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Russian Bimmer
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299 Posts
Discussion Starter #1
Hello ,
i've e39 520I with vin wbadd11030bn63605

as i read , the fuel consumption should be between 9-12 L/100 km
but i found on my dashboard monitor that it says 20.2 L/100 km
earlier ive changed the spark plugs to original ones, the fuel filter, the air filter
what might causes that problem since 20L/100km it's way to much
 

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Jerome
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77 Posts
It depends on the kind of driving and how you drive. If it's all city driving then 20l/100km can be expected.


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Russian Bimmer
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299 Posts
Discussion Starter #4
1

It depends on the kind of driving and how you drive. If it's all city driving then 20l/100km can be expected.
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well yeah, it's all in the city, but in summer it was always somewhere in between 12-15 L/km
is the cold weather affects the mileage too ?
 

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Jerome
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77 Posts
Go on fuelly.com
You'll be able to compare with what others are getting.

Vacuum leaks cause increased consumption and are pretty common on those engines. Check all the rubber hoses for cracks, the one between the maf and intake is a common one that fails.


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Jerome
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77 Posts
Cold weather also makes it worse, the ecu runs the engine rich and at higher revs until up to temp


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Russian Bimmer
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299 Posts
Discussion Starter #7
Cold weather also makes it worse, the ecu runs the engine rich and at higher revs until up to temp


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thanks alot for your help :thumbup:
 

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Registered
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2,514 Posts
Any codes?
 

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Registered
2001 BMW E39 540i Automatic Sedan, 192 K miles
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1,586 Posts
Cleaning the MAF (mass airflow), the throttle plates, and the fuel injectors can improve your gas consumption (miles per gallon, or km per liter).
Use CRC or any carburetor cleaner, and let them dry.
Reset the adaptations after the clean-up.
 

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Russian Bimmer
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299 Posts
Discussion Starter #11
Cleaning the MAF (mass airflow), the throttle plates, and the fuel injectors can improve your gas consumption (miles per gallon, or km per liter).
Use CRC or any carburetor cleaner, and let them dry.
Reset the adaptations after the clean-up.
Looks like complicated process, will try to dig it up on YouTube, thanks though

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Under the lift arms
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12,957 Posts
what does your live data say,

what is the engine temp operation at

what is the down stream signal look like..

you can not just guess, and because your scan tool doesn't work doesn't mean there is no problems:

spark plugs, air filter, fuel filter... (basic #1)
 

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Lazy pre-cat O2 sensors can also add to fuel consumption.
 

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Russian Bimmer
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299 Posts
Discussion Starter #15 (Edited)
Well, i started cleaning the system
1-changed air filter
2-changed the fuel filter
3-changsd spark plugs
4-took massflow filter out to clean it with its special spray

After taking off the massflow, the view was as shown in the pictures it felt kinda oily or something , is that normal?

Going to check the rest of things as you all mentioned and keep you updated ))


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Lazy pre-cat O2 sensors can also add to fuel consumption.
That was the case with our last car & this is what I'm facing with our 530i...unknown how long ours have been in (not showing replacement in the BMW maint through 4/09 anyways, and hideous in-town mileage. I know many suggest just replacing the pre-cat sensors, but our mechanic suggests always replacing both sets at the same time. Being as they are likely as old as the pre-cat units, I went ahead and bought the Bosch full set.

Will update when they are replaced with results to try and help our OP here.
 

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Under the lift arms
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12,957 Posts
why would you throw o2's at the car if the O2 sensor is with in range..

The o2 sensors have a set amount of threshold negative and positive From zero.. If your with in that range.. there is no o2 code.. there is no problem..

I think this is poor diagnostic work... Again.. LIVE DATA

To put that in to prospective 250,000 miles on my O2's
 

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why would you throw o2's at the car if the O2 sensor is with in range..

The o2 sensors have a set amount of threshold negative and positive From zero.. If your with in that range.. there is no o2 code.. there is no problem..

I think this is poor diagnostic work... Again.. LIVE DATA

To put that in to prospective 250,000 miles on my O2's
250,000 miles on your original O2 sensors is admirable.

You can call it 'poor diagnostic work' if you wish. That said, tired sensors often will cause poor city mileage.

Example: Mech went though that with our former Passat (1.8 turbo). Went through all the normal checks and scans...vacuum leak test, etc. Nada. And the car passed CA Smog with flying colors last fall...the car only had 90k original miles. Normal HWY gas mileage, but poor city MPG. Anyways, we replaced the O2 sensors at my nudging with some new Bosch sensors, and boom, city gas mileage increased SUBSTANTIALLY.... went from 13.8 up to 18-20 mpg. NO change in driving habits, etc. Can't argue with results. BTW, I just looked a little while ago, and yep, these in our 530i appear to be the originals by part number and what I have of the vehicle history. YMMV. SInce i have this minty fresh Foxwell, what range should I be seeing? Even so, I still believe tired O2 sensors can cause exactly what I'm battling. I'd much rather spend the cash elsewhere if it wasn't necessary. lol
 

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Under the lift arms
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12,957 Posts
i have a v8, im not sure off the top of my head if the range is the same.. I know we have different MS versions

the proper way is to data map the responce of the O2's. they can be slow to respond but still be with in range... They can be close to out of range and still maintain the threshold

If your mechanic doesn't want to take the time to test the car when its cold.. test the car after its been warmed up... take it for a ride log the data and chart it..

your essentially throwing parts at it

the foxwell will log and capture data.. honestly ive never done it with the nt510 yet.. i just havent had the need to... but now that we have had this conversation.. and ive put my cards on the table.. Im sure karma is coming.. So ill go poke around and see what i can see
 

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i have a v8, im not sure off the top of my head if the range is the same.. I know we have different MS versions

the proper way is to data map the responce of the O2's. they can be slow to respond but still be with in range... They can be close to out of range and still maintain the threshold

If your mechanic doesn't want to take the time to test the car when its cold.. test the car after its been warmed up... take it for a ride log the data and chart it..

your essentially throwing parts at it

the foxwell will log and capture data.. honestly ive never done it with the nt510 yet.. i just havent had the need to... but now that we have had this conversation.. and ive put my cards on the table.. Im sure karma is coming.. So ill go poke around and see what i can see
Hey no pressure, brother! lol All ears when you do. As a former fleet wrench ( I left that in 2001), there is nothing I detest more than "parts changers"..what it appears that I'm doing. lol

See, I've only had the car for going on 3 months. My "throwing parts at it" is not so much shots in the dark AT ALL, but taking care of a few unknowns and establish a baseline of "these were replaced on X day, miles", because of the mystery of not knowing just how many miles ARE on them....coils OR plugs, let alone the O2 sensors which appear to be original.

We've no maintenance history on the car since 4/2009 except for the recent cooling system refresh, tires, alignment, all filters and oil changed right before we bought it. So, my reasons for doing the above are as such.

I'd rather pull the coils & plugs, just replace them with new and be done with it instead of waiting for one (coil specifically) to poop out on the HWY to anywhere, USA. And they WILL take a dump usually at the most inopportune moment.

Much respect for your opinions and standpoint....hopefully you can see mine, brudda. If not, we can still share the BMW brotherhood. :beerchug:
 
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