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Discussion Starter #1
Hi everyone,

Its been 3 month that my car been useing fuel like crazy.For a full tank ,if im lucky i get 170 MPG.:sad1: Before i use to get 260-280 MpG.

All I did is change the fuel filter about a year ago,and recently(5 month) changed the oil.What else i need to do to improve my fuel consumption.:confused2

BTW ,My car is 2000 with 37000 miles.
Any help would be great and thanks in advance.:1zhelp:
 

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Hi everyone,

Its been 3 month that my car been useing fuel like crazy.For a full tank ,if im lucky i get 170 MPG.:sad1: Before i use to get 260-280 MpG.

All I did is change the fuel filter about a year ago,and recently(5 month) changed the oil.What else i need to do to improve my fuel consumption.:confused2

BTW ,My car is 2000 with 37000 miles.
Any help would be great and thanks in advance.:1zhelp:
Geez, I wish I got 170 miles per gallon - if I were you I wouldn't complain!

I'd check to make sure you tightened all the connections on the filter correctly - unless you have a leaking connection there is no reason either should have any impact on fuel consumption.

d-
 

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170 MPG??? This is so great, what a nice economical car. Are you running on 1 cylinder? :) :) : )
 

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Are those the only changes that you've made? Is your driving style the same? Do you get any codes? Have you checked your spark plugs? MAFs?
 

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fuel consumption is based on a few things. it comes down to the air to fuel ratio. first and foremost, check the air filters. if they are clogged then replace them. Also have you been buying gas from a different supplier. Some gas stations will have regular dumped as super or premium. BMW need super or premium here in the States as regular in Europe and Asia is 93 octane. I buy my gas from Costco believe or not. It is a corporate owned and the attentants could care less if they are making extra cents on gas sales unlike a privately owned station. Octane boost only increase the octane by .1. If you have a station that sells racing fuel, buy about 4 to 5 gallons, do not fill the tank! Racing fuel is 110 octane and can cost 8.00 and up per gallon. If these do not help, then have the spark plugs check as they may not be firing efficently any longer. After that there are o2 sensors, and air leaks, but these generally set a check engine light. If the spark plugs are too far gone then they will set a check light as well. Hope this gives you some insight to your problem.
 

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You didn't say how many gallons you filled it with. I might be able to help if I knew.

There are 2 fuel sensors. If one fails or both stick, your gas gauge could be sending the wrong message.

My rule of thumb is: Fill up when the reserve light comes ON. You should be able to put at least 15.5 gallons in after the light just comes on.

(And, I guess you have checked for leaks. My fuel tank (they're plastic) leaked and was replaced a couple of months ago.)

You shouldn't have caused it by changing the fuel filter (the one under the driver's side?) or the oil.
 

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Discussion Starter #7
Are those the only changes that you've made? Is your driving style the same? Do you get any codes? Have you checked your spark plugs? MAFs?
Yes those the only things that I done (done at the dealer).driving style still the same.
I got SES code once in the past 3 month .It was p0441 It satyed on for 2 days then it went away ,and i never seen it again.

I never checked the spark plugs,and the MAFs seem ok no limp mode the car drive good.
 

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Limp home mode is only active if your check engine light is on. That P0441 is the evap system code, more than likely you filled the tank without turning off the engine or the cap wasn't tightened well. Or it could be that rain shorted wires on the undercarriage of the car that deal with the data line or ground/power feed to part of the evap system. There are many ways for air leaks or fuel leaks to happen. Have someone check the fuel trim on your car. They will need a modis or OBDii compliant scanner. It doesn't have to be from the dealer and it they don't have euro package on the scanner you can still check it through generic mode. LTFT and STFT should be around + or - 5 and no more, you are wanting 0. This will tell you your air fuel ratio is where it needs to be or not. Autozone in this area does check for codes with OBD vehicles for free, I don't know if they read the data stream though. If you were in my area, I would tell you to stop down and I would check it for you. I kindof play with cars on a daily basis so I have the equipment to test things.

Ladykats
 

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OKay, you want to technical, I have Shopkey5 with software up to 2007, criteria for this code is:

purge valve hold in closed position
Big System Leak
(e.g. missing filler cap )
faulty purge condition system leak ( 1mm )
Shut off valve hold in closed position

I can give you the condition and there values to set this code as well, but being that he stated that the code had gone away, and with some vehicle if it is a one time event, then the ecu will turn off the light after x amount of starts, but keep the code in memory. As I stated before, he filled the car with the engine running or it was a short caused by moisture. Or his light would still be on.
 
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