Consistent over 41MPG highway with Civic

[chilimac02]

I agree with the concept of stay in higher gear as long as possible.

However, the sg is estimating FE based on the airflow and it's perceived fuel flow. But, at WOT, the engine enters open loop mode where the ECU is no longer regulating the mixture (same as when you first crank up).

My Sg appears to be inaccurate while I'm in open loop mode. It will consistently claim that I'm getting 45mpg at 19TPS until it switches to closed loop, at which point it reads 30mpg.

The point of this is:
In spite of the Sg's possible inaccuracy at WOT, IT IS STILL BEST to stay in 5th gear.

BTW Taco is doing a great job at 66% over EPA!!

[JohnnyV]

Congrats to the OP. I've got an 06 civic and my best tank so far as been 43 mpg with only driving techniques. I plan on adding a grill block this fall and possibly some rear wheel well covers. Get us updated on your progress!

[KJSatz]

I just drove home and got about 40.6 miles per gallon. 30 miles of it was city driving in a small town with lots of stop signs, but I don't think I would have gotten much worse than 30mpg there, and even if you do a weighted average the highway mpg would be like 42.5mpg. A little disappointing.

I drove about 55MPH the whole time. Actually, it was getting late towards then end, so I had a couple of times when I would accidently go too fast (nothing crazy, but once I caught myself at 63 and accelerating up a hill, and once I found myself at 67 on a level area, when I was getting really close to home). There were some times when I didn't know if I should downshift or not...it seemed like the gas gauge was falling rather quickly when I would go uphill and slow to 53-51MPH still in fifth. I started downshifting on the hills halfway through the trip. Here's a place when an OBDuino would be useful.

I think I'm going to drive 55MPH again on the way back. I'll have my tires properly inflated (they're like 36PSI right now, which is okay, but I'd like to be at the sidewall max). I'll try to figure out when I should be shifting and when I shouldn't be. I'll try to read more about VTEC-i and the "fuel efficiency cams" my engine has that I don't understand. I'm driving back on Sunday. I'd appreciate any advise.

[BlackDeuceCoupe]

Originally Posted by KJSatz

On the drive home for Labor Day I calculated over 41MPG, and everyone told me "no that's crazy...

LoL!

I've actually had ppl call me a liar - on Honda web sites, no less!

Who the heck would lie about gas mileage?!?!?

Originally Posted by KJSatz

I just drove home and got about 40.6 miles per gallon...

I'll have my tires properly inflated (they're like 36PSI right now...)

I'm driving back on Sunday. I'd appreciate any advise.

Sounds like we get about the same mileage, but 36 psi is a 'flat tire' in my book!

Forget the "sidewall max" and pump your tires up to 50 psi.

It'll be a whole new experience... believe me!

[KJSatz]

Well up to sidewall now anyway. I noticed driving around town it coasts a lot easier, which is great. I've driven about 30 miles in town, and the gas gauge hasn't moved yet....

[BlackDeuceCoupe]

Originally Posted by KJSatz

Well up to sidewall now anyway. I noticed driving around town it coasts a lot easier, which is great. I've driven about 30 miles in town, and the gas gauge hasn't moved yet....

Now you're getting it!

50 psi, dude... NOT 44 or 66... 50 psi!

It's THE magic number.

[KJSatz]

I think that the pump last time overfilled a little, or filled more than the other pumps I have used. The fill-to-click long-division method gives 47.8MPG! This was with 65 miles of city driving and then about 250 miles of highway driving. If you do a weighted average with the 65 city miles at 35MPG, the highway is over 50...but I am skeptical. Either way, I am pretty sure this trip was over 45MPG, which is totally awesome. I attribute it to the upped tire pressure and more experience driving slowly. Thanks for the help everyone! Any more ideas would be awesome!

I think I'm going to build an OBDuino too, and that will make it even better.

[BlackDeuceCoupe]

Originally Posted by KJSatz

I think that the pump last time overfilled a little, or filled more than the other pumps I have used. The fill-to-click long-division method gives 47.8MPG! This was with 65 miles of city driving and then about 250 miles of highway driving. If you do a weighted average with the 65 city miles at 35MPG, the highway is over 50...but I am skeptical...

I've thought about this a lot, and I agree! There is no control procedure, so called!

The bugaboo with all this (fill n' calculate your mileage stuff) seems to be the 'fill-to-click' procedure you use!

For instance, the angle and attitude of the car during filling can make a difference, as to how much gas you can get into it - is it facing uphill or downhill - to the left or to the right? Did you fill the tank fast or slow - and how fast or how slow did you fill it, and does ANY of this make ANY difference, blah, blah, blah...

Really, the only true measure of mileage can be averaging the results over a period of time and space - but - over how many miles do you average it - and for what length of time?

LoL!

I'm a skeptic too...

Sometimes I think we're all making a big deal over nothing - to make ourselves *feel* better about being skeptics - but I'm skeptical about that too!

[elhigh]

Originally Posted by KJSatz

I attribute it to the upped tire pressure and more experience driving slowly. Thanks for the help everyone! Any more ideas would be awesome!

I think I'm going to build an OBDuino too, and that will make it even better.

I haven't modded my truck at all except to bump up the tire pressure, and like you the results really were surprising.

College student? If you're anything like I was, the car is a locker on wheels. How much junk is riding around in your hoopy that you could remove and not have to take for a non-profit tour of the city? Every pound you save is a pound you don't have to pay to drag around.

[KJSatz]

I keep it pretty empty. Extra things I lug around are a car cover and a toolbox. On this trip up it was really full though because the guys I took up had tons of stuff. Counting people I might put it over 600 pounds of stuff.