New from Oregon
 

Hello all, I recently bought a 2004 Civic HX. My last car was wrecked (2008 Sentra) and I never concerned myself with its mpg (29 average). But when I started looking into a new vehicle I decided that i should start paying attention, especially since we might be buying a house soon, and my daily commute will likely become longer. I settled on a civic of some kind and I preferred to find one with a 5 speed, AC, and cruise. I picked up the HX with 137k miles for pretty cheap, it has a rebuilt title but is in good shape otherwise. The car needed a primary O2 sensor right away, and needs some other preventive maintenance (I'm going to be changing the timing belt this next weekend), plus some tires. All in all I think I got a great deal, and its way more fun to drive than my old Sentra. Shortly after I bought the car I had filled the tank. yesterday my new sensor came in and I installed it. I then went to fill it again to see what my mpg had been with the other sensor disconnected. The trip was 214 miles and it took 5.8 gallons so about 37 mpg. My daily commute is about 35 miles round trip, pretty much flat, and 2/3rd highway at 65. Since I've started paying attention to economy, I started driving the speed limit everywhere instead of the usual 5 to 10 over like I used to. Now I will generally set the cruise right at the speed limit, and just drive in the far right lane. Most of the time I might have to occasionally pass a semi (3 lanes each way), but most of the time that lane is clear for long stretches.

Some observations: I've noticed that the people that speed past me tend to be waiting at the off ramp light when I get up to it. I never noticed that before and it makes me wonder how much money I have wasted all these years. I also like the peace of mind knowing that I don't have to watch out for the cops because I was speeding. I have also seen my speedometer seems to be a couple of mph off. I have not yet had a chance to check the odometer against the mile posts, but according to my GPS, I'm about 2 mph slower than what the gauge says. It could be the worn out tires, but its still about 2 mph at several speeds including 30, 40, and 65. I am thinking that if the odometer checks out ok, someone must have taken the needle off at some point and put it back on slightly off. If the odometer is off too, then my logic says its in the tires. They are stock size.

Maybe I can convince the wife to let me get a ultragauge for christmas or something, that might be nice to have. In the mean time, I might try and rig up a LED or use a vacuum gauge to tell when the car goes into lean burn mode. So far I cannot tell by feel. It could also be that the car had not been using the lean burn mode with no primary O2 sensor connected.

Welcome to the site! Congrats on one of the last HXs ever made. It'll be interesting to see what kind of mileage you can eek out of it.

You'd be correct in assuming that without the O2 sensor, you won't go into lean burn mode. Now with the new sensor you should be able to tell the difference.

Are you considering any modifications? Some aeromods would definitely do you good at 65 mph.

yeah, its seems almost all the references to the HX model are from 6th gen civics, not too many 7th gen ones.

as for the the aeromods, probably not. I dont have a whole lot of time or money to devote to this car. maybe some small things like a radiator block, or some kind of lip. an undercar something would be nice from the noise perspective.

with lean burn, what should i be expecting to feel? where would i feel it, in something like pedal resistance?

The lean burn threshold in my 2000 Insight was noticeable because the pedal response got noticeably duller even with small adjustments. Also, the car made an almost imperceptible stumble when it transitioned between lean burn & regular. But I think other Insights didn't stumble.

Gauge: you'll want an MPGuino, because it'll properly show your fuel consumption vs. a ScanGauge or Ultragauge (which will not properly report lean burn consumption -- they always assume a 14.7:1 ratio). Do some seaqrching here for more info.

Oh, and also: congrats on the HX, and welcome to the forum!

Thanks. I think a MPGuino and maybe a vacuum gauge or something might be in my future.

You can peruse the thread in my signature for ideas. I have an '01 HX.

When lean burn engages it feels like the engine stumbles just a little and makes a little less power. When it disengages, there is a slight surge. It's very subtle, and likely you won't notice it until you get a gauge to verify when it happens.

The MPGuino will be most accurate, but I like the Ultragauge for the wide range of useful features at a very reasonable cost and easy install. I'm just aware of the fact that it is inaccurate under lean burn and don't put much faith in it if I use lean burn a lot. When I do use lean burn a lot, my mileage for the tank is higher than what is reported on the Ultragauge.

so what you are saying is, the ultra gauge is very useful, but use another method at fillup to determine average mpg?

Regardless of what gauge you use, the most accurate way to determine MPG is to fill up your tank and divide your miles driven since the last fill up by the total number of gallons pumped. Partial fills will be less accurate than only filling up when the tank is near empty.

I still use the MPG readouts on the UG to gauge how good I am doing for a particular tank or stretch of driving. But it will be off by a small percentage.

I also use Pulse & Glide a lot, and in my car I can't easily get it into lean burn when I do. The more you use lean burn, the farther off it will be.

yeah, at this point i am not interested in P&G, i generally set the cruise and just steer straight ahead.

Look at the technique called Driving With Load. Use that with cruise control and you can improve your economy over just letting the cruise control do it's thing. As you go up a hill, bump down the CC speed, as you go down a hill have your CC accelerate.


This is by design.

Regulations vary by country, but Europe and Australia require speedos to be accurate to +10% plus 4km/h but never below actual speed. US has a similar, but more complex standard that covers the allowed range. To comply with the regulations, they typically indicate 1%-2% high.