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Old 02-26-2020, 12:00 PM   #1
E46Legend916
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Need serious help

Hello, about a year ago I purchased a 06 325ci in amazing condition. Over the last year it has been nothing but reliable and a **** ton of fun to just cruise in, road trips and long distance drives are never uncomfortable, and the response of the car will always leave you wowed at the end of the day. However I did not come here to boast about how much I love my car, I came here because I have been having this weird "low power/TERRIBLE GAS MILEAGE" problem for the better part of 5 months. 1st let me add the small modifications and service that I have done to the car maybe it's something that I've done that I just keep over looking. ( IN NO WAY SHAPE OR FORM A MECHANIC, STILL VERY MUCH LEARNING ABOUT CARS AS A WHOLE).

1. I have the muffler and the first resonator gone and replaced with 3 inch piping.
2. Wheels, although I'm sure that's not a factor.
3. I replace the bank 1 sensor 1 02 sensor about 2 months ago.
4. Oil change literally 5 days ago, at 196,000
5. Replaced spark plugs at about 174,000


Now here's the problem, and I already know i may get hate for this but, buying the car was a mistake, I was very very young, honestly got finessed but I won't say how much I paid for it. Got it from a 3rd party dealership so already extremely sketchy. Like I said none of this matter but maybe I'm overlooking a major issue I've just been blind to.
To describe the problem is like pulling teeth, especially not being a mechanic. A couple month ago the check engine came on and read the 02 sensor, this gas issue was a major issue back then so in hopes that the new part would fix this, I immediately changed the sensor. Last month the car was idling TERRIBLY, on cold starts. It would shake so bad you would think the engine was going to just blow. The check engine light that came on then, displayed that it was a MAF. Since I didn't have the money, I just bought cleaner and it fixed the bad idling problem. Believe me I will be replacing it soon but the thing is, after the 02 sensor I made it a pact to myself to not spend anymore money on the car unless I nail the issue and fix it, that's why I haven't bought a new MAF. Like I said before describing the gas issue can get really confusing, just know that I'm at the gas station once a day. $10 dollars a day. The computer says I'm getting 20mpg but that couldn't be father from the truth. Just like it hard to describe, it's also hard as **** to show. Thankfully I got it on video one time. I know this post is all over the place but the main question is , WHY THE **** IS THIS HAPPENING, WHY AM I GETTING SUCH LOW MPG?!!!! PLEASE HELP I don't want to take it to a mechanic so they can screw me.
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Old 02-26-2020, 12:53 PM   #2
BobC63
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Sorry to hear of your problems.

First question: How do you know it's the MAF? Do you have a CEL code reader? If you do, what codes does it show?

Second: Have you ever done a smoke test to your car? It's a great way to locate vacuum leaks... which MAY be contributing to your rough idle / poor mileage issue.

Third (more a comment than a question): Be sure that when you do replace parts on your vehicle, that you use OEM or equivalent. I know it can be tempting to save money using box store brands - but these cars seem to be very sensitive to that. Pretty much any part that you want / need to replace you can just ask on this Forum... "What's a good brand of _______ to get?" (insert part name) and you will get really good advice that, in the long run, will SAVE you $$$ from not having to buy the same part twice (because the first one was a sh*tty brand that was $20 cheaper than the OEM part)....
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Old 02-26-2020, 01:11 PM   #3
CylonRed
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The computer says I'm getting 20mpg but that couldn't be father from the truth.
Calculate the MPG by hand - about the only way to need gas every day is to drive 300+ miles/day or a gas leak.

Go to the pinned thread at the top of the forum and read about ODBFusion and a compatible Bluetooth ODB reader to get more information and potentially more codes. I would agree with the above poster that a vacuum leak is possible. You can read about those in the same pinned thread.

Last edited by CylonRed; 02-26-2020 at 01:12 PM.
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Old 02-26-2020, 01:15 PM   #4
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Don't replace the MAF yet.

DO replace the other pre- cat oxygen sensor. Buy the same brand you used the first time.

DO download PASoft 1.4 and get a cable for it (search this board to find out how)

and also get a decent 3rd party app for your phone/tablet and a blootooth adaptor for that.

DO make sure you have an E46 and not an E90!

hope this helps
t
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Old 02-26-2020, 01:47 PM   #5
BobC63
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Originally Posted by CylonRed View Post
Calculate the MPG by hand - about the only way to need gas every day is to drive 300+ miles/day or a gas leak.

Go to the pinned thread at the top of the forum and read about ODBFusion and a compatible Bluetooth ODB reader to get more information and potentially more codes. I would agree with the above poster that a vacuum leak is possible. You can read about those in the same pinned thread.

Actually, he posted "...I'm at the gas station once a day. $10 dollars a day." He's not using a tank of gas a day.

And $10 worth of gas could be as little as 2.5 gallons, depending on where he is located and if he is using regular or premium gas. California is still close to $4 / gallon for premium...

And he could be burning through $10 worth of gas in as few as 50 miles and be totally in the normal range for mpg... especially if he does any "city" driving.
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Old 02-26-2020, 04:05 PM   #6
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Originally Posted by BobC63 View Post
Actually, he posted "...I'm at the gas station once a day. $10 dollars a day." He's not using a tank of gas a day.

And $10 worth of gas could be as little as 2.5 gallons, depending on where he is located and if he is using regular or premium gas. California is still close to $4 / gallon for premium...

And he could be burning through $10 worth of gas in as few as 50 miles and be totally in the normal range for mpg... especially if he does any "city" driving.
I can't think of any reason to add $10 of gas in the tank ad-hoc. He still has NO clue as to the actual MPG (he might find the computer is a bit closre than he thinks) and has nothing in the post that would help explain the MPG he is actually getting.

He would be FAR better off not adding gas till the prices go down during the week than adding $10/day.

Too much has to be extrapolated because he does not have the needed facts to determine anything.
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Old 02-26-2020, 04:34 PM   #7
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Agreed... the OP really hasn't given us much information to work with. Curious that he's putting in $10 in gas / day - instead of just filling it up and refilling when down near E...

Hopefully, he responds with more details.
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Old 02-27-2020, 09:09 AM   #8
E46Legend916
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Quote:
Originally Posted by BobC63 View Post
Agreed... the OP really hasn't given us much information to work with. Curious that he's putting in $10 in gas / day - instead of just filling it up and refilling when down near E...



Hopefully, he responds with more details.


I donít put 10 dollars in the tank a day just because I feel thatís needed. Iím on E every single day. Iíll put about 2.5 gallons in, just to end up on E at the end of the day. I only go about 30 miles after filling up, and I donít put over 10 on because it almost feels like the gas is evaporating into thin air. Thatís how fast I run out of gas.


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Old 02-27-2020, 10:54 AM   #9
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Originally Posted by E46Legend916 View Post
I donít put 10 dollars in the tank a day just because I feel thatís needed. Iím on E every single day. Iíll put about 2.5 gallons in, just to end up on E at the end of the day. I only go about 30 miles after filling up, and I donít put over 10 on because it almost feels like the gas is evaporating into thin air. Thatís how fast I run out of gas.
What you are saying does not make any sense. Fuel will not evaporate anywhere near that aggressive of a rate and if you had a bad fuel leak, it would be pretty obvious.

Need a baseline to understand what is going on:

1. Fill up the car fully.
2. Reset the trip meter.
3. Drive (minimum 1/4 tank consumed).
4. Refill fully.
5. Calculate: Miles Driven / Fuel Added (In Step 4)
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Old 02-27-2020, 11:08 AM   #10
BobC63
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OK, thanks for the clarification.

Now, I have to tell you that what you are doing - running the vehicle with the gas tank almost empty / empty constantly - is a very BAD thing for your car.

It's bad for the fuel delivery system (fuel pump, fuel filter, etc.) and it's bad for your engine.

Why? Because running with so little gas (and so much airspace) in your tank will expose your fuel pump to air (especially when turning or stopping / accelerating) and can possibly cause short - term cavitation (intervals of air getting into the fuel line). Your fuel pump also relies on gasoline as a cooling agent; being that low all the time is causing your pump to run warmer than normal and WILL shorten its life. Any cavitation getting in the fuel line and up to your fuel filter is going to erode the filter media and possibly cause some tiny particles to migrate into the fuel and then forward into your engine. Also, since your vehicle is 14 years old and has fairly high mileage you will have a bit of 'gunk' that has settled and accumulated over the years in your gas tank. Not usually a problem - but by keeping the fuel level so low ALL THE TIME, you are allowing fuel to constantly slosh around there and again almost definitely carrying particulates forward to the fuel pump and filter... if not all the way to the combustion chamber.



So first thing you need to do (IMO) -

Get yourself a can of Seafoam fuel system cleaner and put it into your tank. Then fill up completely and run until down to about a quarter tank before you refill the tank. Make sure you are using at least 'mid-grade' gasoline, if not premium.

I know you think you are somehow helping the situation, maybe creating the illusion that your gas is lasting longer, by refueling a small amount daily... but I can 100% guarantee you that you are not make the situation any better - and very VERY likely you are making it worse.

Last edited by BobC63; 02-27-2020 at 11:10 AM.
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Old 02-27-2020, 11:25 AM   #11
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Second thing you need to do is give us the information we initially asked for so we can help.

1) Have you had the vehicle scanned for error codes? Do you have your own scanner or did someone else do it for you? What codes did you get?

2) Have you ever done a 'smoke test' on your vehicle? Best way to check for vacuum leaks which MAY be causing your symptoms.

3) When's the last time you changed your:

- Air filter
- Fuel filter

4) Do you have any mods on the engine / airbox etc. or is everything stock?

Running normally, your car should be getting around 20 mpg (assuming you are not racing / drifting it or driving in constant heavy traffic). Right now, it sounds like you are getting at most 14 - 15 mpg. There could be a ton of reasons for that. It could be one major issue, or a bunch of smaller issues combined. Same for the rough running and rough idle.

The members on this Forum can definitely help you - but we need more information.
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Old 02-27-2020, 11:38 AM   #12
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Add the specific fault codes (in Pxxxx format) you currently have to your original post #1 above.
Look up their descriptions on a website like one of these.
https://www.obd-codes.com/
https://www.autocodes.com/

Don't have an app to read fault codes? See this thread.
https://forum.e46fanatics.com/showthread.php?t=1240733
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Old 02-28-2020, 08:07 AM   #13
CylonRed
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If the fuel gague says it is empty and you only put in $10 (2.5 gal) then the tank is NOT empty. You would be adding 15+ gallons if it was empty.
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Old 02-28-2020, 10:23 AM   #14
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Originally Posted by E46Legend916 View Post
I donít put 10 dollars in the tank a day just because I feel thatís needed. Iím on E every single day. Iíll put about 2.5 gallons in, just to end up on E at the end of the day. I only go about 30 miles after filling up, and I donít put over 10 on because it almost feels like the gas is evaporating into thin air. Thatís how fast I run out of gas.


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OP not srs about fix car.

t
moving on
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Old 02-28-2020, 11:29 AM   #15
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OP not srs about fix car.

t
moving on
yeah, OP super weird

Last edited by Kneedspeed; 02-28-2020 at 11:29 AM.
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Old 02-28-2020, 12:18 PM   #16
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Originally Posted by TobyB View Post
OP not srs about fix car.

t
moving on
But, OP does need some serious help.

Anyway, Toby I like your recent quotes after your signout "t". They are witty but true.
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Old 02-29-2020, 09:41 AM   #17
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I donít know why Iím coming off as not serious lol. Thereís only a few things that I can describe as the issue. I donít know the terminology like you guys do, all Iím saying is that my fuel economy is terrible, yes I did get a MAF code BUT I DONT KNOW THE CODE IN SPECIFIC! I donít know how much info you guys want and why Iím getting grilled in all these replies for not being ďseriousĒ


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Old 02-29-2020, 10:09 AM   #18
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Quote:
Originally Posted by E46Legend916 View Post
I donít know why Iím coming off as not serious lol. Thereís only a few things that I can describe as the issue. I donít know the terminology like you guys do, all Iím saying is that my fuel economy is terrible, yes I did get a MAF code BUT I DONT KNOW THE CODE IN SPECIFIC! I donít know how much info you guys want and why Iím getting grilled in all these replies for not being ďseriousĒ
Probably because you havenít replied to most of the advice. Without much specific information, no one can help you.

If it was me I would get a wireless OBD adapter and the OBD Fusion app set up on my smart phone or tablet and collect some data and post it in this thread. See the link in my post (#12) above for how to do that. First thing would be run a Diagnostic Report at hot idle as that provides a good snapshot of your engine parameters, trouble codes, smog test monitor status, etc.

Terrible gas mileage can be caused by a fuel leak, driving style, or running rich.
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Old 03-02-2020, 10:08 AM   #19
BobC63
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Quote:
Originally Posted by E46Legend916 View Post
I donít know why Iím coming off as not serious lol. Thereís only a few things that I can describe as the issue. I donít know the terminology like you guys do, all Iím saying is that my fuel economy is terrible, yes I did get a MAF code BUT I DONT KNOW THE CODE IN SPECIFIC! I donít know how much info you guys want and why Iím getting grilled in all these replies for not being ďseriousĒ


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-------------------------------------------------------------------------------------
Second thing you need to do is give us the information we initially asked for so we can help.

1) Have you had the vehicle scanned for error codes? Do you have your own scanner or did someone else do it for you? What codes did you get?

2) Have you ever done a 'smoke test' on your vehicle? Best way to check for vacuum leaks which MAY be causing your symptoms.

3) When's the last time you changed your:

- Air filter
- Fuel filter

4) Do you have any mods on the engine / airbox etc. or is everything stock?

Running normally, your car should be getting around 20 mpg (assuming you are not racing / drifting it or driving in constant heavy traffic). Right now, it sounds like you are getting at most 14 - 15 mpg. There could be a ton of reasons for that. It could be one major issue, or a bunch of smaller issues combined. Same for the rough running and rough idle.

The members on this Forum can definitely help you - but we need more information.
--------------------------------------------------------------------------------------

Still waiting for answers.
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