bsmiley

2001 LX 5MT.
I have been baffled for the last 4-5 tanks of gas
I usually fill up when I have a 1/8 tank remaining. I always reset the trip meters and check my mileage.

I filled up with needle just above 1/8 dash. Gas light off. Pump said 11.6 gallons. In the past I've had around a gallon left when light came on. Tank is 11.9 gal per owners manual.

Another time I filled up at 1/4 tank and it took 9.5 gallons. Had 348 miles.

Today it was 292 miles but read exactly half a tank. I filled up and it took 6 gallons. So 48 MPG.

Lost because it seems if I use Google maps to calculate distance when I arrive the trip meter shows right mileage. So if speedo is on, what is off?

ezone

Neighbor is adding fuel to your tank at night, causing your mileage calculations to go through the roof!

bsmiley

or the gas fairy thinks I'm living right...

Star1967

What grade do you use? I'm getting 45 miles to the gallon using 92 octane from BP with an automatic transmission. Using the trip odometer and mixed driving ranging from 15-70 miles an hour. Yesterday I filled the tank costed $18 so far I used 1 gallon 50+ miles.

cja3455

The car may be running lean, even Honda didn't rate the mpg of the car that high brand new out of the factory

ezone

If you drive it right you can beat the EPA rating, no problem.
The highway Gods of traffic and time must smile upon thee in order to do it consistently around here.

My own car was rated at about 39 hwy (which I can't even touch now going realistic interstate speeds LOL), but back when I had stock OE wheels and LRR tires I saw over 53 MPG while driving steady 45-55 MPH non-stop on flat road.

I could only manage to drive that slow going to my sisters house on a weekend when there's almost no traffic.

usajags84

Quit drafting big rigs

Actually I was reading an article on a tacoma forums since my taco is doing very good as well, someone mentioned that with the low oil barrel prices some companies are not mixing in as much ethenol which makes total sense for the increase. I ran my taco with pure gas (last summers generator gas at the end of season) and I saw a 2 mpg increase in stop and go traffic my tacoma gets about 21 mpg on highway about 24-25 on last fill up I got 24.5 mpg and it was mostly city driving with ac on full blast
(I have to having a truck for my second job) my civic is my primary I'm averaging about 32mp mpg all city with ac on full blast

bsmiley

I normally use Costco reg 87 octane.

I've been averaging 34-35 mpg since April 2014. I hardly ever run the AC.

If I'm doing pretty good on mileage I'll get to 200 miles on the trip meter about the time it starts showing half a tank on fuel gauge.

292 miles on trip meter today, gauge showed right at half. So i figured the fuel gauge was having issues. When pump clicked at 5.9 gal I figured it still wasn't full so i pumped a tad more, clicked again. 6.0 gal for 292 miles.

I always set pump to first click & stop when it clicks. So if pattern holds true, next time I'll fill up at 300 miles on trip meter & it'll take 11 gallons.

Something odd going on for sure.

ezone

300/11=27.272727 mpg
292/6=48.666

bsmiley

Now you are seeing my point. Something is strange. Maybe even though it clicked 2x times it wasn't full?

I seriously can't see how i could get 48 mpg.

The first time I had 290 miles and it took 11.8 gal to fill, i complained that pump was out of calibration. I said my tank only holds 11.9 & my gas light wasn't on yet...

ezone

Google says 13.2 gallons?

Stock 99

Oh yeah.... your car isn't averaging 48 mpg. Not a chance...

Unless your driving 300 miles in one go and even then.

My 99 Civic max 42 mpg all highway with great fuel economy habits.

ezone

https://www.edmunds.com/honda/civic/...st-specs1.html

sdaidoji

iTrader: (1)

I topped at 44MPG, but was driving from Quebec to TN, car full of stuff (moving), so it was heavy as hell - start moving and it will not stop!

bsmiley

GolNat

iTrader: (7)

^ that's odd. I thought mine was 13.2?

Now I will have to check the manual when I get home.

bsmiley

My best guess is the tank isn't actually getting full. I'm not sure what to try.

ezone

The gas tank is designed to have a certain amount of air space that cannot be filled with liquid (gasoline) to allow for expansion and vapor recovery/emissions equipment to operate.
I wonder if that's the difference in capacities? (actual vs. usable)

Is there a capacity difference between sedan and coupe?


Sorry, I don't have time to research.

bsmiley

The pic I posted is the last page in my owners manual. I didn't see a different capacity for the coupe.

0396

I have a 2012 Civic HF. The best MPG I can get out of it is 44 MPG going down hill. If you're looking for average 48 MPG, please advise how you're able to accomplish that. As a DD, car avg 35 MPG even when Honda advertise 43 +.

mikey1

this

ezone

I'm looking at owners manuals......on the Honda tech info site here....

01 Sedan is listed as (approx.) 11.9 US gallons.
17500-S5A-A35 for Japan and USA built cars
17500-S5A-A36 for Canada built cars.


02-05 Sedan fuel tank capacity is listed as (approx.) 13.2 US gallons
17500-S5A-A35 for Japan and USA built cars
17500-S5A-A36 for Canada built cars.


01-05 Coupe is listed as (approx.) 13.2 US gallons
01-05 Fuel Tank # 17500-S5A-A35


So ALL these cars use the same tanks, but ONLY the 2001 SEDAN is listed as having a smaller capacity..
I think the 2001 Sedan book is a misprint.



EDIT: Supporting evidence: and it took 11.8 gal to fill, i complained that pump was out of calibration. I said my tank only holds 11.9 & my gas light wasn't on yet...

bsmiley

Maybe there is only one replacement part now but the 2001 originally had a smaller capacity tank...? ILS does that stuff all the time.

I've run the tank pretty low before. Drove 25 miles after the light came on & she was running a little rough when I pulled into the pumps. Took 11.6 gallons. Gauge showed a little below empty.
I guess I could put a gas can in trunk and run her out of gas, see what it takes to fill the tank.
But I still suspect the tank isn't getting filled all the way. 48mpg, smh on that one.

GolNat

iTrader: (7)

My manual does say 11.9.

But looking back in my MPG log book I have put 12.5 gallons of gas in it so it is bigger then 11.9.

I don't think the gas gauge is all that great in the car.

bsmiley

I previously considered the gas gauge as accurate as any other I've had, but now I don't trust it. I always go off miles driven and how much fuel it took to fill.

I trust my miles driven since last fill up. I have never put in more than 11.8 gallons. My previous big fill had been 11.6

Usually when the fuel light comes on I fill up and it takes about 11 gallons. Most fill ups have been between 10-11 gallons.

If my tank is 13 gallons then my fuel light comes on very early.

I had changed the fuel cap last April after getting a CL code.

I suspect the cheap cap ($3.99 from Rockauto) is part of the problem. Maybe it doesn't vent correctly and I've got an air lock of some sort.
I put a Stant fuel cap on it today. It seems higher quality.

Since I filled up Sunday evening I have driven just over 100 miles. Fuel gauge shows I've used a quarter tank. I'll fill up this weekend and check my mileage. If it I'm still above 35 mpg I will assume its a bonafide miracle from heaven.

Its entirely possible Honda put a 11.9 gal tank in the 01 cars and market variables caused the increase to 13.2. Instead of paying more for a smaller tank, they would have just adjusted for the bigger tank. This stuff happens all the time in manufacturing. Going back and getting all the documents to reflect the changes is a never ending job.

bsmiley

I filled up this morning, just to see...

109.3 miles, 3.27 gallons for 33.4 MPG. That's much closer to normal. I'm still baffled by last Sunday's 48mpg.

sdaidoji

iTrader: (1)

I was baffled with the 44MPG myself, but it was the best in one tank among 3 or 4 fillups? and full of stuff on HWY only for 1200 miles and a leaky head gasket

I would recommend checking spark plug colors, just in case it's running too lean.

bsmiley

Yes, that's a great idea. It could be running lean, but it feels smooth and strong. Since this mornings fill up I've given this some thought.

My driving is very consistent. Mostly suburban. The tank that I got the 48 mpg wasn't a highway drive, it was back and forth to work, the usual stuff. The only logical explanation for that mpg is the tank didn't get filled all the way. The pump clicked 2x and registered 6 gallons but I think it should have been ~8.5 gallons.

So I drove normal route, etc this week but I did run the AC during most of my driving Monday and Tuesday. I fill up this morning and it clicks off, 3.2 gallons, 33.4 mpg and it seems completely reasonable...

...except IF it wasn't filled all the way at the last fueling (short ~2.5 gallons) then I would expect this mornings fill-up to be ~5.7 gallons.

Reasonable explanation might be that the pump clicked off and the tank still didn't get full but the fuel gauge indications have been reasonable.

A more reasonable explanation is that the pump on Sunday gave me ~8.5 gallons but only registered 6 gallons. I think this is likely what happened. I think fuel pumps aren't calibrated very often and can be inaccurate quite frequently. Few people monitor their fuel mpg, and it isn't noticed.

If my engine was running lean I'd have more indications besides one amazing 292 mile stretch at 48 mpg. The average of the last two fill ups is 43 mpg. No way.

The 48 mpg tank is an outlier that has to be excluded.

Final answer is the pump gave me a 2.5 gallon gift.

The only thing I can't find a logical answer for is why the fuel gauge showed half a tank at 292 miles. Normally its ~180-200 miles at half a tank.

sdaidoji

iTrader: (1)

Hey, bsmiley,

you know, these engines, given the right conditions, temperature, no A/C, driving style, etc, they can deliver unbelievable numbers...

just this morning, 8 miles HWY, 4 miles of mixed 45 to 40 zones

39.5 MPG



satisfied

Crower stage 1, normal AS stock sized tires

ah, If speed enough to keep engine at above 2500 RPM, I keep in gear in downhill, if less than 2500, I simply put in neutral.
Also, I rarely brake for corners. Most of them i just keep the momentum. Most of corners can be taken above the posted limit anyway

Maintenance light? that darned button died on me 5k miles ago...

bsmiley

NOW this interests me. I've been doing the neutral coast a lot lately. Usually by the time I catch the traffic at the light, I can engage 3rd and ease up to speed.

Whats a crower stage 1? How does that mileage meter work? Wired connection to OBD port?

I'm in flat coastal Virginia Beach, so not much downhill coasting.

38.6 for a work trip up the eastern shore. I'd love to hit 40mpg, just because I did it once in my 88 Civic Lx sedan (5MT of course )