[HTMBmw]

I don't know where to post this but I was wondering if there any solution...

2 weeks ago I went to took my 07 328xi for my first maintenance, got air filter/tire rotation well at least that what it say on the paper... The mpg monitor been staying accurate from 19.2mph for like 5k miles, but it been dropping a lot to 16.1 and 16.2

The 328xi is like 17/25 but what the hell I drive freeway more then urban

[John 070]

That happened to me after the free maint ended, and I changed my air filter with a mahle knecht. If I were you I'd get a new air filter over the web, and put it in yourself. If your mileage goes back up, you know not to go to that dealership again.

The other possibility is you haven't got enough experience (data) to make your readings reliable. When mine dropped, I drove the same route to work for 3 weeks. Then I decided it was time to do something and my lowered mpgs were valid...

[Tom K.]

Originally Posted by John 070

The other possibility is you haven't got enough experience (data) to make your readings reliable.

+1. Is the OBC MPG reset at every fill-up? Has the OBC been checked for error and consistency by manually calculating true miles traveled divided by gallons used over multiple fill-ups? Could there be any other other factors such as tire pressure, brake drag, etc. affecting mileage?

Tom

[cleex024]

damn my car started to feel a little funny and my mpg dropped hard for some reason, but damn you guys are getting crappy mpgs lol.

when im cruising on the highway goin 60 my mpg was around 35, but then i started to run it hard and something happened and when i cruised at 60 last night and it was consistently at like 30-31.

so i went ahead and switched maps on my cobb and seems like it did the trick but we will see...cuirsed this morning at 60 and got around 35 mpg again.

[cleex024]

oh yeah and i got some weird codes too something like h3100, hh2a87, p2f4a, and the normal p2aaf

could someone tell me what the first 3 codes are? i searched for them but didnt get a true fix for these only the definition.

[ctuna]

I wonder if they screwed up your MAF Sensor.
I would take that air filter out and have a look at it and or clean
the MAF Sensor and reseat the connector to it.
Also do you reset your mpg's at each gas tank or was that
cumulative number if you don't I would wait awhile before
getting exited as its and average.

[E90Company]

Originally Posted by m3alabama

wow 60 on the freeway is a turtle. I keep it at 70 for best mileage because there is a point where a lower speed is not necessarily your most efficient speed based on many factors. You may be surprised that 70 provides the same or better mileage than 60

True

[cleex024]

Originally Posted by m3alabama

wow 60 on the freeway is a turtle. I keep it at 70 for best mileage because there is a point where a lower speed is not necessarily your most efficient speed based on many factors. You may be surprised that 70 provides the same or better mileage than 60

lol...i dont drive at that speed but 50-60 is the most efficient so thats why i test at 60...my minimum speed is 9 miles over the speed limit whether there is police or not. so seems like 9 miles is ok to pass officers without getting pulled over here in va beach.

anyway when i do cruise at 70 my mpg is around 32 and at 80 its around 30 and at 100 its like 24 lol

[Blubaron79]

Originally Posted by cleex024

damn my car started to feel a little funny and my mpg dropped hard for some reason, but damn you guys are getting crappy mpgs lol.

when im cruising on the highway goin 60 my mpg was around 35, but then i started to run it hard and something happened and when i cruised at 60 last night and it was consistently at like 30-31.

so i went ahead and switched maps on my cobb and seems like it did the trick but we will see...cuirsed this morning at 60 and got around 35 mpg again.

Carbon build up was killing my 335. Much better after I had the intakes cleaned.

[HTMBmw]

Well I have pumped 3x time each time is like 11 gallon around 55$-60$ from where I lived...zzz i never reseted anything other then when my low tire pressure turn on... And my check engine light soon has been on... I find to ignore it because I took to BMW dealership and they say they gotta do system update and asked for like 300$... Other then that all I got info

[chromisdesigns]

Originally Posted by HTMBmw

Well I have pumped 3x time each time is like 11 gallon around 55$-60$ from where I lived...zzz i never reseted anything other then when my low tire pressure turn on... And my check engine light soon has been on... I find to ignore it because I took to BMW dealership and they say they gotta do system update and asked for like 300$... Other then that all I got info

And he wonders what happened to his MPG? Geez.

[mike3000fl]

Originally Posted by HTMBmw

The mpg monitor been staying accurate from 19.2mph for like 5k miles, but it been dropping a lot to 16.1 and 16.2

MPG monitor should show MPG, not MPH.

Are you sure you are looking at the right menu? One is average speed, the other is average MPG.

Best thing you can do is this.... get on the interstate, get to 55 or something legal and hit cruise. While cruising reset the average MPG meter. it will show your current MPG and keep updating. After a few minutes of driving on flat ground, while on cruise, you will have an idea of your MPG. If you hit the gas or slow down and speed up or go up or down a hill it will fuck it up.

[shata]

Originally Posted by m3alabama

Wow that is worse than my m3. So much for the gas mileage arguement. My city/highway average with more city is 17mpg. Highway average is 24mpg.

I don't see why people think the m3 is a guzzler if it has similar mileage to the 3xx

Depends honestly on alot really, My 330i runs 33-34mpg on highway (55-65mph depending on speed limits). I had over 1/4 tank left on 380mile trip.

[shata]

Originally Posted by mike3000fl

MPG monitor should show MPG, not MPH.

Are you sure you are looking at the right menu? One is average speed, the other is average MPG.

Best thing you can do is this.... get on the interstate, get to 55 or something legal and hit cruise. While cruising reset the average MPG meter. it will show your current MPG and keep updating. After a few minutes of driving on flat ground, while on cruise, you will have an idea of your MPG. If you hit the gas or slow down and speed up or go up or down a hill it will fuck it up.

+1 thats how you do it.

[mike3000fl]

Here's my best. 600 something miles to empty...


no trickery or shenanigans.

[HTMBmw]

Yeah I meant mpg of course not 19.2mph my bad...damn 600 miles all highway I assume idk what's going on... If anyone know a local BMW service that gives free diagnostic in local Houston tx area I would really appreciate it

[mike3000fl]

yea all highway, driving from up north to FL and back.

anyway. you said the shop did the air filter.

since you are having a problem it is not unrealistic to think they fucked something up and unmetered air is getting past the MAF (mass airflow sensor) somehow.

when you change the air filter (not the same as the microfilter) you unhook intake parts, if they aren't connected right you have a leak.

the mass airflow sensor measures the air getting sucked in the car so that the proper ratio of fuel is injected for optimal performance and gas mileage.

if air is sneaking in after the MAF, then it isn't measured and the ratio is off, and your mileage sucks.

take the intake apart and reassemble, make sure the filter is in right, maybe clean the MAF with an aerosol MAF cleaner from autozone. then put it all back together.

maybe when they did the filter they dropped the part of the airbox with the MAF. something had to of happened.

[HTMBmw]

Anyone?