, dont just change it cause you think thats the problem,thats what the pcm is for and obd2 is smart enough to catch that. any trouble codes?? if not im with this guy ^^^^ your foot might be heavy and you might now even notice it, car is rather slugish trust me i know .lol

 

Thanks guys...I work a little bit away from home, and I've been doing a fair amount of city driving, so I'm no longer on my first tank. As for being foot heavy, I usually shift around the 3k range (plus / minus).

I was inspecting the inside of the exhaust yesterday, and there is a little bit of black buildup, which would indicate that the car is running slightly rich (I didn't notice this when I bought the car). The tank still had a little bit of gas in it yesterday, but I filled it up full. Basically, with a little bit of city driving, mainly highway driving, and a little bit of idling in traffic, I'd estimate about 430-440 km out of the tank.

During all this time, I didn't hit vtec more than 4-5 times, max. I was trying to keep the car in the lower rpm range in order to judge the gas usage.

Anyway, thanks for the help guys. Maybe I'll just take the car for a tune up with a mechanic that I know.

 

This is not necessarily the case. Have you ever heard of a "lazy" O2 sensor. I have seen many in my shop. Now I am not suggesting just run out and change the 02 sensor either. I would expect new car excitement to be the issue. As stated above fuel mileage can not be based on one tank of fuel either. When fuel was over 4$ a gallon almost every customer had fuel consumtion concerns. This is how to calculate fuel mileage. Go to filling station, fill with premium fuel only until the pump shuts off by itself. Drive car normally for 25 miles. REturn to same filling station,same pump, top off until pump shuts off. Record how much fuel you installed. Do math from there. Good luck. Also note that octane boosters make you use more fuel, also loads on the engine make you use more fuel like A.c.

 

The residue on the inside of the tailpipe doesn't necessarily indicate that the mixture is rich it could be lean and still leave carbon deposits so I wouldn't rely on that. Keep tracking your fuel mileage over months, not weeks, and do the math using your odometer, not your fuel level gauge.

 

If you could, please tell people what you're actually getting for mileage. Estimating mileage out of a tank is imprecise and isn't giving people the right idea.

There isn't a lot to "tune up" on an EP3 K20, so be careful what people tell you they are doing. If the mileage is high enough, there might be a few things to replace, but not much. It's basically an extremely reliable and understressed motor as long as people leave it alone.

As someone else said, the dark tail pipe residue should also not be used as conclusive evidence of anything.

I really think that the first thing you should do is tell us your real mileage.

I used a USDM EP3 Si as a daily driver/commuter car for about 2 1/2 years, and I seemed to get 30 miles per gallon no matter where I went.

 

If you shift at around 3k all the time you have hitting VTEC all the time as it kicks in at 2200 RPM FYI...

Also did you change your air box filter?

 

Below 2000 RPM one of the intake valves stays closed, which is part of iVtec but the camshaft profile switching part still occurs at higher RPM.

 

Check your tire pressure

 

Thanks for all the help guys. I will keep all of this in mind.

DaveSi677 > I have a new Fujita intake, and a new filter.

turboteg2nv > Yup, it's all good, but thanks

I'm not going to bother with all of the US conversion right now, but I can make 450 km (280 miles) on a tank...pretty much everytime...which seems to be less than most people that I've spoken to. As for the ivetc, I realize that it's different from say an RSX TypeS, but shifting below 2200RPM every time is kinda low...

Anyway, the point is, there is no way the car should drain more/faster than a heavily modded 2003 Type-S RSX. Everything else seems to be perfect, and I'm very happy with the car. I just wanted some advice from EP3 pros/experts such as yourselves.

Mega thanks!!

 

There's a fairly "standard" list of things to check when gas mileage is a concern. On an EP3, I'd make the list as...

Spark plugs
Fuel injectors
Tire pressure
Alignment
Parking brake adjustment / check brakes not dragging

And, that's pretty much it. Gas mileage is extremely dependent on driver, terrain, temperature, speed, etc. You can't just say your car should do better than xxy car, and expect that to be true in any given situation.

A modded RSX may have a very lean gas mileage tune, less rolling resistance, more aerodynamic, and drive slower than you everywhere he goes with a taller final ratio.

 

Hey, thanks shifty35! I've checked everything out already, but I'll double check, etc...the previous owener did mention that his brakes locked up on him. However, they were already checked out, and seem to be ok.

Anyway, like most of the guys have suggested, I'm probably just going to keep an eye out overtime.

 

fuelly.com will help you track your mileage and compare it to other EP3 owners.

 

if you are making 280 miles per tank be happy. I only average about 250 miles per tank.

 

i just took my civic on a 300+ mile journey to get fireworks, on the way down id bet i averaged 90mph or better, on the way back cruise control set at 78 almost all the time or untill i could see far ahead.. my car got about 31 mpg, i thought that was good for for making good time all the way down.. oh yeah, i havent burned hardly any oil with the 30 weight in it either... im obout 2k into the oil change.. a lilttle off topic but thought id share

 

I just reached 170,000 miles on my ep3, I average about 33 mpg on the highway and roughly 26-27 in the city, although I burn a quart every 2,000. Pretty happy with it, ep3 is one hell of a DD. Getting ready to pick up a block to rebuild and swap in, while I am at it I am going to do the accord 5th gear swap, lower the teins a little bit, get some new 195-60 tires, hoping for 37ish mpg when all said and done, its going to be the fuel efficient build lol

 

It seems all of you are being imprecise with your mpg estimates.

Reset the odometer when you go to the gas station
Fill all the way up
Drive around until you're getting low again
Note the mileage
Fill all the way up

Divide the mileage recorded by the gallons put in. Tada! Saying you get XXX per tank is VERY inaccurate.

 

this is exactly how i do it everytime.. i used under 10 gal to go 300+ miles.. forget the actual numbers but it came to about 31mpg on my journey!

 

Heavy foot most likely, BUT, like the guy above of me said, USE PREMIUM GAS! I used to just fill up with unleaded but I was getting 22-25mpg freeway! I use premium only now and get 30-34mpg easily, Unless of course im flooring it.