Ridiculously horrible gas mileage 128i

[hatepotholez]

Hello everyone, as the title states I am getting some ridiculous gas mileage. From full to approx. empty(12.956 gallons) my mileage driven was only 191. My commute is a mix of city and highway, with barely any stop and go's.

Dealer states the car is normal, also there are no check engine lights.

Probable things to do/check:

1)Tire pressure, I set them all to factory specs but I can check it again.
2) Air filter(Dealer states it doesn't need to be changed, Indy states air filter is probably not the cause).
3) Clean the MAF.
4) Some fuel sysem or intake cleaner?
5) Ask dealer to check o2 sensors if the voltages are correct.


Any tips or opinions would be greatly appreciated.

[Obioban]

Any fuel smell?

[Evice]

Originally Posted by hatepotholez

Hello everyone, as the title states I am getting some ridiculous gas mileage. From full to approx. empty(12.956 gallons) my mileage driven was only 191. My commute is a mix of city and highway, with barely any stop and go's.

Dealer states the car is normal, also there are no check engine lights.

Probable things to do/check:

1)Tire pressure, I set them all to factory specs but I can check it again.
2) Air filter(Dealer states it doesn't need to be changed, Indy states air filter is probably not the cause).
3) Clean the MAF.
4) Some fuel sysem or intake cleaner?
5) Ask dealer to check o2 sensors if the voltages are correct.


Any tips or opinions would be greatly appreciated.

Your foot is heavy and you are sitting in traffic too long. lol

[andnkuhn]

Originally Posted by hatepotholez

Hello everyone, as the title states I am getting some ridiculous gas mileage. From full to approx. empty(12.956 gallons) my mileage driven was only 191. My commute is a mix of city and highway, with barely any stop and go's.

Dealer states the car is normal, also there are no check engine lights.

Probable things to do/check:

1)Tire pressure, I set them all to factory specs but I can check it again.
2) Air filter(Dealer states it doesn't need to be changed, Indy states air filter is probably not the cause).
3) Clean the MAF.
4) Some fuel sysem or intake cleaner?
5) Ask dealer to check o2 sensors if the voltages are correct.


Any tips or opinions would be greatly appreciated.

I put 1 bottle of TECHRON in a full tank every 3000 miles or so. It cleans out my injectors and seems to help my fuel mileage marginally. Maybe for you it will clean out your injectors and give you a much needed improvement. I buy mine at my local AutoZone but here is what it looks like.

http://www.amazon.com/Chevron-65740-...ywords=TECHRON

[andrey_gta]

what type of gas do you use?

[ulrichd]

Originally Posted by hatepotholez

Hello everyone, as the title states I am getting some ridiculous gas mileage. From full to approx. empty(12.956 gallons) my mileage driven was only 191. My commute is a mix of city and highway, with barely any stop and go's.

Dealer states the car is normal, also there are no check engine lights.

Probable things to do/check:

1)Tire pressure, I set them all to factory specs but I can check it again.
2) Air filter(Dealer states it doesn't need to be changed, Indy states air filter is probably not the cause).
3) Clean the MAF.
4) Some fuel sysem or intake cleaner?
5) Ask dealer to check o2 sensors if the voltages are correct.


Any tips or opinions would be greatly appreciated.

Actually that's about what I get with a heavy right foot and mostly city driving. I don't get past 200 miles per tank until I do some freeway driving.

[631twentyeighteye]

just about all highway i get 25mpg no issues, and that's not going slow by any means. Thats also with some playing around town. I get 250+each tank easily. i have an MT also.

[bmw1racer]

Originally Posted by andnkuhn

I put 1 bottle of TECHRON in a full tank every 3000 miles or so. It cleans out my injectors and seems to help my fuel mileage marginally. Maybe for you it will clean out your injectors and give you a much needed improvement. I buy mine at my local AutoZone but here is what it looks like.

http://www.amazon.com/Chevron-65740-...ywords=TECHRON

You can get a six-pack of Techron Pro-Gard at Costco for about $20, if I recall.

[andnkuhn]

Originally Posted by bmw1racer

You can get a six-pack of Techron Pro-Gard at Costco for about $20, if I recall.

The pro-gard is different than the concentrate-plus i believe. The pro-gard is cheaper. so im assuming the concentrate-plus is better? I have never used the pro-gard.

[hatepotholez]

No gas smell.

I can try the chevron additive and try using tier 1 gas stations.

I always put 93 octane.

No driving with a lead foot here, that's for sure!

Can a partially dirty fuel filter be an issue?
What about a dirty maf?

I should ask the dealer to check the o2 sensor readings just in case.

She recommended to try a fuel injection service, because the previous owner might have used 87.

The commute is 60% highway and 40% local. Barely any stopping.

[HeelToe]

Mileage on the car? I replaced plugs on my 330i (same engine but different intake) and got almost 2 mpg. I had 70k miles and replacement was not recommended until 100k. That wouldn't explain all of your problem but you may have more than one item causing the issue.

[hatepotholez]

Originally Posted by HeelToe

Mileage on the car? I replaced plugs on my 330i (same engine but different intake) and got almost 2 mpg. I had 70k miles and replacement was not recommended until 100k. That wouldn't explain all of your problem but you may have more than one item causing the issue.

Currently it has 39k on it. Was it quite a task changing out the plugs? If the previous owner used 87, and now using 93 would that have something to do with the bad mileage?

[TheSt|G]

If you are getting 14-15mpg you have a serious problem.

I drive like a complete ass whenever I can(~80% of the time) and I get 20.4mpg. The only time I was getting 14-15 MPG is when on the highway at a constant 130mph. We lose mpg dramatically going past 80mph in this car.

[Dackelone]

Originally Posted by hatepotholez

No gas smell.

I can try the chevron additive and try using tier 1 gas stations.

I always put 93 octane.

No driving with a lead foot here, that's for sure!

Can a partially dirty fuel filter be an issue?
What about a dirty maf?

I should ask the dealer to check the o2 sensor readings just in case.

She recommended to try a fuel injection service, because the previous owner might have used 87.

The commute is 60% highway and 40% local. Barely any stopping.

^^That would be the first thing to check. And check for any stored codes. your lambda value should be near 1.00 +/- 0.02% with the engine running.

What kind of tires do you have? OE sizes? And what pressures? I would also take out your air filter and see how dirty it is. The fuel filter is part of the fuel pump... and it should not need to be replaced yet. Probably around 80K or 100K miles.

You might even want to check the trans fluid and level. Also the diff fluid. It won't hurt to change those out. Changing spark plugs wouldn't hurt either.

Also what kind of oil are you using? Maybe the previous owner put something really thick in the engine?


^^^These are the things I would look into.

Dack

[hatepotholez]

Originally Posted by Dackelone

^^That would be the first thing to check. And check for any stored codes. your lambda value should be near 1.00 +/- 0.02% with the engine running.

What kind of tires do you have? OE sizes? And what pressures? I would also take out your air filter and see how dirty it is. The fuel filter is part of the fuel pump... and it should not need to be replaced yet. Probably around 80K or 100K miles.

You might even want to check the trans fluid and level. Also the diff fluid. It won't hurt to change those out. Changing spark plugs wouldn't hurt either.

Also what kind of oil are you using? Maybe the previous owner put something really thick in the engine?


^^^These are the things I would look into.

Dack

The car is at the dealer now, and I told the SA to check the O2 readings and MAF readings. They said they would run a fuel efficiency test(?). Either way I am going to clean the MAF as it looks like a common thing to do and change the air filter.

Running stock size tires, front RF tire is brand new, LF has pretty good thread on it. The tire pressure readings i'm not to sure of but I will definitely check them over. I bought a tire gauge just for this lol!

The car was maintained at the dealer, and don't see any history of ATF fluid change or rear Diff, but do see engine oil changes done at the dealer. One Indy I spoke to stated don't touch the ATF until 50k.

I might consider putting an exhaust and intake if it would help.

[Dackelone]

^^You should check/change your air filter. No telling what it looks like. BMW dealer service means nothing but oil changes and wiper blades and maybe a pollen filter and brake fluid flush at two years. Nothing more.

Plugs and air filter would be my best bet before doing any mods.

[MightyMouseTech]

Also, I see you are in NYC. Freezing temps, short trips and stop and go driving combined will give horrific fuel economy. Although, you mentioned no stop and go driving. Do you let the car idle for more than a minute or so?!?!?

[hatepotholez]

Originally Posted by Dackelone

^^You should check/change your air filter. No telling what it looks like. BMW dealer service means nothing but oil changes and wiper blades and maybe a pollen filter and brake fluid flush at two years. Nothing more.

Plugs and air filter would be my best bet before doing any mods.

I think your right, I haven't even checked the air filter. Might as well order one and put it in.

[hatepotholez]

Originally Posted by MightyMouseTech

Also, I see you are in NYC. Freezing temps, short trips and stop and go driving combined will give horrific fuel economy. Although, you mentioned no stop and go driving. Do you let the car idle for more than a minute or so?!?!?

Yea it sits for over a minute, sometimes though not often. If I sit for over a minute will it make a difference? If so ill do it more often lol!

[631twentyeighteye]

idling=zero mpg. minimal idling=best mileage. with that being said, i let mine sit in the mornings for 5-10 mins before i leave for school. I dont care what BMW says, letting oil circulate on a cold motor is better then just starting it and taking off.

[Iron Man]

Originally Posted by 631twentyeighteye

idling=zero mpg. minimal idling=best mileage. with that being said, i let mine sit in the mornings for 5-10 mins before i leave for school. I dont care what BMW says, letting oil circulate on a cold motor is better then just starting it and taking off.

I read somewhere, can't remember the source, but it stated that it is better to warm up most modern engines by driving them lightly the first few miles, rather than idling.

[631twentyeighteye]

the issue with that is that i drive .25 of a mile before i have to merge onto a highway, i'd rather let it idle for a few minutes before having to merge on a cold motor.