MPG Questions
 

Hey guys, so I did a Tune up on my (auto) 2000GS.
It shifts better but i feel like it runs more sluggish and I think im getting less MPG.. I get currently 300km/ tank.. Aprox $40. I went to MTL this weekend and moth trips only got me 400km/ tank on ALL HIGHWAY.. any comments?

Someone told me cuz my rims are bigger LMAO! but honestly i got waaaaay more from my 3.0cl VTEC before it was totaled and i only spent about 10 more a tank..

It is probably because your rims are big. It definitely fucks with your MPG considering your rims are 3" bigger then an Integra recommends. If your car is running mechanically fine.. and you said you just re-tuned it.. which I'm guessing means cleaned it out, checked whats going on in there and did some maintainence.. you should be getting closer to 400, atleast I was and my Teg was a 94 auto

My teg has 17's on it before and I didn't notice much fuel milage decrease... What do you mean by tune up? What did you do?

It must be your rims. I remember I used to get maybe 400 or so if I was lucky with my 17's, but not all that much highway in that.

Now with my hammerheads and 205/50/15's I got 530 km last time I filled up and went for a highway trip.

The size of the rims doesn't have as much effect as the mass of the rims.

Super lightweight 17" rims may yield the same mpg as stock 15" rims. But heavy-ass 17" bling-bling rims will hurt mpg.

You can generally say that every extra pound your rims are, it's like 10x the weight because of rolling resistance.. I don't know how it works out like that, nor am I a physist.. but that's just word of mouth and research lol.

P.S. Also, this is probably the reason your car feels sluggish as well. Try putting your old acura rims back on and see if you notice a difference. I bet you will.

It's not so much the rolling resistance, that has more to do with the tire itself.

It's the mass of the rim and the fact that it takes more energy to accelerate and spin that mass up to speed.

To end the debate over which is more important tire or rim weight, look up the weight of your rims here and compare them to stock sized ones. Unless they're lightweight racing wheels, you're likely going to see at least a few pounds more in weight PER rim. As mentioned before, this, combined with the weight of your tires, will have a profound effect on yor mpg and also acceleration. Some may say that yes, with a lower profile tire you don't have as much weight in tire but you can't tell me that this cancels out the increased weight of the wheels.

Here's the list mentioned earlier. http://www.wheelweights.net/wheel-weight-weight.pdf

Just my 0.02.

-Dave

I still ask what you did for the tune up... Regardless of the rims being heavier or not, it shouldn't attribute for that kind of fuel mileage. I had 17x7's on my car, that weighed more than my stock rims by about 4 pounds each. I did notice a little less acceleration, and about 40-60km's less in fuel mileage. But I still could get around 450-500kms versus my previous 500-550 kms.

That's for sure, that's about the difference for sure. Was about the difference for me as well. The really low mileage he's experiencing is likely a greater problem than the heavier wheels, despite how much they contribute.

Maybe we all forgot to consider driving style? If you're constantly bootin it then regardless if your cars had a tune up and regardless of your wheels if you're very leadfooted your mileage will suffer greatly.

+1
Any info on the tune up? (was it just a generic "spark plug + oil change" tune up?) Were your valves adjusted? Was the throttle body cleaned?

There's so much that can affect MPG- the gas you use, excess cargo weight (maybe from your trip), driving habits...

Also remember that the fuel gauge is an unreliable indicator for gas mileage-

Want to accurately figure out your average gas mileage per fill up?

1. When you pump gas, pump it to full (I pump it until it shuts off on me once)
2. Reset your trip odometer, and drive around until you need to fill up again.
3. Pump again and this time, find out how much gas you need to pump to fill the tank (its on your gas bill or station pump)
4. Check the odometer for the number of kilometers driven, divide the Kms by the number of liters of gas pumped, and that way, you can get your mileage in km/L

http://www.fueleconomy.gov/feg/noframes/15642.shtml
If you're within 10-12 km/L, you're up to spec...

okok wow thanks guys... soo here is the scoop.. i have 18x8's . they are light weighted momos and low pros with a 30wall.. my "tune up" was a timing belt plugs and wires. i boot my car most the time.. however when i dont i still get 300km/tank lol. I just came back from mtl (510km) hwy drive and needed to fill up at 400. ALL HWY. I smell gas sometimes like its burning rich but i passed my emissions with ease b4 i did the timing. I always fill up till it clicks never over. i 50/50 use the 94 and reg. I change oil every 5000. filter is clean. ... and like i said i always get 300km/tank

correction... i dont smell gas when driving.. i smell it from my muffler.

It might be because your car is automatic, my teg only ran about 300-350 KM per full tank and it was automatic, passed emissions too... but I always thought it may have been running rich as well.

ok, OP: you're wasting your money and quite possibly contributing to poor mpg by using 94 octane in a stock b18 non-vtec. It was designed to optimally run on 87/89 octane. Do not be deceived. All higher octane does is resist detonation, meaning it takes more energy to ignite it. If the heat and compression is not high enough, it will not be completely burning, meaning you will not be getting all the potential energy/power from the fuel. Basically, it can cause your engine to burn more fuel and make less power.

There is no benefit what so ever, to running higher octane in an engine designed to run on lower octane.

Try running straight regular 87, drive the car the same, and I bet your fuel consumption will improve.

ill give that a try, i know what your saying. but i highly doubt that its the gas doing this. I say that cus i went for a while without it then decided to use it a couple times for the cleaning purposes.

It dosn't clean anything. In fact, as a result of incomplete burning, it could be junking up your engine with deposites.... :(

Run a can of seafoam through it to clean it out. lol.

seafoam is? lmao

i was going to say.. is there anything that cleans my engine and cat?

Click here: http://www.seafoamsales.com/motor-treatment.html

There's even a how-to video there.

looks good.. my buddy here did it.. and actually told ma about it but forgot lmao. ill try it out. Anything else i can do?

You say you hav 18x8 rims. typical stock rims for a civic or integra are 6-7" wide. yours are 8" wide. What size (width) tires are you currently running?

215/35/18 i believe. love em.. i know thats the typical size as u mentioned and everyone said these wouldnt fit. but they do and give a nice modern look to my ride. plus the grip is amazing. although i dont think i can lower it

Thats a bigger rim/tire diameter overall from stock.... that also could be causing the fuel mileage issue.....


So it seems you have a few things against you....

- 94 octane (yes it does contribute slightly to decreased gas mileage)
- Larger rims/tires
- Possibly running rich
- Plus myths say that standard cars (because of less horsepower drawn away from the tranny) get better mileage than autos....

-Your vtec goes BWAAAAAAAAAHHHH (often) :giggle:

if he's running 94 thats why it smells like he's running rich ^^^ drastically incomplete combustion

what oil are you using? i've heard of that being a contributing factor.

and i've heard some horror stories about seafoam... i would research the hell out of it before you run it through your car if i were you.

Arent you running 18 inch momos on your car? and using 94 octane? Man youre doing overkill

Ive heard mixed reviews. what have you heard?

Vida - yes 18's n the 94 i used to run mainly when i was going on a hwy drive. like my montreal missions.

Yea i recommend not to use it. For me at least. I used 89 at shell and i got 480 to the tank. I felt rich one day and put 91 and i got 420 or less. So for you doing 94 its just way too much and its a waste of money and gas.

As for the 18's....i get what youre saying that it gives the car a modern look...but really thats for bigger cars. Tegs are small all around and giant 18's make it look like a boat, but a really weird boat. PLUS its just killing your suspension and gas mileage. I suggest switching to a 16 or 15 inch, car will look nice and low, wont look like a boat, it'll feel nicer and your suspension and gas consumption are saved

it most def does not look like a boat, check out my pix. or come to the meet. a few of the guys have seen it a few weeks ago. As for fuel.. yea im gona take it back in and see if there is anything my mechanic can find.. the seafoam makes sence but i wanted to know if there are other products that can clean the crap out of my car

Hell. you know what though. Try this for 1 tank. If you have any smaller rims around, from 14-16 inch. Fill up your tank, and drive with the small rims until your tank is empty. Then come and tell us what the mileage is. If its still bad then its a problem. But if its back up where it normally is for tegs (450+ kms) then you found your problem. It'll save you the trouble of doing something like Seafoam.

very truuu. I will try that but my stock rims have winter tires lol. theyre gona melt in this LAVA we call summer weather. lol

dont bother. just correct your gas, dont drive so hard, and see what you end up with.

No sense in putting your smaller rims on, cus your gonna keep your current rims on regardless right? hell, if those are what you want, then you just gotta live with the gas mileage :)

yea if i put my old rims back on it would be only for testing purposes. I am most def not riding on stock rims in the summer lol

Alright, now let me get this straight... you guys all pump 89 or less octane in your ride, and you get BETTER mileage? Hmm... so let me ask- where the hell do you guys pump your gas, because you all probably found a place that has very little ethanol in their regular and mid grade gas, and that, imo, is harder to find than a rust free DA...

This is my understanding of fuel mechanics and chemistry. I may be wrong, and if I am, I'd appreciate it if someone were to point out where I've spoofed.

Theoretically, 87 octane gas is supposed to give better mileage:
- n heptane, a straight chained hydrocarbon (no branches), is found in larger quantities in 87 octane gas than in 91 octane gas (remember, a gas with straight n heptane has a 0 octane rating). Needless to say, a straight chain hydrocarbon isn't that compact- meaning that it has a lower melting and vaporization point- ideal for fuel injection engines, which must convert the gasoline into a vapor before initiating combustion. (Why vapor? well, try burning a log of wood and sawdust- the log will burn slowly, the sawdust will literally explode- its the surface area of the molecule that determines combustion. The same applies for molecules, n heptane can easily separate into a more vaporizable form, easily initiating combustion.
- 2,2,4 trimethyl pentane (isooctane), has secondary and tertiary carbons present on both ends, so due to a higher number of carbons, and a more compact structure, it has a much higher melting/vaporization point than n heptane. Thus, it is much harder for fuel injectors to vaporize isooctane for combustion- small droplets with less surface area and more fuel results per burn, yielding an incomplete burn.

So why, when I pump 87 or 89 octane, do I get less mileage? (last tank I got 12.1km/L using 91- the 89 brought it down to around 10km/L (average of 4 fill ups). I have a 91 integra RS, 1.8 L non VTEC engine, stock timing.

Its in the ethanol. Compared to n heptane and isooctane, it is hard for ethanol to vaporize. Despite ethanol being a smaller straight chained molecule, ethanol has an OH group, which enables it to form hydrogen bonds, thus drastically lowering vaporization.

So although the n heptane slightly increases vaporization and mileage of the 87 octane, the addition of 10% ethanol in the gas will lower it (unless the ethanol molecules are evenly dispersed, thus reducing the chances of the ethanol molecules in bonding with each other).

***I currently use ethanol free Shell 91 octane- I tried the ethanol laced 89 and 87 stint for a month or so, and I didn't like it. I absolutely wish that a gas station that sells ethanol free 87 gas would open up, but now with Ontario Ministry of Environment mandating a push for up to 15% ethanol in the gas... soon the ethanol free 87 of yesteryear will be harder to find than crack!***

I cant answer that but i want to say that i get about 7.5km/L and 10km/L hwy! sooo bad. :( gona try synthetic on my next change.

I agree with Vida, it would be a good idea to test it out. Worst comes to worst.. you drove for 2-3 days with regular rims but atleast you'll know if your gas mileage is affected by your rims.. (which I think it will be) and as everyone has said, bigger rims = less mileage and not recommended for integras.. but we can't argue with the style you want for you car, so if thats the rim you want then all the power to you.

I use castrol syntec- to cut down on the pricing though, don't buy it in Crappy tire- there's a lot of people on Craigslist who sells it in bulk- I got 4 4.4L jugs for 90$.
There's also amsoil for 10$ a liter if you're willing to spend 600$ and buy 60 bottles...

Oil has a pretty long shelf life, so stocking up for a couple of years ain't a bad idea...

If all you do is daily regular driving and have a non-vetc lower revving engine, don't waste your money on full synthetic oil. You won't notice a difference. What is more important then the type of oil you use is that you change it regularly.

You have many factors acting against your fuel consumption: 94 octane gas, heavy 18x8 rims, wider 215 tires = higher rolling resistance, larger then stock overall wheel diameter, and auto transmision.

You can't change the transmission of course, but you can change many of the other factors and see what kind of effect they have on fuel consumption. All those things in combination can have a huge impact on fuel consumption.

You make some very valid points. And thanks for posting this up. Was very interesting to read. :)

You must also take into account the compression ratio and conditions of the ignition and burning in a given engine.

As I sated before, an engine designed to properly run on 87 will not run properly on 94 and even may have issues running on 91 because it can't burn the fuel completely and efficiently.

It is possible for severe build up of carbon deposites on the piston and combustion chamber to shrink the volume of the cumbustion chamber when the piston is at TDC enough to increase the compression ratio slightly. It has been observed that this increase in compression is sometimes enough to cause detonation (pre-ignition or knocking/pinging) while using regular 87 fuel and by switching to 89 or 91, the fuels higher resistance to detonation allows the engine to burn the fuel more completely, thus better fuel mileage.

Does this mean maybe your engine has excessive build up of deposites on your piston/cumbustion chamber? I don't know. But its' a possibility that could partially explain what you are experiencing.

Also, other things like air temperature, humidity etc... will also have an effect on fuel consumption with regards to the condition of your engine and the type of fuel you use.

There are many variable factors.

Hmm- compression ratios... I never really thought about that. I admit that I"m not too knowledgeable about engine mechanics in general- and I would like to learn... "howstuffworks.com" just doesn't cut it anymore :(

As for carbon build up- I do admit that when I cleaned out my throttle body, I found a lot of soot- the car drove like a champ and the erratic idle was fixed- I believe this strongly suggests a lot of carbon build up in the engine...

To the OP- What exactly did you do for your tune up?

I agree with what others have said about the large 18 inch rims, but apparently the OP has just noticed a reduction in mileage and oomph after the tune up.

Hey guys, so I did a Tune up on my (auto) 2000GS.
It shifts better but i feel like it runs more sluggish and I think im getting less MPG.. I get currently 300km/ tank.. Aprox $40. I went to MTL this weekend and moth trips only got me 400km/ tank on ALL HIGHWAY.. any comments?

Now assuming that he already had his 18 inch wheels on before doing the tune up, and he didn't feel the power reduction before, the culprit must therefore not be the wheels, but something else...

thanks for all the info and support. great to read. I will try a better oil. lower grade gas. and then maybe some sort of cleaner ( seafoam or w.e ) but it may just be the wheels and the auto tranny... does anyone else here have an AUTO?? if so how many km/l do u get? or km per tank...

I told you, my auto got 350KM-ish to the tank.

I was auto, a 95 DC, with 293,xxx kms. I got 450 a tank ....i ripped it all the time so if i sailed i wouldve gotten alot more . On 89 octane at shell only

See what 15's do ;)

interesting. lol maybe since my window doesnt work the car doesnt want to run nice lol. ahhh well doesnt matter too much right now.. but if u got 350 and 450.. those are big differences.. i boot mine everywhere and get 300.. i tried driving easy to see how many k i get but its soo hard. lol

My dad gets around 450km on his 96 integra auto per fill up with 89 octane.

Last time I let my tank run on empty, I got up to 520 kms on my 91 integra auto, running 91 octane (I also use a mix of 110mL acetone and 70mL xylene for every 50L fillup, but that's besides the point...).
Now I never run my fuel tank to empty- half way and I pump (water settles in the bottom of the tank, and its really not particles and debris that gets through the fuel filter, but water).

I never tried out the seafoam (heard too many mixed opinions on that one)- but I definitely recommend throttle body cleaning.

UPDATE- after I did the TB cleaning for my dad's teg- he told me now that he's at 370km with a bit less than 1/2 a tank to go... damn he just might beat my DA's mileage :S

Well to give you some more ideas, I'm pretty sure my teg was running rich, it barely passed emissions (has an old ass cat.. could also be eatting fuel mileage.. ) but it was completely stock with 220xxxKM, with regular Acura 5 stars on it. So if you're getting less than my rich running teg.. there must be something up in my opinion.. I drove pretty hard on it too and still managed to get 320-350 per tank. I used only 87 octane.

Well we know your problem he way you drive is way to aggressive we saw your driving habits when you were leaving yesterday. Take it easy and you will def save on gas lol.

haha yea but 300km/tank AT MOST.. i dunno about that 1.. i used to kill my 3.0cl vtec and only get about 50km less then driving it normal per tank... my friend was getting like 550/ tank and got to mtl on one tank when he drove.. m/t 95 ls.. mines a 2000...

for some reason you still havent said what went down in your tune up lol. THATS IMPORTANT TOO :)

i did.. just timing belt.. plugs.. wires.. water pump.. oil change.. just the basics.. nothing else ... but i dont know if i was getting better fuel consumption before.. i think i was.

Maybe your timing is slightly off. That could cause worse fuel mileage and sluggishness.

yea im gona take it in to the doc. and see what he thinks.
booked for tuesday.

So moral of the story is....get the timing fixed if its bad, stop ripping it everywhere, and get 14-16's ;) And you'll be amongst the 500km/tank crew

downsizing.... nah id rather get a bigger car. ripping it.... maybe if it didnt need to be ripped to get the acceleration im used to..timing checked... most def! 500k. im praying lol

I usually get 500 plus per tank and 600 plus doing highway driving during the school year. I have a MT and shift at around 3k-4k rpm. Before I got some of my upgrades (intake, exhaust, etc) i was getting 500 max.

im hoping for that. ill see what i can do .. i wasnt able to get to the mechanic again