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Old 03-02-2013, 04:02 PM   #1
gselsidi
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Help with Low MPG!

Hello,

Long story short replaced my thermostat now I went from 20mpg to 25mpg, 90% all highway!! still very low with my driving habit and calculations.

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?

When I use the instant consumption menu in OBC, while driving on the highway, I estimated an avg of 5-7l/100km which is about 40-58mpg! So lets go even below those estimates and avg it a very low 35mpg highway, im doing 90% highway driving and with manual calculations I'm getting 25mpg. Is the OBC consumption wrong?

I bought a cable to run INPA will get it soon, I have no lights on the Dash

Thanks

PLEASE READ BEFORE POSTING RANDOM THINGS, NO ONE IS ASKING OPINIONS IF MY MPG IS GOOD

Last edited by gselsidi; 03-03-2013 at 12:34 PM.
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Old 03-02-2013, 04:10 PM   #2
csa714
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Fuel theft? No lock on the tank.... or does someone have an extra key?
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Old 03-02-2013, 04:11 PM   #3
gselsidi
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Originally Posted by csa714 View Post
Fuel theft? No lock on the tank.... or does someone have an extra key?
no lol. what are they doing stealing a quarter of a gallon?
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Old 03-02-2013, 06:18 PM   #4
em73876
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25 mpg is good for our cars. I get 19-20 mpg (manual calculations) with conservative driving. But then again, my OBC has never claimed 40-58 mpg. Sorry, I don't have any input on scanner options...
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Old 03-02-2013, 06:36 PM   #5
gselsidi
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Originally Posted by em73876 View Post
25 mpg is good for our cars. I get 19-20 mpg (manual calculations) with conservative driving. But then again, my OBC has never claimed 40-58 mpg. Sorry, I don't have any input on scanner options...
I'm sorry I def. don't buy that it's good when EPA calculations are 28mpg highway. I'm getting 25mpg using neutral on downhills and neutral at stop lights which adds 2-3mpg. to my total. In reality I'm down to low 20's.

I've always been able to achieve 2-3 mpg over epa all the time with my cars. Like I said my ODB is also reporting much higher numbers.
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Old 03-02-2013, 06:50 PM   #6
gselsidi
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http://www.fueleconomy.gov/feg/Find....hicle&id=21555
http://forum.e46fanatics.com/showthread.php?t=131415
http://forums.bimmerforums.com/forum....php?t=1832221

These are some numbers, peoples mpg is in the 30s driving 70-80mph I'm driving 45-60mph there's no way I'm getting mpg in low 20's, and it being normal.
One of the links for MPG shows 90% stop and go 10% highway averaging 24mpg.

Unless I need to just drive faster?? lol

Last edited by gselsidi; 03-02-2013 at 06:54 PM.
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Old 03-02-2013, 07:03 PM   #7
em73876
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I used to knock my old Jeep into N when rolling down long hills... Might not be true, but someone told me using neutral down hills and at stops actually hurt mpg. Don't ask how or why because I don't know the science behind it, but I do remember it was pretty convincing when it was explained to me. I always thought that higher revs meant lower mpg... Guess I was wrong. When I'm feeling cheap (or feeling guilty from wasting gas for a bit of fun in the mountains) I find myself watching the mpg needle instead of the mph.
Also, I read somewhere (maybe the owners manual) that the OBC doesn't take into account fuel consumed at a stop when calculating avg mpg.
As for your gas gauge dropping over night, might be a bad sending unit in the tank. If it is, I wonder if that might change OBC calculations. Then again, probably wouldn't cause the drastic change your'e reporting...
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Old 03-02-2013, 07:42 PM   #8
gselsidi
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Originally Posted by em73876 View Post
I used to knock my old Jeep into N when rolling down long hills... Might not be true, but someone told me using neutral down hills and at stops actually hurt mpg. Don't ask how or why because I don't know the science behind it, but I do remember it was pretty convincing when it was explained to me. I always thought that higher revs meant lower mpg... Guess I was wrong. When I'm feeling cheap (or feeling guilty from wasting gas for a bit of fun in the mountains) I find myself watching the mpg needle instead of the mph.
Also, I read somewhere (maybe the owners manual) that the OBC doesn't take into account fuel consumed at a stop when calculating avg mpg.
As for your gas gauge dropping over night, might be a bad sending unit in the tank. If it is, I wonder if that might change OBC calculations. Then again, probably wouldn't cause the drastic change your'e reporting...
I don't know what that someone explained to you but from personal experience i always get better mpg with neutral. Think about going down hill you will have to use gas to maintain speed because of engine braking. Also at stops drive is feeding gas to your car to make it move. I mean i don't know the exact science but like i said from countless of personal tests i always got 2-3mpg better.

Is there a way to diagnose sending unit with inpa? I just bought the cable for it. Also, i was using instant consumption on the highway not avg.
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Old 03-02-2013, 09:13 PM   #9
ElrichMeister
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25 is really nice, my OBC reads 20.2 but i have a heavy foot and the M56 is a slow car. I generally just reset my trip meter every time i fill up and then calculate how much gas i used divide the mileage by that. The OBC is fairly accurate. I drive about 40% street and 60% highway.
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Old 03-02-2013, 09:29 PM   #10
gselsidi
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Problem is i have a light foot and drive slow and i get around 20 i only get 25 using neutral which is like cheating when comparing mpg
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Old 03-02-2013, 09:48 PM   #11
HiHoBrian
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Use a pen and paper to calculate ACTUAL mpg. Not the OBC. Also,your car is 8 years old. Actual mileage will vary based on the level of wear on the engine,tranny,tires and everything else.

sent from my ATARI sc1224
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Old 03-02-2013, 10:19 PM   #12
gselsidi
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I manually calculate mpg, i only use the odb for instant consumption when driving
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Old 03-02-2013, 10:47 PM   #13
wildirish317
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I hate to say this, but get a Honda if mpg is your primary concern. If high mpg BMW is your primary concern, get a 335d. Why did you buy a BMW?
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Old 03-02-2013, 11:03 PM   #14
gselsidi
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Originally Posted by wildirish317 View Post
I hate to say this, but get a Honda if mpg is your primary concern. If high mpg BMW is your primary concern, get a 335d. Why did you buy a BMW?
MPG is not my primary concern its my primary concern when it doesn't get proper mpg. I got because I wanted one, why does it matter why I got it? Can't afford a 335D
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Old 03-02-2013, 11:08 PM   #15
tks
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25 is fine highway driving.

if you're always driving at 55mph without braking/accelerating and always in cruise, you can get 28.

i've done a few trips, where i would reset my mpg gauge, put cruise at 65-67, and get in 27-28 but this is slow ass driving.

as far as your myth on coasting into neutral and helping your car save gas, you are wrong. the ecu knows when you let go of the gas and if you are in gear it will stop delivering fuel, so keeping it in a higher gear (lower revs) on a downhill will "turn off" your fuel pump.

think about this, in order for the car to be in neutral... there has to be fuel being pumped but this is not the case when you coast down a hill in gear without gas pedal.. anyways your computer knows!! i am late to sleep

if you don't believe me, go into hidden obc, i believe its the 4.0 but anyways those are your fuel reading.

at idle it prolly is like 10-12, when u gas it goes up obviously but look at it when you coast down a hill in gear and in neutral, the gear will be 0 until you put your foot down.
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Old 03-02-2013, 11:18 PM   #16
gselsidi
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Originally Posted by ruskisky View Post
25 is fine highway driving.

if you're always driving at 55mph without braking/accelerating and always in cruise, you can get 28.

i've done a few trips, where i would reset my mpg gauge, put cruise at 65-67, and get in 27-28 but this is slow ass driving.

as far as your myth on coasting into neutral and helping your car save gas, you are wrong. the ecu knows when you let go of the gas and if you are in gear it will stop delivering fuel, so keeping it in a higher gear (lower revs) on a downhill will "turn off" your fuel pump.

think about this, in order for the car to be in neutral... there has to be fuel being pumped but this is not the case when you coast down a hill in gear without gas pedal.. anyways your computer knows!! i am late to sleep

if you don't believe me, go into hidden obc, i believe its the 4.0 but anyways those are your fuel reading.

at idle it prolly is like 10-12, when u gas it goes up obviously but look at it when you coast down a hill in gear and in neutral, the gear will be 0 until you put your foot down.
yeah 65-67mph and you are getting 27mpg, im doing 55mph which saves about 20% gas consumption and I am lower than you. No neutral is not a myth because like I mentioned I have tested it before hundreds of times with the same route it always gives me better mpg by 2-3
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Old 03-02-2013, 11:20 PM   #17
gselsidi
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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.
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Old 03-03-2013, 12:19 AM   #18
tks
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Originally Posted by gselsidi View Post
yeah 65-67mph and you are getting 27mpg, im doing 55mph which saves about 20% gas consumption and I am lower than you. No neutral is not a myth because like I mentioned I have tested it before hundreds of times with the same route it always gives me better mpg by 2-3
The fuel pump IS SHUT OFF when the vehicle experiences a long (more than 2 seconds), high speed, closed throttle coast down. This does NOT happen in neutral.

The reason you're getting an extra 2-3 mpg is because you take a **** during the day.

Maybe check your tires, number one culprit if overlooked.
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Old 03-03-2013, 12:44 AM   #19
gselsidi
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Originally Posted by ruskisky View Post
The fuel pump IS SHUT OFF when the vehicle experiences a long (more than 2 seconds), high speed, closed throttle coast down. This does NOT happen in neutral.

The reason you're getting an extra 2-3 mpg is because you take a **** during the day.

Maybe check your tires, number one culprit if overlooked.
doesn't matter if it doesn't shut down, you have to step on the gas to keep your speed constant when you coast, thus negating fuel pump shut off. In neutral you can coast longer down the hill, so the benefit of the shut off doesn't matter.

Cool story about the ****, proves a lot.

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Old 03-03-2013, 01:08 AM   #20
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It could just be that your engine is not running as efficiently as it should. When did you do your o2s? How about tires pressure, tune ups? is there a ridiculous rice rocket wing mounted on your trunk causing drag? does the route you take provide a flat terrain with little or no elevation variation? Have you switched from the subway to the mcdonalds diet? if you want to diagnose your o2s, I'd recommend just replacing them every 100,000 miles. sure they could last longer or crap out sooner. either way, if you want your engine running efficient, just change them. If you intend on checking them, might as well switch it right then and there, especially with the post cat o2s. Once you're down and in there, you don't want to go back in man.

The o2s are cheap, if you know where to look. If you're the type to drink BMW kool aid, feel free to join the mindless zombies who are still doing so. If you're smart, you buy the o2s directly from bosch, like I did, searching for it by the part number. The only difference I can tell is on one packaging, it has bmws name slapped all over it with probably one spot with the name bosch. the other has bosch on a couple places in regular packaging. I don't see how a company who makes the o2s for a car company as an oem part could somehow fail at recreating that same part and resell it with just their name on it. as far as pricing, go oem, $100+ a piece, which I on my car with the euro tune, only the front 2 are being monitored anyways so I have post cat o2s just sitting there as fancy hole plugs. If you buy directly from bosch like me, I ended up paying a little under $250 for all 4.

Even with the Euro tune which I would have to assume consumes more gas, if I reset the obc mpg readings while rolling at highway speeds, approximately 75mph with no city driving, this bad boy can average around 24-25 mpg with your occasional WOT to pass those idiots who need to get off the fast lane. I also used to drive city only, with little or no highway at all and I averaged around 14MPG, and that's after a full tank. Of course, factor in the occasional WOT on those punks thinking they tough. I didn['t pay too much attention to MPG prior to euro tune except I swear when I did this one time, my car did average around 26-27 strictly highway miles.

A drawback of the euro tune is that with its increased throttle response, that right there helps eat away the fuel. I've monitored live driving data and noticed the throttle load at a much higher percentage than before. also, during red light stops while in gear, figures show my throttle load around 12-23% but while in neutral, throttle load shows to be around 6-8%
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