TECH: Clean your MAF, don't replace! - BMW M5 Forum and M6 Forums
M5 E39 and E60 tips & tricks Forum for tips, trick, ideas, and other "home made" improvments and enhancements.

LinkBack Thread Tools Rating: Thread Rating: 3 votes, 5.00 average. Display Modes
post #1 of 59 Old 2nd September 2003, 06:10 AM Thread Starter
m5board.comoholic (>1000 posts)
louv's Avatar
Join Date: Jan 2001
Location: Los Gatos, CA
Posts: 1,600
Thanks: 0
Thanked 21 Times in 14 Posts
Thumbs down TECH: Clean your MAF, don't replace!

If you are having Air-Fuel mixture problems... Clean your MAFs.

Here's How

A couple of months ago my car started throwing a long series of fault codes, and lighting up the SES light.

- at full throttle, like passing another car on an uphill, the Beast would drop into a limp-home mode.
- when idling it would occasionally stall
- car misfired and ran rough

Well, my dealer charged me 2 hours labor to investigate, eventually finding a vacuum leak, and then reset the fault codes. Well, $200 bucks lighter, the car threw more fault codes on the way home.

They suspected I would need to replace both MAFs. Cost? $407 per MAF. Yikes! And they weren't even sure that would fix it.

Well, I've been out of warranty for over 10K miles, so I didn't really want them spending more of my money to experiment with a fix. On their dime? Sure. On mine? Thanks, I'll do the experimentation.

So I bought a new MAF ($274 by mail) and swapped it in. Bingo! No more stalling, and runs much better at full tilt!

Well, I thought to myself, a while back somebody mentioned on the board that the K&N filter's oil had fouled their MAFs. I don't use K&Ns, but I'm sure after 60k miles there's some dirt in there. So I figures I'd clean out the old one and swap it back in.

All clean, replaced on the car... and... It Runs Great!

Dirt is your enemy.

Careful cleaning is your best weapon.

My solution might not fix your problem. Your mileage may vary. Blah, blah, blah.

'01 Tundra, '15 X6M, '15 i8, '15 Miata
'09 R1200GS-Adv, '10 G450X

louv is offline  
The Following 3 Users Say Thank You to louv For This Useful Post:
-BEASTMW- (11th April 2009), OlieL (14th April 2011), Torquey5 (14th August 2010)
Sponsored Links
post #2 of 59 Old 2nd September 2003, 06:19 AM
Member, Sport: Off DSC: On (>50 posts)
sveilside's Avatar
Join Date: May 2000
Location: In front ....:)
Posts: 100
Thanks: 0
Thanked 0 Times in 0 Posts
sveilside is offline  
post #3 of 59 Old 2nd September 2003, 06:29 AM
m5board.comoholic (>1000 posts)
XrayMD's Avatar
Join Date: Aug 2002
Location: Marietta, OH
Posts: 1,553
Thanks: 0
Thanked 3 Times in 3 Posts
Good stuff! Thanks for the instructions! Might not be a bad idea to clean them every 6 months or so I would guess.

'02 M5 LeMans Blue:

Active Autowerke CAI/brake ducts
Supersprint Headers and cats
SuperSprint exhaust with X-pipe
Evosport custom 3.45 diff. with 30% lockup and 2x dynamic lockup
UFMotorsport intake air temp sensor relocation
Powerchip Gold (SS header/cats version)
Ignition Solutions plasma coils
Dinan Stage III suspension
BeastPower sway bar brackets
Dinan front strut tower brace
Stoptech Custom Silver Big Brake kit (fronts)
RMS short shifter
Rogue Performance transmission mounts, Royal Purple Synchromax fluid
Llumar window tint (35%)
XrayMD is offline  
The Following User Says Thank You to XrayMD For This Useful Post:
Frye (27th December 2008)
post #4 of 59 Old 2nd September 2003, 06:35 AM
M5 Expert (>4000)
greg's Avatar
Join Date: Mar 2000
Location: Geyserville, CA, USA
Posts: 5,239
Thanks: 1
Thanked 42 Times in 23 Posts
Don - GREAT JOB! I think you did everyone here a great service. Thanks for taking the time to document it so thoroughly! My MAFs were replaced (under warranty, fortunately) recently - and although my symptoms weren't as severe as yours, I also felt an improvement in performance - more power and smoother.

If I had known how easy it was I would have serviced them myself.


1) Simple Green is highly alkaline, and is known to cause corrosion when it isn't completely rinsed away. I think your idea to use the alcohol is sufficient, but I would caution people to be sure to do a thorough rinse - you want no traces of SG left around. I'd be willing to bet someone here with a strong background in chemistry or automotive science can recommend a better solvent.

2) Vaseline is usually a BAD lubricant for rubber parts. It is a petroleum product and can cause these parts to swell. You would be safer to use a silicone-based lubricant. You can get a tube that will last you the rest of your life at any swimming pool supply place - it is used for all the o-rings in pool filter systems.

'00 M5 - The Ultimate Ultimate Driving Machine! Greg's M5 Page
'01 996 TT - Greg's Porsche Turbo Page
'00 A6 4.2 - doesn't deserve a web page
greg is offline  
The Following User Says Thank You to greg For This Useful Post:
Frye (27th December 2008)
post #5 of 59 Old 2nd September 2003, 01:07 PM
madmax's Avatar
Join Date: Jul 2002
Location: NSW - Australia
Age: 56
Posts: 39
Thanks: 0
Thanked 0 Times in 0 Posts
Pardon my ignorance, as items are often called something else in other countries, but what is simple green ?

Thanks for the great post and info.
I just had my both mafs replaced under warranty 3 weeks ago and yes the beast does go and pull much harder.

2002 Carbon Black/Silerstone M5 Beast
Powerchip Gold Ver2
DF Motorsport temp sensor relocation kit
Evosport UD Power pulleys/Fan delete
Nowack style underside insulation of plenum
BMC Carbon Dynamic Air Box System with Ram CAI
4>2>1 Ceramic coated custom hand-made s/steel headers and hi-flow cats
Plasma coils, Rennsport velocity stacks
Supersprint X-pipe and SuperSprint mufflers
UUC SSK, Rouge performance mounts, RP Synchromax
KW Varient 2 Coilovers, BeastPower rear brackets
Stoptech 4 wheel big brake kit with front brake ducts
ACS Metal pedals, Momo s/steel gearshift
Hamman front splitters, 70% window film
Dronell Type II wheels 8.5x19f & 10x19 r with 245f / 275r Yokohama AVS tyres
3.64 ratio Quaife diff change
madmax is offline  
post #6 of 59 Old 15th September 2003, 02:50 AM
Member, Sport: On DSC: Off
tampa_M5's Avatar
Join Date: Sep 2003
Location: Tampa FL
Age: 36
Posts: 230
Thanks: 0
Thanked 1 Time in 1 Post
very informative on a topic that counts!!!! immediately after putting in the AA CAI and recleaining my K&N's one MAF sensor had gone bad on my 2000 with only 25K miles on it, but the dealership had replace it under warranty. I did suffer from the problems described. a couple weeks ago, the other one had gone bad, no symptoms, but a SES light did come on and off a week before....once again under warranty....but with the use of this post and the GREAT pics....this will solve the problem for most of us, especially if out of warranty!!!

Simple green is a good cleaner, but it does seem to have a tough residue on whatever its used on.....the alcohol is good as an afterwash to force a quick drying effect on the sensor.....maybe a strong but gentle dish soap would be a better Dawn??

Greg, you are a GENIUS....i swear. I have only recently been able to post to the board, just been too busy, but occasionally before i would always view the topics especially before doing a mod, or giving up to the have a lot of real knowledge and we are fortunate to have you sharing this with us!! .....also, not to forget the other great contributions from the moderaters and the members!! together we make up an unbelieveable database of info on this great machine.

also, Greg, good luck and thanks for taking the time to do the detailed experiment with the UFM temp sensor.
Thanks to everyone

tampa_M5 is offline  
post #7 of 59 Old 20th September 2003, 11:25 PM
Member, Sport: Off DSC: On (>50 posts)
volcanom5's Avatar
Join Date: Jan 2003
Location: Volcano, CA
Posts: 96
Thanks: 0
Thanked 0 Times in 0 Posts
Louv just saved me some bucks!

Same BS runaround with the dealer. Just cleaned my MAFs as noted in the excellent instructions and the difference is night and day.

- cold start is MUCH smoother now, very little hesitation
- acceleration overall is smooth and strong again

Tampa_m5, you could not be more right about the value of this board.


02/00 M5 Titanium Silver w/Powerchip

Last edited by volcanom5; 20th September 2003 at 11:26 PM.
volcanom5 is offline  
post #8 of 59 Old 3rd October 2003, 05:13 PM
M5 Expert (>4000)
MAH's Avatar
Join Date: Jun 2000
Location: Houston (Cypress) Texas
Posts: 5,227
Thanks: 37
Thanked 41 Times in 29 Posts
Great Post


I just love this kind of common sense information. A screw driver, some electrical contact cleaner, perhaps Simple Green and your done in half an hour. Cool .

That being said, I have had the K&N filters for 10,000 miles with no ill effects. Still, it doesn't hurt to know about this procedure and keep it for future reference.

Thanks guys,

MarkAttention moderators - I feel this thread needs to be perminantly placed in the best of threads.

MY2001 Imola Red
Lux. Black Interior
Painted Calipers,
AC Schzitner Type III Two Piece 18 chrome wheels, Stage II HID's Low Beams and Foglights, Supersprint X-pipe (removed).
Autowerke CAI
Powerchip Software Upgrade
Stage I upgrade MB Quarts Speakers from Bavarian Soundwerks (our sponsor here)
Tubi Catback Exhaust
425HP and growing!
Red (angry eyes) Angel Eyes

Last edited by MAH; 3rd October 2003 at 05:17 PM.
MAH is offline  
post #9 of 59 Old 28th October 2003, 10:18 PM
Member, Sport: On DSC: Off
Join Date: Jun 2003
Location: PA
Posts: 235
Thanks: 0
Thanked 0 Times in 0 Posts
Originally posted by madmax
Pardon my ignorance, as items are often called something else in other countries, but what is simple green ?

simple green is a degreaser that is supposed to be biodegradebale
marinakorp is offline  
post #10 of 59 Old 30th October 2003, 12:16 AM
M5 Expert (>4000)
Ahmed's Avatar
Join Date: Aug 2003
Location: Manama, Bahrain
Age: 42
Posts: 6,352
Thanks: 1,374
Thanked 590 Times in 429 Posts
i read it....
i understood it...
i acknowledged it....
i did it.....

there's one thing left to do.... and that is...


THANK YOU FOR SAVING US ALL THE TROUBLE OF DEALING WITH THE DEALERS and ofcourse saving us hundereds of dollars!

Thank You once again!

2013 C63 AMG P31
2009 Lexus GS460
2004 Acura NSX-T
1994 Ferrari 348 Spider
1993 Dodge Viper RT/10 Roadster
1980 Porsche Turbo 3.3

Last edited by Ahmed; 30th October 2003 at 12:17 AM.
Ahmed is offline  
The Following User Says Thank You to Ahmed For This Useful Post:
NGKM5 (29th October 2013)


Quick Reply

Register Now

In order to be able to post messages on the BMW M5 Forum and M6 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes Rate This Thread
Linear Mode Linear Mode
Rate This Thread:

Similar Threads
Thread Thread Starter Forum Replies Last Post
KN filter and MAF....Lost power? Gaspasser E39 M5 and E52 Z8 Discussion 11 18th January 2015 03:22 PM
TECH: Clean your MAF, don't replace! louv E39 M5 and E52 Z8 Discussion 42 12th November 2010 12:45 PM
Stereo, Sub, Woofer, DSP, Pin, Bass, Speakers V-10 4 Me E39 M5 and E52 Z8 Discussion 0 26th September 2003 07:54 PM
TECH: tire life. when do you know to replace your tires? young-nyc E39 M5 and E52 Z8 Discussion 12 14th June 2002 11:47 AM
Stop tech Big brakes or Brembo. Rave E55 E39 M5 and E52 Z8 Discussion 0 15th January 2002 03:32 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome