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///M3 Forum
The BMW E46 ///M3 is the M version E46 and puts out an amazing 333 HP and 262 lb-ft of torque at stock specs! There are an amazing amount of modifications for both the coupe and convertible models so read up and get started modifying your cars today!

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Old 05-28-2014, 03:26 PM   #1
ScorpionM3
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Join Date: Apr 2014
Location: Miami
Posts: 3
My Ride: E46 m3
Another e46 m3 MAF issue

Hey everyone, Im a noob to this forum looking for a hand. Any feedback would be appreciated.

My e46 M3 idles perfectly 99% of the time, and runs strong as hell, but every once in a while when Im driving I clutch in (all the way in, guys I know how to drive a 3 pedal) and the motor goes to idle, pauses a moment and then dies. It also has some general weirdness (a bit of buck as if its missing) at 1% throttle. Other than that it runs great (such an m3 phrase).

Im pretty good at diagnostics and have been chasing my tail and ignoring the MAF under the assumption it would run much worse with a bad MAF, particularly at idle...

What I know -- fuel seems to be getting there fine. The pump and regulator are solid. Injectors I cannot say for sure, but the car gets full throttle straight to redline and feels over the printed horse, so I doubt its fuel. I not only checked for vacuum leaks (needlessly since theres no surging or rough idle) and even did the old trick of shooting carb cleaner around the seals (including injector seals, TB seals, manifold, intake arm and boot, et cetera) to see if there was surging from the draw in of nice flammable chemicals. Nothing there. I have checked over the VANOS maintenance (have not yet tried replacing the CAS's but I do not think the problem is there either). The TB's and IAV are spotless and have been cleaned again anyway, but I didnt think that to be the case either since it does come back to idle and pause before dieing, which should mean the IAV is working properly.

Finally I unplugged my MAF and it seems to have solved the problems altogether (aside from now giving me an SES light for the first time ever (no prior codes)). Normally I'd run out and get a MAF, but every time I see you guys chattering on the forum its never the MAF. Hell, I understand that its now on a "rich" map and that could just be overshaddowing any other potential problem. Also of note, I have cleaned the MAF specifically with MAF cleaner twice with no change. I do not have a service manual, can anyone tell me if I can use a multimeter to just test the damn thing before spending a few hundred bucks? Any other suggestions? Anyone want to chime in and let me know if you agree its probably electrical with the computer being fed something wrong from a sensor? Input is appreciated...

Thanks everyone.
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Old 05-29-2014, 12:14 AM   #2
Teslazerok
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Location: Saskatchewan, Canada
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My Ride: 2003 M3 6SPD
Know anyone with an M3 that is willing to swap MAF's with you for a day? That would be the quickest most accurate way to test it. Try asking in your regional forum.
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Old 05-30-2014, 09:02 AM   #3
ScorpionM3
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Join Date: Apr 2014
Location: Miami
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Thanks -- Im trying to locate one now.

As a note, all of a sudden with no MAF my car started cutting and threw an SES -- I immediately plugged my MAF back in and its back to running like it did before. No idea why I got such a random transition...
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Old 05-30-2014, 11:35 PM   #4
Antiviruz42
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My Ride: 2003 ///M3 Wrapped
Had some similar issues as you. posted a thread about it. Hopefully save you a little trouble and get you a fix. Maybe not. If Ive learned anything its that the same fix for a problem does not always help everyone. Post up any update!!


http://forum.e46fanatics.com/showthread.php?t=1013659
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Last edited by Antiviruz42; 05-30-2014 at 11:35 PM.
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Old 06-02-2014, 08:58 AM   #5
ScorpionM3
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Join Date: Apr 2014
Location: Miami
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My Ride: E46 m3
Thanks, Antiviruz.

I took a read through and our problems are quite similar. I have tried to find a vacuum leak, but I have been unsuccessful -- that said I will pull my airbox and try again... No luck on locating a borrowed MAF so far...

Also of note, I noticed on your thread that someone made a crack about German rubber going bad and hoping that those Germans don't make contraceptives... couldn't agree more!

-M
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