Bmw 545i fuel consumption problem
10-18-2012 | 07:17 AM
#1
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Joined: Oct 2007
Posts: 225
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From: Roselle IL
My Ride: 2008 BMW 550i M Sport
Bmw 545i fuel consumption problem
Welcome forum members! I need help as stated in title. I have lost almost 5 MPG on my 545. I went to the dealer hoping to figure problem out but looks like they do not have a clue what is going on. Lets put aside driving habits I have a car for five years, so no changes in that. I made my calculations of mpg and looks like onboard comp is right. I get 15 mpg no matter what. I used to get 20. Car is at 84k miles. My engine was replaced at 54k so 30k miles ago. After replacement I was getting 19 to 20 mpg. I know this is a v8 but my friends x5 does 18,4 using same route so something is up. No check engine lights no faults whatsoever. Any ideas? Oh about a year and a half ago I've had mechatronics replaced. I think that is when it has started, but not sure. It feels like when you let off gas pedal car slows down harder than before but again not sure. I am running out of options here. Looks like that even though I have noticed 25% drop in mpg everything is fine according to the dealer cause there are no faults and no check engine light etc. please help!
10-18-2012 | 08:07 AM
#2
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Joined: May 2012
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From: Florence, SC
well first thing i'd do is see if car is running rich, few ways is the exhaust smell or alot of black smoke when accel., next check plugs and see color that will also let you know how it's running. now if your not running rich fuel milage is being lost by somthing else, like the computer always thinking car is cold (new thermostat should fix that) but again would be runnign rich but maybe not enough to have other two issues i mentioned first.
10-18-2012 | 08:52 AM
#3
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From: NYC
Just a thought, but has Illinois recently changed any fuel-formulation regulations (or been made subject to new Federal regulations) with respect to ethanol content? Do you buy gas at the same place as your friend?
I don't notice a 5mpg swing, more like 2-3 mpg swing when running alternate fuel formulations, but it could be something along those lines, which wouldn't trigger any warning lights (at least until the ethanol wrecks our engines entirely).
I don't notice a 5mpg swing, more like 2-3 mpg swing when running alternate fuel formulations, but it could be something along those lines, which wouldn't trigger any warning lights (at least until the ethanol wrecks our engines entirely).
10-18-2012 | 03:43 PM
#4
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Joined: Oct 2007
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From: Roselle IL
My Ride: 2008 BMW 550i M Sport
Dealer should check first if the car is running rich, instead I received solution that does not apply to my case. If I were driving this car for a month that would do it this time though changing driving habits after five years is not going to work. As for smoke I have not noticed anything. No smoke coming from muffler whatsoever...
10-31-2012 | 04:22 PM
#5
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Joined: Oct 2007
Posts: 225
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From: Roselle IL
My Ride: 2008 BMW 550i M Sport
Ok. so it took a while but i have some new information on my high consumption issue. What has been done is this. complete fuel system cleanup removing of carbon buildup from intake manifold, throttle body etc, compression test, and replacing two ignition coils because of random misfires. Car is running smoothly it feels as it has regained some of power, however I have driven it for 105 miles exactly and i have put 7.1 gallons of fuel!!!!!!that is 14.79 average WTF??? I am seriously starting to have enough. This car cost me more than supposed to every week at the pump. It had mechatronics replaced by the dealer a while back> comparing it to my friends x5 it feels as if it had a little more engine braking effect when releasing accelerator pedal, or i am making this just up... i am running out of options. Any help would be really appreciated...
10-31-2012 | 06:51 PM
#6
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From: New York
Did they disconnect the battery? you need to fill up the tank get on the highway and see what you get, all the computer resetting is making the computer start to relearn over again, could that be part of it??
10-31-2012 | 07:46 PM
#7
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From: Encino, CA
My Ride: 04 545i - Titanium Silver/Black, Sport pkg, Comfort Seats w/ Lumbar, Premium Sound, power rear sunshade, Adaptive Xenon Headlights, Steptronic, Park Distance Control, Fold down rear seats w/ski bag, Aux jack, 6-disk changer, puddle lamps...
Engine: Custom Remus cat-back exhaust w/chrome square tips, K&N Air Filter, Charcoal Filter Removed, Sprint Booster :-), 50/50 mix of 91+100 Octane, EuroRev ECU Remap (coming soon lol), Dinan High-Flow Throttle Body (coming soon...maybe lol)
Interior: Portable Sirius Stilletto 100 w/car kit, Garmin Nuvi 680 mounted below rear-view mirror, LCI-style I-drive knob, Dark Poplar Center Dashboard Trim.
Exterior: E60 forum clings, 5% rear tint, ACS roof spoiler (painted black for distinct look against limo tint), ACS trunk spoiler, ACS add-on front spoiler and rear apron (awaiting installation), "18 Black Staggered BeBeS Style OER (emergency replacement for cracked sport 124 rims), black kidney grill, white accessory lighting (including license and trunk lamps), Angel-eye upgrade, AIB xenon-matched fog lamps, AIB V3's on order, red rear reflectors
You state your mechatronics unit was replaced, and the problems possibly started around that time. Sounds like your transmission may be holding gears longer between shifts, leading to higher engine rpms (and increased consumption). I say this because of your description of "engine braking effect". Exhaust restrictions could also cause ncreased consumption. I'm going to assume you run her in "D", and not "DS" for these checks? Note your engine rpm at a steady 15, 30, 45, 60, and whatever your normal top cruising speed is. We can compare that way.
11-01-2012 | 06:35 AM
#8
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Joined: Oct 2007
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From: Roselle IL
My Ride: 2008 BMW 550i M Sport
Thank you for all replies! I think i need to exclude mechtronics as drop in mpgs did not occur suddenly. It was slow process i would say about a year ago when this started than at 17.5 mpg i switched cars with my wife and now it is at 14.8 it was constantly dropping slowly untill the point it is in now. Computer calculations does not have anything to do with it. I filled it up drove exactly 105 miles and filled up again. After that 105 miles distance travelled i have put in 7.2 gallons of premium f....ing fuel. I have this car for over 5 years now and i can not afford to sell it and buy a new one as i am moving to colorado next year and i will be buying a property there, so i want my credit history untouched till then. Car is paid off a while ago. It cost me every week at the pump...
Last edited by rafichicago; 11-01-2012 at 06:49 AM.
11-21-2012 | 07:54 AM
#9
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Joined: Mar 2011
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From: Toronto
My Ride: 545i
I am starting to have the same issue, my fuel consumption is dropping like crazy. When I bought the car, it started off really well at 12 Liters per 100kms (19.6012 MPG), now I am averaging 15 liters per 100kms.(15.681 MPG).
I will perform some tests and see what happens.
Sigh
I will perform some tests and see what happens.
Sigh
11-21-2012 | 06:58 PM
#10
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Joined: Oct 2011
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From: Wpg, Canada
My Ride: 545i
I am starting to have the same issue, my fuel consumption is dropping like crazy. When I bought the car, it started off really well at 12 Liters per 100kms (19.6012 MPG), now I am averaging 15 liters per 100kms.(15.681 MPG).
I will perform some tests and see what happens.
Sigh
I will perform some tests and see what happens.
Sigh