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BMW Starting Problems


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AndreiW
New User

Jun 26, 2020, 7:39 AM

Post #1 of 5 (170 views)
BMW Starting Problems Sign In

Hello all! First post here but I am at a complete loss of what to do and so is my mechanic.
Car is a 2003 BMW 330xi with just shy of 200K miles on it. Bought it used a few months back (nearly a year ago now).
A few days ago I unhooked and took apart my cars' main air filter and the casing for it. So that also means unhooking the electrical cord that plugged into the top of the filter case. Anyway, I took it apart to look for a leak that is going on and thought was ATF fluid so I took the filter out to see if I could see where the fluid was coming from better.
Put the car back together after I couldn't find it and since then....the car won't stay started. I can turn the key, it'll start but then within a second or two (very short time) it'll die. I can do this time and again and it does the same thing. I turn the key....car starts but then dies right away. There is now an electrical-type humming noise that lingers for a few seconds after the engine stops that I didn't notice before.
So I called my mechanic and he said it sounded like the immobilizer was tripped and wouldn't let me start it. So I have worked on troubleshooting that. I have replaced the key fob battery, I have unhooked the negative wire on the batter for a while, I have pulled fuses, I have locked and unlocked the car numerous times all to no avail. The car keeps doing the same thing.
So now I am wondering what to do and any help would be appreciated. The car was running just fine before I took the air filter out so not sure what is going on.......
Thanks!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 26, 2020, 8:19 AM

Post #2 of 5 (166 views)
Re: BMW Starting Problems Sign In

If you truly have an immobilizer issue, which I doubt, there will be a warning light flashing or message somewhere indicating this.

I'm more leaning toward you damaging or leaving a plug off for the MAF.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Jun 26, 2020, 8:20 AM)


tractorboy
User
tractorboy profile image

Jul 11, 2020, 7:00 PM

Post #3 of 5 (94 views)
Re: BMW Starting Problems Sign In

the hum could be the fuel pump.....are you getting a CEL ? CHECK ENGINE LIGHT? you might also have a gigantic air leak after the MAF . i would disassemble and reassemble, could be too as stated that the MAF is unplugged and you have not driven long enough to throw a code. have the car computer scanned for pending codes.


AndreiW
New User

Jul 13, 2020, 2:45 PM

Post #4 of 5 (63 views)
Re: BMW Starting Problems Sign In

Thanks, everyone for the responses! I greatly appreciate it!
I wanted to let you all know what I've done since first posting this.....
I ended up buying a new MAF sensor piece (the part that connects to the airflow container itself for like 50 bucks at a junkyard). I plugged in the wire and the same thing...the car died shortly after starting it. However, I have since unplugged it completely and the car runs fine now. Maybe even better than before if I am not mistaken as it seems to be shifting better.
I have not driven it far with this unplugged (at most like 30 miles) but interesting that it works without it plugged in. Tells me that the cord may be out of line a bit or loose....haven't looked yet
Thanks again!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 13, 2020, 3:27 PM

Post #5 of 5 (60 views)
Re: BMW Starting Problems Sign In

You shouldn't continue to drive it that way. The computer defaults to a "limp mode" and plugs in a default fuel mixture when it doesn't get a MAF signal. The computer no longer controls and adapts fuel mixture. If you live in a state with emissions testing, it will never pass. You need to have a professional diagnose it properly as it probably has a wiring problem.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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