04-05-2017, 07:43 PM | #1 |
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MPG Dropping... and Dropping and... DROPPING
Hi everyone. I'm sure there are other threads about this, but I wanted to explain my car's symptoms exactly.
I have a 2010 X5M with 69,XXX miles on it, it has always been under warranty from Factory to CPO to Bumper to Bumper Warranty covered all the way thru 2020. Good news... When I got the car last July, I was averaging around 12-14 MPG overall, over winter I noticed it dropping to around 10-11MPG and most recently, I am averaging 9MPG or even less... Same kind of driving, no different routes or trips, etc... Car runs fine, no weird idle, no CEL, although some days it smells like the car is running rich, the exhaust smells sweet, etc. But not every day. Plugs were replaced under warranty at 53k miles on cylinders 5,6 & 8 and the injectors were all replaced on bank 2, according to the service history paperwork. What I don't want to do is just start throwing money at everything until I find the problem. Some things people have told me: 1. Walnut Blast? Carbon buildup cleaning? 2. Replace air filters with K&N? Not sure when they were replaced last. 3. Injectors 4. Spark plugs Anyone have any suggestions? Feel free to chime in... Thanks in advance, Chris
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04-05-2017, 08:15 PM | #2 |
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1) Walnut blasting is much harder to access on the reversed design of our V8 vs an I6. I've heard you might even need to lift the engine. I've seen pics though, and it seems gravity helps keep oil residue off the valves
2) You could just because they'll help a bit for better airflow. The S63 doesn't have a MAF, so don't worry about over oiling issues others mention with using K&N. 3) Them replacing only one bank is just being lazy and cheap. I'm going to assume it's injectors. Is the back of the truck peppered with little black dots are a HARD drive? If so, that's unburnt fuel due to leaking injectors. Best case scenario is bad mileage, worst case scenario is the engine hydrolocks when they leak over night. A cold start one morning and mine finally gave up...ran super lumpy, plumming smoke, I shut off right away. 4) Depending on how you drive, mods, etc they'll last about 50-100k. Last edited by m5james; 04-05-2017 at 08:21 PM.. |
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04-06-2017, 08:08 AM | #3 |
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04-06-2017, 12:13 PM | #5 | |
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04-06-2017, 12:23 PM | #6 | |
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My injectors were leaking for I'm guessing a month or so because I kept getting the peppering I mentioned above. Their final demise was going 170mph late one night when they finally failed. Thankfully I had an OBDII reader in my car and was able to reset the codes once it went into limp mode, still drove it home with no issues. The next morning was a completely different story as no amount of code clearing would allow it to run right and that's when I knew they were done. Long story short but I had to pay outta pocket for my injectors but eventually was reimbursed. I was getting a reduced power warning for almost 6 months, no CEL was kicked, but sometimes I'd get a pending code for boost pressure sensors which ended up all getting resolved from a vacuum leak. Point being is their sometimes dummy mechanics and SA's won't touch it unless a dummy light is on, which even then doesn't tell the whole story. I wish I had a CPO though :-) |
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04-07-2017, 09:31 AM | #7 |
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The thing about the limp home mode is, that it is setting a code. Though it will not always set a check engine light, there is a code there when you hook up with Reingold. At least that is the experience I have had with my current limp home issue, coming from boost sensor 2 I believe, could function differently for folks elsewhere, but I doubt if you hook up with an actually BMW OEM scan tool, it will not see something in the historic.
Still, why waste your own time when your under warranty. Warranties need to be utilized the way they were intended. I deal with dealer vendors all the time, once you put a bit or pressure, they usually cave and do what they are supposed to do. Although I do have the weight of a few hundred pieces of equipment behind me, the same applies to just one person. Worst case scenario, call up BMW NA, get them involved. Something is most obviously wrong with this truck, and needs to be addressed with a dealer warranty repair.
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04-07-2017, 01:25 PM | #8 | |||
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I know how to use a warranty, BMW NA won't do anything on a 2010 with nearly 70k miles that has an aftermarket warranty... but I appreciate the thought...
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04-13-2017, 09:29 AM | #9 |
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Oh, I am sorry to hear that. Aftermarket warranties are mostly, so bad, they are not worth using the paper they are printed on to clean your rectum after defecating.
Are these high pressure fuel injectors in the engine oil at all? Could there be a fuel leak somewhere?
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2005 Jeep Grand Cherokee 5.7L V8-Her stock DD 1995 Ford Thunderbird 4.6 V8 LX - A bunch of mods BMW guys don't care about 1995 BMW 540i6 - H&R Lowering Springs, Bilstein's, Racing Dynamics Bars, Catback, Short shifter |
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