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Discussion Starter · #1 ·
Hey guys, I tried searching for this and nothing really matched what I have going on. Sometimes, when accelerating, the car starts vibrating hard. This is going on around 2K RPM, and it starts getting really bad around 3-4K RPM. I think it might be the engine mounts, mostly because I think they have never been replaced and the car vibrates a bit at stoplights and so on.

I had the P0174 code and a couple others, mostly dealing with misfires on low fuel so I changed the fuel filter and those seem to have gone, but I still have the P0174 code, so could that be the issue?
 

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You need to look at everything from fuel trims, to front axles to a bad fuel pump.

Suggest you read the first 2 links below in my signature.

Also I assume your 325xi is not an M56 SULEV??
 

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CCV and hoses, DISA and O-ring, intake boots, vacuum caps on the rear of the intake are all common problems as is the fuel pump. At 10 years old, I would put a fuel pump in the car.

Post Freeze Frame and warm idle and steady cruise Fuel Trim info.
 

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Discussion Starter · #6 ·
Post Freeze Frame and warm idle and steady cruise Fuel Trim info.
Sorry for the last response, long day with college classes. Anyway, I read all the info and took screenshots of it from my iPad:

Freeze Frame:


Warm Idle:


Cruise 1:


Cruise 2:


Nothing really looks too out of the ordinary. I also looked more into the vibrations and many are claiming that because it's an XI that the CV boots are torn and that's causing problems.
 

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Fuel Trims are too high. You have a Lean condition. I would have liked to see the cruise info at 50-65 MPH, mainly want to see where the fuel trims are at highway speeds.

LTFT should be in the 0% to + 2.5% range, you are over 10% so this is why you are seeing the P0171/P0174 codes.

You have a fuel pump or MAF issue would be my first guess. But I would like to see more data at highway speed.

You may also have CV joint issues as well as Lean problem, so is the problem misfiring and/or CV joints.

Also the engine temp may be suspect, should be around 205F but not sure how long you had been driving when the Freeze Frame was captured. Engine needs to hold 96C/205F on the highway when the outside temps are below 70F.
 

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Discussion Starter · #8 ·
I could get that info tomorrow, just 50-65? Also, if it's a MAF issue, would cleaning it be enough or should I look into replacing it?
 

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Cleaning a MAF is mostly an urban myth in my opinion, but you will have others that swear this is the way to resolve MAF issues.

The MAF is usually the last thing I touch on any car, they are stupid expensive and actually last pretty long. All my cars have original MAF that have never been cleaned up to 110k mile and from as far back as 1996.

I have seen more cheap/counterfeit MAF's installed and cause more headaches than anything else.
 

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Discussion Starter · #10 ·
I got some cruise numbers, and wow, the fuel trims are high.





I'll look into a new a new fuel pump, would it be worth it to go OEM or is something else fine?
 

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Here is the deal, Fuel Trims high at highway cruise are typically MAF related, but could be fuel pump as well.

You have a few choices. Test for fuel pressure and volume or just replace the fuel pump first as it is cheaper than the MAF and when the pump fails it will leave you stranded.

2nd link in my signature. www.bmaparts.com Siemens/VDO pump/sending unit with discount code SPECE30 is about $125 on your doorstep with standard shipping, which is FAST.

MAF, you MUST purchase a MAF from a reliable source, it will probably be over $200. DO NOT BUY from the local parts store or ebay. There are MANY Asian counterfeit MAF's on the market and this may be your problem??

You can use these pricing tools to find the best price on a quality MAF -

http://www.bmwpnpc.com/

http://www.furiousmethod.com/

OEMbimmerparts.com often has very good prices and quality products.

Good luck.
 

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Discussion Starter · #12 ·
Thanks for the fuel pump info, looks like I'll be changing it next. It really seems to die out a lot and with my car having over 133k and probably the same fuel pump, I guess it's time for a change.

Also, I believe the MAF is OEM, never changed. The previous owner always took it in for service at the dealership so doubt the MAF is a counterfeit.
 
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