BMW M5 Forum and M6 Forums banner

1 - 20 of 29 Posts

·
Registered
Joined
·
170 Posts
Discussion Starter #1
Just cleaned my MAFS with ElectroWash. Geez - what I have been missing. The BEAST is definitely back. Super pissed off, snarling and spinning wheels all over the place! :hihi:

I definitely picked up some lost power! :M5launch:

The bolts holding in my MAFS are 6 point security Torx and the wrench I bought was at Sears for $19.00 - it was actually a driver with a bunch of bits - 5 bits being Torx Security in various sizes.

This is a very easy maintenance task - and since the PO had K&N's in when I bought the car I really wanted to give the MAF elements a good cleaning.
I left the air intake tubes in place and just pulled the MAFS out and cleaned them - dried them with canned filtered air - and replaced. 20 mins tops!

I know some guys have said the bolts securing the MAFS are a 5 point bolt - well my 2002 has a 6 point and the Sears wrench fit perfectly.

Anyway - if you feel like your beast has been a little sluggish of late - try this. Mine did not have SES lights - or rough acceleration like some board members - it just felt a little down on power. This certainly made a difference.
 

·
Registered
Joined
·
170 Posts
Discussion Starter #3
Well - here is how I did it:

1. Remove the electrical connectors from the MAFS. It is a simple squeeze and pull movement and the electrical connectors pull off from the MAF unit.

2. Using the Torx wrench - unbolt both MAFS and pull out of the intake tube.

3. I sprayed Chemtronics Electowash PX all over the sensors and wires and used a q-tip to carefully scrub the wires. I was VERY VERY gentle as the wires are delicate.

4. I then dipped in pure Alcohol (not Rubbing alcohol) to try and rinse off the contaminents - even though the Electrowash evaporates and leaves no residue - I still wanted to "wash off" any grease or dirt from the unit.

5. I then did another healthy spray of Electrowash and air dryed with canned air.

6. Reinstall the MAFS - there are arrows on the bottom portion that show you which way the air flow should be - and then reinstall the electrical connectors.

Done!
 

·
Registered
Joined
·
5,227 Posts
I will have to under take this procedure to see if I am missing anything. If it has been a slow loss of power I might never have realized what I was missing.

Thanks for the tip,

Mark
 

·
Registered
Joined
·
170 Posts
Discussion Starter #6
bayerischemotor said:
Well I guess if the meters would look clean it might be a waste of time, so I will also do this, but first check if the meters are infact dirty. My car has the original airfilters.
The slightest film or contaiminent can alter the readings for the MAF. If you go through the process of pulling it - you might as well clean it.

Mine didn't look "dirty" by any means. There seemed to be a small speck on one wire - and a barely perceptible film on the sensors. After the wash they were both gone.

As I said though - my M had the K&N's in for about 8,000 miles - and I wanted to clear off any oil residue that may have passed from the Filter to the MAF.
 

·
Registered
Joined
·
1,553 Posts
Well that's very interesting. Someone replaced your Torx security with 6 points then because they come with the "higher" security (and not readily available) 5-point Torx Security Plus. I too used the ElectroWasH PX and it is great stuff!!

:cheers:
 

·
Registered
Joined
·
104 Posts
Wrightsville Beast said:
Just cleaned my MAFS with ElectroWash. Geez - what I have been missing. The BEAST is definitely back. Super pissed off, snarling and spinning wheels all over the place! :hihi:

I definitely picked up some lost power! :M5launch:

The bolts holding in my MAFS are 6 point security Torx and the wrench I bought was at Sears for $19.00 - it was actually a driver with a bunch of bits - 5 bits being Torx Security in various sizes.

This is a very easy maintenance task - and since the PO had K&N's in when I bought the car I really wanted to give the MAF elements a good cleaning.
I left the air intake tubes in place and just pulled the MAFS out and cleaned them - dried them with canned filtered air - and replaced. 20 mins tops!

I know some guys have said the bolts securing the MAFS are a 5 point bolt - well my 2002 has a 6 point and the Sears wrench fit perfectly.

Anyway - if you feel like your beast has been a little sluggish of late - try this. Mine did not have SES lights - or rough acceleration like some board members - it just felt a little down on power. This certainly made a difference.
 

·
Registered
Joined
·
104 Posts
Hi: Thanks for the informative info on cleaning the MAFS. I also own a 2002/M5, Oxford Green/Caramel. Specifically, where are the MAFS located? I asked my BMW parts folks today and they were not sure. I will also clean my wife's MAF on her 2001/540i. Any thoughts are appreciated.

Tom
2002/M5
2001/540i


p.s. Where did you purchase the Electrowash??
 

·
Registered
Joined
·
5,227 Posts

·
Registered
Joined
·
551 Posts
I figured I'd resurrect an old thread that I came across by mistake after looking at people purchase the MAF's offered by bimmerzone in the group buy (http://www.m5board.com/vbulletin/m5-e39-group-buy-forum-sponsor-discussion-offerings/148202-bimmerzone-com-bmw-e39-m5-bosch-maf-sensors-group-buy-295-shipped-pair.html).

To be totally honest, I am clueless about MAF's and do not understand much as to how they operate and what purpose they actually serve. If cleaning them is sufficient, then I wonder if people have continued to apply this method with success.

Moreover, do after market MAF's differ in performance compared to OEM?
 

·
Registered
Joined
·
3,873 Posts
I figured I'd resurrect an old thread that I came across by mistake after looking at people purchase the MAF's offered by bimmerzone in the group buy (http://www.m5board.com/vbulletin/m5-e39-group-buy-forum-sponsor-discussion-offerings/148202-bimmerzone-com-bmw-e39-m5-bosch-maf-sensors-group-buy-295-shipped-pair.html).

To be totally honest, I am clueless about MAF's and do not understand much as to how they operate and what purpose they actually serve. If cleaning them is sufficient, then I wonder if people have continued to apply this method with success.

Moreover, do after market MAF's differ in performance compared to OEM?
In general, the MAFS (mass air flow sensor) contains a thermistor that has voltage applied to it. Some systems utilize a constant current setup and the voltage increase (or decrease) that is required to maintain the required current is extrapolated to determine an air velocity value. Other systems apply a constant voltage and measure the variance in current due to the change in resistance of the thermistor due to the change in temperature due to variance in air flow across it to extrapolate an air velocity value. In both cases the air-velocity value is used in conjunction with the (constant and known) area of the intake tube (MAFS housing) opening to determine the mass of air flowing through the intake tube.

They do degrade over time as any electrical component will so eventually they will have to be replaced. Cleaning them will not slow this degradation; it will only increase the period of time out of their entire service life that they, and therefore your vehicle, operate at "peak" efficiency.

There is plenty of anecdotal evidence to rule against any other than genuine Bosch MAFS. The only choices are whether to go with the Bosch part number directly related to the BMW M5 or to go with a very similar MAFS for some VW model. I have used the VW MAFS with apparent success but as to not turn this into another MAFS debate I will simply say that you will have no problem with the genuine Bosch M5 MAFS and Bimmerzone has them for an excellent price so there really no reason to get anything else.

-Josiah
 

·
Registered
Joined
·
551 Posts
In general, the MAFS (mass air flow sensor) contains a thermistor that has voltage applied to it. Some systems utilize a constant current setup and the voltage increase (or decrease) that is required to maintain the required current is extrapolated to determine an air velocity value. Other systems apply a constant voltage and measure the variance in current due to the change in resistance of the thermistor due to the change in temperature due to variance in air flow across it to extrapolate an air velocity value. In both cases the air-velocity value is used in conjunction with the (constant and known) area of the intake tube (MAFS housing) opening to determine the mass of air flowing through the intake tube.

They do degrade over time as any electrical component will so eventually they will have to be replaced. Cleaning them will not slow this degradation; it will only increase the period of time out of their entire service life that they, and therefore your vehicle, operate at "peak" efficiency.

There is plenty of anecdotal evidence to rule against any other than genuine Bosch MAFS. The only choices are whether to go with the Bosch part number directly related to the BMW M5 or to go with a very similar MAFS for some VW model. I have used the VW MAFS with apparent success but as to not turn this into another MAFS debate I will simply say that you will have no problem with the genuine Bosch M5 MAFS and Bimmerzone has them for an excellent price so there really no reason to get anything else.

-Josiah
Thank you for your excellent and knowledgeable input. That cleared up a lot for me.
 

·
Registered
Joined
·
138 Posts
Thank you for your excellent and knowledgeable input. That cleared up a lot for me.
My MAFs were original on my 01 with 46k on the odometer. The cleaning didn't do anything. Since it is only $6 for the cleaner, I would say it is worth a shot, but do the MAF test afterwards to confirm you are getting 130 l/hr (funny, I have just posted this same advice in another thread).
 

·
Registered
Joined
·
551 Posts
My MAFs were original on my 01 with 46k on the odometer. The cleaning didn't do anything. Since it is only $6 for the cleaner, I would say it is worth a shot, but do the MAF test afterwards to confirm you are getting 130 l/hr (funny, I have just posted this same advice in another thread).
I'm assuming a specific tool is required to test the MAF?
 

·
Registered
Joined
·
3,873 Posts
I'm assuming a specific tool is required to test the MAF?
The MAFS test is performed using the "secret menu" in the OBC cluster display. A search for "secret menu" will likely result in the procedure to perform the test.

-Josiah
 
1 - 20 of 29 Posts
Top