MAF Removal and Cleaning (2000 540i and 2001 525i)

[jamesdc4]

Here are the two posts with the step-by-step and the pics. (I'll have to copy and photobucket Jason's pics because they are attachments.)

2000 540iA

FINALLY, 2000 540iA MAF Location and removal pictures...!

(1) MAF Location to the right of the air intake.


(2) Pinch and wiggle MAF Electrical Connector to remove...be firm but gentle, it's expensive.


(3) MAF Electrical Connector removed...


(4) Remove MAF Torx T-20 Security Screws (2)...


(4a) See?!? Two of 'em...and notice I've pushed the MAF EC to the side.


(5) Lift straight up to remove the MAF unit...


(6) There you have it...use CRC MAF Cleaner and Q-tip soaked in cleaner, dry and reinstall FTW!


Save some money...clean it first and only replace it if you are still receiving poor performance or CEL. It's an easy DIY and took me WAY less time than taking the pix and documenting it for you. Enjoy...

2001 525i

2001 525i MAF Location and removal pictures...!
There's the little guy... to the right of the dip stick...


Loosen intake boot clamp by using a screw driver



Disconnect harness connector (the plug to the right of the MAF)
(press on the silver wire latch and pull plug)


Release clip from air filter housing
Carefull! The plastic around the clip breaks easily.
Mine seemed to be broken from the dealer...


Wiggle the MAF out from the rear air intake tube




Wiggle out the air intake housing infront of the headlight



There she blows!
She's FREE!
MAF at last!


The rear of the MAF
you can see the module beyond


These steps are pretty much out if the Bently.

Now use the CRC electric or MAF spray that can be bought from AutoZone, or where ever, and spray the crap out of the housing and inside.

I am going to try Q-tips and the CRC cleaner, real carefully, and clean the module inside the MAF housing.

Let dry.

Re-install

Thanks "Cool Dude" for the SUPER knowlege and always helping!

Jason

Original MAF thread.

Special thanks to 12cooldude, Jason5driver for the write-ups, and also to Gumbi4u for placing this in the DIY section!

[ray5]

My car shows herratic idle and stalling, after I cleaned the MAF, problems did not dissapear so I decided to install a new one and problem got worse, bad acceleration (motor stalling when accelerating normally), I have disconnected the MAF and motor runs OK...?!!?
Thanks.... Ray5

[jamesdc4]

Ray,
Welcome to Bimmerforums.

Did you buy an aftermarket MAF or did you purchase an OEM one? Aftermarket MAFs have been known to cause problems.

[ray5]

Hi and thanks for welcoming me and for answering my question!

I bought a OEM on Ebay, the "power seller" has over a thousand good comments from BMW, Audi and VW owners concerning the MAF OEM he sells. The heretic idle appeared the same day that once a while not all the time. After a week or two, stalling engine occured suddenly when depressing 1/3 the gas pedal, like if there was no gas at all coming to the injection.

Sorry for my English, I'm doing my best!
Thanks again!
Ray

[LarsHH]

Try to shift the Camshaft Pulse Generators at the same time and do a diagnostics on your car

[mattmartindrift]

a little late, but you may want to check the intake area over for any vacuum leaks.

[ssanmor]

Thanks for the tip!
Did you really notice any difference in the 525i after cleaning the MAF? Thanks!

[NNY528I]

I really dont like the first procedure that is included here, it is a really easy way to destroy a MAF sensor, you should NEVER EVER touch the element in a MAF it is very sensitive and very precise and it is very easy to damage or tweak it and find yourself needing to purchase a new sensor, I would follow the second procedure only WITHOUT using any type of quitip or swab, just flush with cleaner is all that is needed.

[mrgoodcat66]

so would you recomemnd just spraying the cleaner over the unit without touching or rubbing the cleaner on the maf to get it clean?

[jamesdc4]

I believe the directions were from the CRC MAF cleaner manufacturer.
You could just spray the sensor first and see if that yields positive results. If that doesn't work, move on to the Q-tip approach.

[ViolinARC]

I really dont like the first procedure that is included here, it is a really easy way to destroy a MAF sensor, you should NEVER EVER touch the element in a MAF it is very sensitive and very precise and it is very easy to damage or tweak it and find yourself needing to purchase a new sensor, I would follow the second procedure only WITHOUT using any type of quitip or swab, just flush with cleaner is all that is needed.

It's worked for my successfully twice now so it's a matter of being uber careful IMO but I understand your point.

so would you recomemnd just spraying the cleaner over the unit without touching or rubbing the cleaner on the maf to get it clean?

It's ultimately up to you but after a few good sprays, I was still able to get quite a bit of dark gunk off my MAF with the q-tip. If you choose to do it this way, just be UBER careful (that's two warnings in one post).

[NNY528I]

Here is why I don't like that procedure just FYI.

http://forums.bimmerforums.com/forum....php?t=1535197

[jnyost]

I've seen it do more damage than good. Usually ends up in the sale of a new MAF.

[jamesdc4]

Here is why I don't like that procedure just FYI.

http://forums.bimmerforums.com/forum....php?t=1535197

I'm on board with you on not touching the sensor in any way, but the DIY instructions posted by 12cooldude I believe, were on the CRC can. I would reserve the Q-tip for when spraying the MAF yields no improvement.
Also, crdiscoverer's post isn't a good one to use as an example.

Well, I was far from gentle with the q-tip. Try not to be dumb.

[crdiscoverer]

Ha! I feel important.

But seriously, for all of you that will read this DIY in the future. Avoid touching the sensor with anything. Spraying is alright, but nothing more. The sensor is composed of two very thin metallic filaments, less than 1mm thick. Even with a slight amount of pressure they break into pieces and that's enough to kill the MAF.

[NNY528I]

one has to consider that better than 75% of the people who use DIYs like this have limited knowledge of cars and mechanical things in general. while someone who is very mechanically oriented might understand this intuitively there are a whole HELL of a lot of people out there who have absolutely no f'ing clue WTH is going on and as such I like to make sure the instructions we provide are as idiot proof as possible.

[jamesdc4]

one has to consider that better than 75% of the people who use DIYs like this have limited knowledge of cars and mechanical things in general. while someone who is very mechanically oriented might understand this intuitively there are a whole HELL of a lot of people out there who have absolutely no f'ing clue WTH is going on and as such I like to make sure the instructions we provide are as idiot proof as possible.

I hear you, Jason. I'm the same way. A lot of members will post things like, "that's such an easy procedure...blah, blah", but I feel they aren't taking into account the variety of people and their automotive experience (or lack of). That's why my DIYs are absolutely step by step. I don't like to leave out a step that might send a noob into a tail spin.
Thank you guys for your contributions. They help people like me who feel more comfortable with every step documented (well maybe sans the steps on breathing or having a beer ).

[bigjoe87865]

I have read the warnings
I still want to do this... No CEL or anything... BUT... the car is a 97 540i .. being 13 years old and im sure its on the original MAF.. so its gotta be dirty.


anyways... I ONLY want to spray with the MAF cleaner, I dont want to Qtip anything.

but is removing the MAF and only spraying it down still bad?.. Or should I leave the sensor in the plastic MAF housing and spray from the sides?

like this

[jamesdc4]

but is removing the MAF and only spraying it down still bad?.. Or should I leave the sensor in the plastic MAF housing and spray from the sides?

Remove the entire MAF and housing. No need to remove the sensor from the housing if you are only going to spray it.

[dbiMMer10]

I agreed with the MAF DIY procedure by "james4dc". nice write up

I did mine 3 months ago and I do this at least once a year, while checking the air filter. just for a small preventive measure.

just adding to MAF DIY, you want to do this when the engine is cold, prior starting/driving the car. like in the morning or when you just want to do something during your day off or to get away from your opposite sex mate

[jamesdc4]

I agreed with the MAF DIY procedure by "james4dc". nice write up

Special thanks to 12cooldude, Jason5driver for the write-ups

[Jim530i]

Did it today on my 530i, while it is not so hard people will need to be cautious as it is very fragile.

I sprayed the sucker down good. Let it dry and spray some more. After its dried again, sprayed some more again, till I was happy with no more dirt inside.

After drying and installing it, went on the highway a felt the torque is more stronger. I don't know if its because I think it should pull more power, but it definitly felt alot smoother....

It was hard to get a hold of the CRC MAF cleaner, till I found a shop in Hong Kong that has it. I drove from China to Hong Kong ~100km round trip for that sucker...

Now that I know its really good, I'm gonna go back when I get to Hong Kong and stock up on this MAF cleaner, good stuff.....

[sappw1]

In removing mine i accidently broke off the plastic bullsey piece on the back.. do i need to replace the whole thing now or is it fine without it?

[Vatoman]

Id like to update this a bit pertaining to the 525i/m54. When going to remove the airbox make sure to loosen the screw next to the maf on the left side by dipstick. Also watch out for your driving lights connector. I pulled the maf directly out instead of wiggling out the whole airbox. Note theres a rubber gasket thats rests inside the airbox where the maf plugs in it could fall make sure thats in place. My maf was spot less cleaned it let it dry for about 15min before I started the car. Take your time lots can go wrong if your not being careful when removing the box its tight in that area.

[BUFLOsolja]

so i'm trying to clean my maf sensor for a recurring SES light ... i went out and bought some torx bits but not "security" torx bits (!!), so i resorted to removing the entire housing just to have a look ... the little guitar string electrode looking things look pretty clean to my eye, the metal looks shiny along their whole length but i'm still going to spray the entire thing down ... is it possible that the sensor is bad without being dirty? ... i was getting misfire codes initially, so i thought i needed new O2 sensors or worse case, new cats ... but i had the car in storage for a few months and when i took her out, the battery had died ... i did some tuning up (oil, brakes, adjusted parking brake) since i needed the new battery anyways and then shortly after, i got codes for bad air/fuel mixture when the SES tripped again so i was hopeful all i needed was a new or cleaner MAF sensor instead of new O2 sensors and/or a new cat ... as far as symptoms, i have a finicky idle @ low rpm with occasional stalling also @ low rpm ... before i had the car in storage, the misfire was prominent right around 4k rpm, i'm not noticing a misfire since storing, but then again, i've been babying her ... a bad MAF sensor makes sense for the idling & fuel/air symptoms, but would it also explain misfiring cylinders, perhaps from running to lean? ... also, does anyone think that these symptoms could be tied to a squeaky idle/idler pulley? ... i thought initially the issues were unrelated, but after taking the car out of storage and getting her up and running again, both problems disappeared for awhile, but they've reared their ugly heads again, seemingly at the same time ... any thoughts/input are greatly appreciated