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Discussion Starter · #1 ·
Just got back from a 400 mile round trip with my E46. First problem is my gas mileage. I average 22 MPG, but it is mostly city so I wasn't concerned. Thought I would see a good increase on this trip, but it didn't happen. I averaged 23.

My SES light came on half way through. Autozone read the code P0174. Plan to clean the MAF tomorrow.

Also noticed it shaking while braking. I will try to rebed them tomorrow too. I should have some time this week to take the wheels off and inspect the brakes.

The car is still running/idling great.
 

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There is some work that needs to be done there. I average 30mpgs with my 330ci fully loaded with people or stuff. Did you actually measure your milage at the pump, distance traveled divided by how many gallons you put in? Or is that what the computer told you? Also did you reset the trip computer and such before you left or does your average include all of the city driving you have been doing prior to the trip?

Vanos is good for a few mpgs, reseting the adaptation values is good for a few more. I used to only get 28mpgs best, now since I replaced the vanos seals and reset the adaptations I top out at 32mpgs.

Cleaning the MAF should help as well. Good luck!
 

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Discussion Starter · #4 ·
I just used the computers average, didn't think to reset it.
 

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Oops, then you probably got better than you think. Reset it next time, I have found that my computer is about 1 to 1.5 mpgs optimistic. So usually its not quite as good at it says, but close.
 

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ohhh my! Of course you didn't I am pretty much sure you averaged somewhere close 30s!!!
+1, I use the OBC number as a long term fuel economy average. When going on a road trip I do it the old fashion way, resetting the odometer trip function and calculating mileage based off of how many gallons it takes to fill up. On long trips I come close to 30 mpg, with a LOADED car.
 

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Discussion Starter · #8 ·
I planned on doing that too Tock. The SES scared me. I pulled into the first Shell station ASAP to give a visual inspection(I only use V-Power). Threw $20 in it since I had my hood up checking all fluids, belts, and hoses. Luckily the Autozone was less than a mile. That and the bimmerapp made me feel comfortable enough to finish my trip.
 

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If you want accurate MPG via your trip computer than you need to reset it prior to your trip. If not your MPG is being averaged in with your MPG you have been getting since your last reset. Ultimately this entire thread is pointless in that aspect.

Your shaking while braking could be your brakes OR perhaps your front control arms.
 

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The shaking while braking could be from bad FCAB's or build-up in the rotor from the brakes not bedding correctly. Warped rotors are not as common as people think. It is usually transference of pad material to the rotor. I am assuming that you had the rotors turned before you installed new pads, the last time you did it. If not, get them turned, of course. If there has been some build up of pad material on the rotor, you may need to get them turned again as well.
 

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Discussion Starter · #12 ·
Cleaned the MAF and cleared the code. Drove for @ 15 miles and it didn't re-appear. Hope that was it. Changing the fuel filter and plugs Thursday. The shaking is very minimal when I never get over 50 mph.

Hard to get a good mpg read around here when it is always stop and go.
 

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Discussion Starter · #14 ·
Still haven't looked at the tires, the shaking is very minimal. Got up early this morning and changed the fuel filter and plugs. The filter on there was Kaiser, so I am guessing it had been changed before.

Here are the plugs that were in it, and the NGK's I put in.

[/URL] Uploaded with ImageShack.us[/IMG]

On the up side, cleaning the MAF seems to have taken care of the CEL.
 

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I pulled into the first Shell station ASAP to give a visual inspection(I only use V-Power).
Good choice, I only use V-Power as well. Another to thing to try in addition to the numerous other suggestions in this thread is Liqui-Moly. Run a bottle of Jectron fuel injector cleaner through and then a few weeks later run a bottle of their Ventil-Sauber valve cleaner. I've used both on many of my previous cars and I've always been happy with the results. I'm running a bottle of Jectron through with my current tank of gas actually.
 

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Discussion Starter · #17 ·
How did you get your car high enough to access the fuel filter?
Mine is so far under that I couldn't reach it with ramps.
Put my floor jack under the center jacking point, got it up and put jack stands under the front jacking points.
 

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Discussion Starter · #18 ·
Good choice, I only use V-Power as well. Another to thing to try in addition to the numerous other suggestions in this thread is Liqui-Moly. Run a bottle of Jectron fuel injector cleaner through and then a few weeks later run a bottle of their Ventil-Sauber valve cleaner. I've used both on many of my previous cars and I've always been happy with the results. I'm running a bottle of Jectron through with my current tank of gas actually.
I ran Techron though it when the fuel gauge was not going all the way to full. I will look into those too.
 
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