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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 09-01-2013, 01:29 PM   #1
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Join Date: Mar 2011
Location: Berlin, MD
Posts: 13
My Ride: 2001 325i
Check Engine lite

ok ...so got infamous Check Engine lite a while back...car started stalling when stepped on gas at say stop lite....would run fine later that day as i would leave work but by time i got home 6 miles would be back to stalling at lite unless kept revved to over 2500

Ran codes...P0171 & P0174...did some research and seems to imply some thing like most likely a vacuum leak or maybe mass air....i could not find leak..but im idiot so bought it to shop who looked and couldn't find it..erased code...ran in driveway for 3 hours no prob no code.

code popped up next day...so did stalling..followed d one post that suggested disconnecting MAF and if works that was problem..disconnected adn ran great...so i replaced MAF.

Same problem...runs fine wo MAF plugged in but stalls with it connected. still getting codes ( plus additional for disconnected MAF)...i have changed plugs....done sea foam..i do have another post about my gas tank leak that has now mysteriously resolved...again it runs great wo MAF sensor but even after replacing it problem recurrs

Any one encounter something similar?
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Old 09-04-2013, 12:53 AM   #2
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Join Date: Sep 2013
Location: USA
Posts: 2
My Ride: 323i
Elusive rough idle issue

I have the same issue. If I un-plug my MAF, the car runs fine, it''s the only way I can drive and get to work. With the MAF sensor plugged in, the car idles all over the place, stalls at a light or quick stop, popping sound like a misfire under the hood on occasions. I've found the infamous oil seperator tube that attaches to the dip stick broken in half. Thought that would solve my problem, but it didn't. I've cleaned the throttle valve with carb cleaner, replaced the cam shaft sensors (2), bought an aftermarket MAF on Ebay, ($45), and still doesn't run right. I figured that if it runs better when I unplug the MAF, then that must be the issue. Took it to my local mechanic, and he seems to think the same thing. Cheap aftermarket MAF sensors are not worth the money I guess. I have sprayed chock cleaner around the areas where the CCV valve and hoses are, and I don't think there is any vacuum leak issue, all seems ok.

I just went to the local junk yard and asked if they had any 1999 to 2001 Hyundai Sonatas. Told them I need a MAF Sensor. Apparently the MAF's for these cars are an exact match for the BMW 323i 1999-2001 also! I plan on installing tomorrow to see if it solves my problem. The local BMW dealer wants $511.00 for a new MAF ! Screw that... I got the used junk yard MAF for $35, but found out it's from a 2002 year Sonata. Some of the numbers match up with the BMW MAF, but I'm going to see if it works, if not, I can take it back and get on from a 2000 Sonata. The worker pulled the wrong one from a 2001 instead of a 2000 by mistake.

Got my fingers crossed. I am also going to replace a leaking valve cover gasket and add 6 new plugs while I'm at it, (Bosch 4+ Platinum) At this rate, with all the new parts I'm putting on (also installed a new water pump, 4 hoses, thermostat, new belts, due to coolant leaks) might has well keep it!

I'll let you knkow how it works out...

Last edited by profitgen; 09-04-2013 at 12:57 AM.
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Old 09-05-2013, 09:00 PM   #3
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Join Date: Sep 2013
Location: USA
Posts: 2
My Ride: 323i
Update to above post...
Stopped by the local junk yard and asked if they had any 1999 - 2001 Hyundai Sonatas. They had 3, so I asked if they would pull the MAF Sensor from a 2000 for me, then I asked how much... ready for this... $35 !

Well, he pulled the maf sensor from a 2002 Sonata, instead of the 2000 year. I looked at the numbers on the side of the MAF sensor, and the Seimens number matched up, almost.. they are supposed to be the same exact maf sensor as the 2000 323i bmw, so I told them since it was from a 2002, and not a 2000, I would try it and if it worked, if not, I could return it and they would pull the one from the 2000 Sonata.

I yanked out the old maf sensor and installed the junk yard maf from the 2002 Sonata and it works like a charm ! Everything is now normal... Even the gear symbol next to the trans letter on the dash is gone. Steady rpm gauge, no trans clunk sounds, good acceleration.

Here's a hint. Before you install the maf, open the trunk and disconnect the negative battery cable, then install the maf sensor, hook up the negative battery cable and then fire it up. Sweet ! I have my car back from the dead...

The defective maf in the car had one of the 2 inside wires completly melted down. I got that one off Ebay, lesson learned I guess. Piece of junk, only paid $60 for it.. Total waste...

Then next day I passed the same junk yard and grabbed another Sonata MAF Sensor for $35 as a back up, just in case I ever need one. By the way, my local BMW dealer, bless their heart, wanted $511 fro a new MAF Sensor !

I was also going to try installing new spark plugs, and bought the Bosche +4 platinum plugs. After reading comments from this forum, I almost made a mistake... Do Not Use These Bosche Plugs ! They are junk and will cause your BMW to have misfires, poor idle, surging, and on and on. Get the NKG Irridium Platinum plugs instead... I exchanged them this morning and will install them tomorrow. The car is running so much better now, I almost want to hold off installing the new plugs, don't want to risk messing up a good thing.

So I guess the lesson here is go to your local auto junk yard and see if they have any 1999 - 2002Hyundai Sonatas and then grab the used MAF Sensor and install it on your car to see if the MAF is the issue. It solved my problem. Just a note. The only way I could run the car without getting stuck was to disconnect the plug on the MAF sensor. As long as the plug was left disconnected, the car was running ok, but the trans clunked when shifting gears, showed the gear symbol on the dash next to the "D" indicator. Go get yourself a used junkyard MAF from a Hyundai Sonata... Hope this helps someone solve their problem... Good Luck !

Last edited by profitgen; 09-05-2013 at 09:06 PM.
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Old 09-05-2013, 09:27 PM   #4
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Join Date: Sep 2012
Location: Georgia Peaches
Posts: 201
My Ride: Batmobile
Check Engine lite

The only light that currently works in my e46 is the check engine light

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Daily: Honda Fit EX 6-MT
PITA: 330i e90 6-MT
Past: 328i e36, 323i e46 Both Automatics
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