Help with Low MPG!

That's why I want to diagnose the O2, since they seemed to be covered under my SULEV warranty don't want to replace parts that are covered, found out my thermostat was covered too. Can the O2 soft fail without throwing a CEL code?

This is my wing: http://www.solsticeforum.com/forum/a...-ricer3-1-.jpg UMAD???? Elevation is pretty flat no huge hills.

I've never seen my go any higher than 20mpg on the obc. Highway or city driving.

I'd be curious to learn on the o2's operation with live data during driving . Not an expert on what you should be seeing there so Im gonna watch what more knowledgble people come back with on this . Ofcoarse tire pressures and air filter condition would be the first things Id look at. Kicking it into nuetral though on down hills I would exercise caution with this however. While I don't have alot or , should say any experiance with the BMW transmissions specifically. The engine drives the automatic trans fluid pump. When you are going at a given speed say 60 mph then kick the engine into nuetral you slow the pump down. However as you coast along in nuetral the internals of the trans are still going at speed driven by the driveshadt but now with reduced pressure from the pump. In short bursts I dont suppose it will hurt but I'm tld by my friends in the trans rebuild profession not to do this . Just something to consider .

Originally Posted by gselsidi

Also, everyone please stop with your comments about MPG I asked how I can diagnose my fuel system, oxygen sensors, ect. not to get an opinion if my mpg is good or not.

sent from my ATARI sc1224

I have torque and bmwscan. They both are great in their own ways. BMWscan is wayyy more comprehensive and will give you a lot more info about your car. The torque setup is a basic ODB application for any car, but will read fuel trims. They are so cheap you can buy both. You should however fill your tank, drive it, document miles, fill again, and calculate true MPG.

Originally Posted by HiHoBrian

Attachment 493448

sent from my ATARI sc1224

Here lies the problem nobody asked for random useless comments, I asked something very specific. Great comments including one from yourself use a paper and pen to calculate mileage. Where if you bothered to read or maybe people just can't comprehend English, That I manually calculated MPG.

Originally Posted by sstackman

I'd be curious to learn on the o2's operation with live data during driving . Not an expert on what you should be seeing there so Im gonna watch what more knowledgble people come back with on this . Ofcoarse tire pressures and air filter condition would be the first things Id look at. Kicking it into nuetral though on down hills I would exercise caution with this however. While I don't have alot or , should say any experiance with the BMW transmissions specifically. The engine drives the automatic trans fluid pump. When you are going at a given speed say 60 mph then kick the engine into nuetral you slow the pump down. However as you coast along in nuetral the internals of the trans are still going at speed driven by the driveshadt but now with reduced pressure from the pump. In short bursts I dont suppose it will hurt but I'm tld by my friends in the trans rebuild profession not to do this . Just something to consider .

Yes I am awaiting for JFOJ to pop his nogen in here and help, WHERE ARE YOU JF!!! Why oh why are you not at my instant informational disposal!

Originally Posted by rudycoop

I have torque and bmwscan. They both are great in their own ways. BMWscan is wayyy more comprehensive and will give you a lot more info about your car. The torque setup is a basic ODB application for any car, but will read fuel trims. They are so cheap you can buy both. You should however fill your tank, drive it, document miles, fill again, and calculate true MPG.

yeah was thinking of torque just decided to buy a cable to run INPA

Originally Posted by gselsidi

....Another thing I noticed is everytime I park my car when I start it the next day the fuel gauge is always a bit lower then where I left it when the car is turned off. It's a level parking lot so no incline or anything. Is fuel evaporating?? What could cause this?[/B]

Have you tired using the OBC in determining how much fuel you actually have in the tank? I would take a reading when you stop for the day and take another reading in the morning. It would at least tell you whether you have a fuel loss or experiencing a gauge issue.

Originally Posted by hacksawmark

Have you tired using the OBC in determining how much fuel you actually have in the tank? I would take a reading when you stop for the day and take another reading in the morning. It would at least tell you whether you have a fuel loss or experiencing a gauge issue.

BRILLIANT IDEA can't believe it didn't cross my mind. Which menu number is that under? Thanks

That would be #6. I've attached a PDF doc that I saved the hidden functions menu to (thanks JOFJ) so you could have it handy in the future.

Be sure to share your findings. I'm curious to know how this will all resolve out. I'm also curious to find out if there is a difference in MPG between your M56 vs my M54.

EDIT: Upon further research, you may be achieving optimum MPG for your bimmer. According to fueleconomy.gov, your bimmer is rated (under the revised 2008 EPA estimate) for 17-MPG city and 25-MPG Highway. That being said, my personal experience is that you can achieve 5 - 10% better than the revised estimates.

Not sure I want to comment on this one!

Here is what I can tell you on this issue.

1. Leave the car in gear, these cars are programmed for fuel cut off under coast conditions. It actually does make an impact on fuel economy. In order for the engine to idle, it needs fuel, under coast conditions, the drivetrain will keep the engine spinning and it does not need fuel.

2. OBC mileage valves can and at times are way off. Not sure how to adjust or tweak them, but it may be possible. I would not waste a lot of effort on this as you can and should manually calculate fuel economy.

3. Not sure, but these cars were likely tested with straight gasoline and not 10% Ethanol blend fuel for fuel economy ratings??? If they were tested with non Ethanol blend fuel then the economy figures would be higher than you are expecting.

4. Given the age of the car, things like MAF, O2 sensors, DISA, VANOS, carbon build up, engine wear, restricted/clogged exhaust and fuel delivery can all work against performance and fuel economy. Something even a simple as a fan clutch that is not slipping as expected, an exhaust flap that is not opening, a auto trans torque converter clutch not working properly, or a different oil blend could lead to reduced fuel economy. Some of the items are cost effective to address, some are not.

5. Given you have a SULEV car, although a lot of things are covered via the SULEV warranty, the warranty does not really cover component degradation. So you will need to make a decision on what you are willing to replace on your own. BMW really only will cover "failed" parts and I would expect you would need a O2 sensor code for like a failed heater or an issue where the car could not pass emissions due to something being WAY out of the norm before BMW picks up the tab.

6. Fuel, I can go on about this for a long time. Readers Digest version.

a. Ethanol percentage and mix can and often is very sloppy. You can buy Ethanol test kits for relatively cheap, however, not sure how accurate they can be, but at least you can compare fuel brands as well as see how consistent the fuel you are buying actually is.

b. Search the term Ethanol Phase Separation. This will open your eyes a bit!

c. When trying to deal with fuel economy issues, there are a lot of variables. An easy variable to change is fuel station/brand to see what happens. One thing to also consider is when was the Bureau Of Weights & Measures Test/Calibration was last performed on the pump(s) you are using. Also what time of the years was the test performed. Most states require annual pump testing/calibrations. Usually there will be a test/calibration sticker will need to be displayed on the pump face. Pay attention to this and the date as well as the time of year the pump was tested/calibrated.

7. Ground temperature of fuel in storage tank. Gasoline expands and contracts with temperature. When you measure by volume, this becomes very important. Not sure if any of the newer pumps are temperature compensated, but I know in Canada the fuel is actually heated before it hits the pumps as the fuel suppliers tend to get short changed with temperature variations. On the flip side, during warmer weather, fuel will expand and you will be short changed by volume and the supplier will make out. Is this enough for you to really notice?? But the fuel suppliers do!

8. Pay careful attention to tire inflation and tire wear ratings. Higher wear ratings likely mean harder compounds and likely lower rolling resistance??

9. Pay careful attention to things like brake caliper maintenance and parking brake adjustment. Sticky calipers, hard and work caliper mounting bushings, parking brake that may not fully release may cause a bit of extra drag that could impact fuel economy.

Many of the things mentioned above may only impact fuel economy in a VERY small way, however, if you end up addressing many small items, you could see a larger improvement in fuel economy.

Some things like O2 and MAF sensors are maintenance items. They do not last forever and you may not get them replaced under warranty so you may have to pony up the cash to replace them on your own dime.

Getting some form of scan tool or software that can read and graph real time data and pay careful attention to engine temp, fuel trims, O2 sensor performance can be a big place to start.

See this thread about software and scan tools that may be informative - http://forum.e46fanatics.com/showthr...light=software

Also suggest you check out some of the smart phone apps that will help you easily log and even graph fuel economy and will allow notes on things like station, pump number, cost, date & time. The may be helpful in tracking things as changes are made to the car.

All I can say is my E39 M5 with a steeper rear gearing that causes the engine RPM to be a bit higher than stock will get 23 MPG during the summer if I say below 70 MPH. Not sure what a 325 SULEV automatic should get, but I think much above where you are currently may be hard to obtain, but it may be possible.

Just do not expect BMW to pick up much of the tab for your improvements.

Good luck.

+1 on station gas quality. Going back a year or two ago I fueled up in Carolina deep in the country on my motorcycle and within an hour the bike was having issues.

Also, I read in the manual (and common sense) that you should never run the car close to dry, as all of the "impurities" at the bottom of the tank will be sucked into the engine.

Be interested to find out ultimately if non engine conditions (tire pres, weather, etc) bring back the MPG or if the thread owner has to resort to a tune up etc.

Will find out soon enough there is nothing wrong with vanos as its brand new, disa seemed fine. My gut is telling me something with the fuel system, whether fuel is evaporating or what not. Or possibly O2 sensors even though there is no code. Been doing city driving getting about 10mpg that's way below even new EPA estimates.

Again i still don't buy this car wasting gas like a 500hp v12 car. When plenty of people have posted highway numbers in the 30s at a much higher speed then i drive at. Will keep you updated on what i discover.

I bought a dcan cable will install inpa and will monitor and see what shows up.

Originally Posted by hacksawmark

That would be #6. I've attached a PDF doc that I saved the hidden functions menu to (thanks JOFJ) so you could have it handy in the future.

Be sure to share your findings. I'm curious to know how this will all resolve out. I'm also curious to find out if there is a difference in MPG between your M56 vs my M54.

EDIT: Upon further research, you may be achieving optimum MPG for your bimmer. According to fueleconomy.gov, your bimmer is rated (under the revised 2008 EPA estimate) for 17-MPG city and 25-MPG Highway. That being said, my personal experience is that you can achieve 5 - 10% better than the revised estimates.

Thanks for this, I've always been able to get better 5-10% over the old estimates, so to barley hit new estimates makes me feel something is off

Originally Posted by csa714

+1 on station gas quality. Going back a year or two ago I fueled up in Carolina deep in the country on my motorcycle and within an hour the bike was having issues.

Also, I read in the manual (and common sense) that you should never run the car close to dry, as all of the "impurities" at the bottom of the tank will be sucked into the engine.

Be interested to find out ultimately if non engine conditions (tire pres, weather, etc) bring back the MPG or if the thread owner has to resort to a tune up etc.

I hope it's simple things like tires but I doubt it lol. I have every single gas station they all give me the same results.

maybe you just suck at driving :whoknows:

Where do you live?
What is your elevation?
Do you have a scan tool that can read real time data? If not, forget a out this discussion until you have tools to gather data.

CEL only goes on when things are really bad.

Originally Posted by jfoj

Where do you live?
What is your elevation?
Do you have a scan tool that can read real time data? If not, forget a out this discussion until you have tools to gather data.

CEL only goes on when things are really bad.

Don't know elevation, fort lee nj NYC area. I ordered a DCAN cable and going to install INPA. What other software can i run with the cable maybe PA soft? Don't feel like running a virtual machine to run inpa

Thanks

Suggest you read this thread - http://forum.e46fanatics.com/showthread.php?t=967204

You are going about things a bit unusual in my opinion.

INPA will not give you the info or tools you really need in my opinion.

You need something to be able log and graph with.

This thread will show you how you may have to attack your issue, assuming you determine your data is in fact accurate.

http://forum.e46fanatics.com/showthr...light=monitors