My 18is is consuming way to much fuel...

[MTD]

Something's wrong with mine too. If I'm lucky I get 19mpg. Completely baffled

What the hell, is this a chronic thing on 18is's? When i was resarching the best engine for me, everybody suggesting this one for mpg, now that i have this problem i find out lots of people have it as well... damn

I'm averaging 27 actual mpg, that's 60% highway and 40% local. What does your coolant gauge read, could it be an open thermostat causing the engine to think it's cold?????

Damn, i wish i had 27 mpg. It reads like it normally would i guess, when i start the car it's on the down low and it will slowly build up and stay at the half after driving. The temp sensor was also replaced some weeks ago

[gespinal0301]

I'm averaging 27 actual mpg, that's 60% highway and 40% local. What does your coolant gauge read, could it be an open thermostat causing the engine to think it's cold?????

[varg]

Something's wrong with mine too. If I'm lucky I get 19mpg. Completely baffled

[MTD]

I assume yes, i just put km/l into google and it transferres it to mpg for me.

I have been using this site for reference http://www.calculateme.com/cGasMilea...rsPer100km.htm

[MVincken]

I assume yes, i just put km/l into google and it transferres it to mpg for me.

[MTD]

Guys, just one thing, in this thread we all are talking US MPG right?

[MTD]

Is your wheel alignment in spec? This will definitely cost you mpg to some degree.
I also agree that tire pressure makes a huge difference as I've seen up to 2 mpg loss due to low pressure (not flat). It's also free to refill tire pressure at most gas stations so why not stay on it and save $ every fillup.

Good tip, they should be fine but i will check them tomorrow nonetheless

Tyre pressure is indeed the first thing i should look at. Atm i´m driving with 2.3bar in wintertyres.
wheel bearings are the second, try to jack up the car and spin the wheels. backwheels can spin a little harder than frontwheels due to the diff, but frontwheels should rotate almost free.
if the wheels aren´t spinning freely, check your brakes, and if that´s not the problem then your wheelbearing is bad (but normally you hear a whining sound when you´re driving)
the rest of what it could be is your drivertrain, try finding another cheap differential and look for results.
other things to check are your AFM, filters, sparkplugs and compression.

thank you the tips, i'm also going to check the wheels and brakes

[MVincken]

Tyre pressure is indeed the first thing i should look at. Atm i´m driving with 2.3bar in wintertyres.
wheel bearings are the second, try to jack up the car and spin the wheels. backwheels can spin a little harder than frontwheels due to the diff, but frontwheels should rotate almost free.
if the wheels aren´t spinning freely, check your brakes, and if that´s not the problem then your wheelbearing is bad (but normally you hear a whining sound when you´re driving)
the rest of what it could be is your drivertrain, try finding another cheap differential and look for results.
other things to check are your AFM, filters, sparkplugs and compression.

[mjimport]

What does toe and caster mean?

Is your wheel alignment in spec? This will definitely cost you mpg to some degree.
I also agree that tire pressure makes a huge difference as I've seen up to 2 mpg loss due to low pressure (not flat). It's also free to refill tire pressure at most gas stations so why not stay on it and save $ every fillup.

[MTD]

I would get 32MPG

oh yessssssssss

please also report if you could fix the problem. I also intend to get new wheels maybe in the beginning of next year, but the diff was something i only was going to change more down the line. Hope that's not it..

[bmwman91]

21MPG is poop for these engines. Back in 2008-2009, I would get 32MPG when I was commuting and actually trying to get good mileage. That is 32MPG calculated by dividing the trip odometer by gallons at the fuel pump, so actual 32MPG.

For whatever reason, if I look at my mileage since about 2010, it just decreases linearly and nothing that I ever replaced or fixed ever really helped. I still have not put my new coolant temp sensor in, but it sounds like it might not be the issue. Readings from my wide-band O2 sensor seem to indicate that things are running properly at stoichiometric.

So, maybe it is in fact a dying diff or bad wheel bearings. Sadly, those are sort of expensive and involved to replace. I will be replacing all of those items in a month or two as part of my prep for autoX in 2016 (scored a Quaife 4.10 LSD on here a little while back!)...I will report back if it help anything in my case. The small case 4.10 LSD I have in there now makes a lot of noise.

[MTD]

14" standard bbs wheels. They were aligned on a wheel house on the machine a week ago, they are alright. What does toe and caster mean?

i was really hoping to get better than 21mpg... Fuel efficiency was the main reason i chose the m42 over the other engines

[d_elson0]

Alignment/toe/caster? Tire pressure. What wheels you have? Wheel bearings. Knock out the simple things first like prior posts mentioned. 21mpg still ain't too bad, but can be better

[MTD]

Hardware is ok. All wheels are ok.
Oils have been changed about 1/2 months ago, almost after i bought the car

[MVincken]

hmm, yes i was more talking about percentage of oxigen in the exhaust gasses.

how is the rest of the hardware of the car?
try to jack it up and check if all the wheels run free
when is the last time you changed your motor/gearbox/diff oil?