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Old 03-21-2017, 01:59 PM   #1
JAMESphysique
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E46 Bad MAF. Clean it or Replace ?

Found out I have a bad MAF. Should I replace or clean? I don't know if it usually starts to work if you clean it..
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Old 03-21-2017, 02:02 PM   #2
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Quote:
Originally Posted by JAMESphysique View Post
Found out I have a bad MAF. Should I replace or clean? I don't know if it usually starts to work if you clean it..


If it's bad, I'd just replace it.
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Old 03-21-2017, 03:09 PM   #3
mtnbimmer
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Originally Posted by JAMESphysique View Post
Found out I have a bad MAF.
If it's bad what good would cleaning do?
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Old 03-21-2017, 03:46 PM   #4
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How do you know it is bad? An Asian counterfeit MAF is always bad!!

I rarely see a totally failed MAF, most are degraded and under report due to aging.

What problem(s) are you trying to solve?

Cleaning a MAF is pretty much a waste of time and money.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

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Last edited by jfoj; 03-21-2017 at 03:46 PM.
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Old 03-21-2017, 03:48 PM   #5
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How do you know it's the MAF? Codes?

Plenty of misdiagnosed MAFs, as it's easy to confuse it with a vaccum leak.

Especially if the technician isn't bmw specialist.

They sell a lot of MAF cleaner, it's cheap, rarely successful, but worth a shot.

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Old 03-21-2017, 04:46 PM   #6
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An 01 that's pretty old. Replace the MAF. FCP oem cost me $230 ish. Literally solved everything. LTFT are at zero and no cold start stumbling.
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Old 03-21-2017, 04:50 PM   #7
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An 01 that's pretty old. Replace the MAF. FCP oem cost me $230 ish. Literally solved everything. LTFT are at zero and no cold start stumbling.
was that the siemens/VDO? Who makes the genuine BMW one? any idea?
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Old 03-21-2017, 05:26 PM   #8
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Seimens/VDO at FCPEuro with price match is like $140.
Do a search
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Old 03-21-2017, 07:44 PM   #9
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Originally Posted by JAMESphysique View Post
Found out I have a bad MAF. Should I replace or clean? I don't know if it usually starts to work if you clean it..
Unless you drove over it or otherwise trashed it, I suspect it may be fine, but "other information" makes you think the MAF is the culprit.

Sooooooo, why do ya think it's bad?
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Old 03-31-2017, 05:21 PM   #10
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When on cold start its disconnected it idles perfectly, but when I reconnect it, it rough idles hard AF and sometimes turns off.
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Old 03-31-2017, 05:28 PM   #11
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Leave the MAF alone, read this at least 3 times: Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616
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Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 03-31-2017, 05:32 PM   #12
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...disconnected it idles perfectly, but when I reconnect it, it rough idles hard AF and sometimes turns off.
This is the very logic and troubleshooting we (5 years Tech Support for me) used in diagnosing computer issues. If it doesn't work when it's plugged in and it does work when it's not plugged in, you have generally found out what is not working correctly.
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Old 03-31-2017, 05:47 PM   #13
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This is the very logic and troubleshooting we (5 years Tech Support for me) used in diagnosing computer issues. If it doesn't work when it's plugged in and it does work when it's not plugged in, you have generally found out what is not working correctly.
This is not the case with Engine Fuel Management systems.

Unplugging the MAF will cause most DME/ECU/ECM to fall back to a default fuel delivery MAP that is Richer than when the MAF is connected. What this typically does is MASK Lean problems due to vacuum leaks. Most engines default to a Richer mixture to keep the combustion chamber temperatures lower to protect the engine from damaging detonation.

But you guys decided what you want to do.

Keep in mind you are a FOOL to buy a used MAF, a cheap MAF from ebay or a $50 MAF from the local auto parts store. There are also A LOT of Asian counterfeit MAF's that are often sold for in the $50-$75 range and some are even sold at the same price as name brand parts and will often be in name brand boxed, have official looking stickers and logos cast in the housing. These will cause you all sorts of headaches.

The MAF is the single most sensitive and important sensor on the engine for determining fuel delivery. Measuring the weight/density of air is not a simple and easy task.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 03-31-2017, 05:50 PM   #14
JAMESphysique
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Thanks for all the advice everyone ! I deff won't buy cheap eBay junk. Quick question, will 2003 CI struts, control arms, links fit 325i 01 ? thank you for any advice
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Old 03-31-2017, 05:57 PM   #15
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No convincing evidence the MAF is bad and needs to be replaced at this point.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299

Last edited by jfoj; 03-31-2017 at 05:59 PM.
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Old 03-31-2017, 06:33 PM   #16
JAMESphysique
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An 01 that's pretty old. Replace the MAF. FCP oem cost me $230 ish. Literally solved everything. LTFT are at zero and no cold start stumbling.
lol. Its old but getting it for 500 with 120 something thousand miles is a steal. Plus, making it a project.
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