MAF Sensor

[Alex]

I just wanted to start this thread, cause I'm verry interested in your experiences with your MAF sensors. How often it has broke, if cleaning has solved the problem an so on...
My experience:
'only' one MAF blown, in last 12 months The reason was a to much oil at the filter ( I supect) and it was dead (VAG error message ASR light on...) so no chance with cleaning.

 

[marriedblonde]

Hiya Alex
I've thought I have had MAf problems in the past but I was recommended to do some logs with the vag com on it and it all seemed ok until recentley when I have started to get an intermitant error reported....
Guess when it's in for the new airbags and seat frame they will sort it out then.
Marriedblonde

 

[MikeM]

Hi Alex,
MAF issues are a large feature in the USA over on Tdiclub.com, The BA Passat hot wire type seems more robust than the later ones and one has to be so very carefull in doing this at all.Apart from the deep suspcion that VW has been using poor quality components in the post 96-7 MAFs, they are so easily damaged by oil from overfilled engines, oil being sucked off aftermarket high performance airfilters (I've takeen my K&N filter off for that reason & gone back to stock paper filtering but twice as frequently as standard), airborn/aerosol spray involving silicones etc., etc.
Also, need to choose your chemical cleaner with some care.
Good luck reading up on this!
Mike
Exeter, UK
[hah-hah ... I can now fly direct to Graz from Stansted fairly cheaply, so beware!]

 

[Turbo Bora]

Alex,
I just lost my MAF on my 2001.5 TDI Jetta. I have used both the Cone and the panel filter, but on my 2001 TDI (with no problems)It is doing fine. Both cars have the same mods:
UPsolute chip
Cone and Panel ( I change back and forth).
Epsilonian Device
CCV bypass
So far no probelms with the 2001 Jetta, but the 2001.5 has had an ABS pump module replaced ( by the dealer)and a bad MAF.
I noticed the 2,500 RPM Lag and hooked up the Vag-Com to find the MAF error. Later that day I carefully cleaned the MAF with Denatured Alchol and reinstalled it. The MAF was still gone and I will now donate it to science. Contact me if your the mad scientist that wants to experiment on the late MAF. I won't give it up until I get another from Danix (TDICLUB.COM) (is fred's server back up yet?)
I think the VW MAFs in the later models are weak. I am not going to sit around and bitch at someone because I know that there is going to be a way around this soon. The
thing to do is to find a way to either bypass the MAF signals or to use a MAF made to fit what our ECU wants to see without the sensitivity of this weaker one being used by VW.
I guess I am trying to say that we should continue to work this one out by trial and error. I know this is not that hard.
[ 22 March 2002: Message edited by: Hallopt45 ]

 

[Turbo Bora]

I have preformed a internal inspection on the Old MAF. Talk about micro!! My conclusion is that someone will have to redisign the MAF circuitry completely. Since this stuff is so tiny I will be forced to take it to a friend of mine. At this point I am thinking that it would not be an easy endevor. By looking at the circuit board there seems to be a micro processor on the board that translates Velocity pressure to ECU logic. The entire thing looks very fragile sealed under a protective coating that is clear. I can't help wonder if there is a way to implant a tiny fuse on the board to keep it from self-destruction.
On the outside of the Sensor (black) there are two prongs and a symbol for a diode or resistor. The letter 'K'is noted. I wonder if this is a test circuit, or a bypass.
Any ideas?

 

[Sudz]

Originally posted by Alex:
I just wanted to start this thread, cause I'm verry interested in your experiences with your MAF sensors. How often it has broke, if cleaning has solved the problem an so on...
My experience:
'only' one MAF blown, in last 12 months The reason was a to much oil at the filter ( I supect) and it was dead (VAG error message ASR light on...) so no chance with cleaning.

Ditto...made the same mistake. Now I have to schedule an appt. with the dealer to replace it.

 

[Turbo Bora]

Ok, now I know that the sensor film inside the maf is what is getting hit. This must cause the failure.
How about replacing the metal film? I know this would be a pain, but 175 for a Maf is a pain too.
Of course just conecting the circuit board to the film looks like an impossible task, but then again I am on a mission. Please post with any ideas...

 

[Alex]

I guess I need to jump on to this mission. I will try to open my defective MAF also. Do you mean the metal film that can be seen without opening the MAF? By the way, I have an E at the resistor prongs???
I guess the metal plate does measure the amount of air, by pressure. I mean if there is more Air-flow, more Air is pressed through the little hole and more pressure is made to the metal plate, I guess I need to open the MAF to find out how the metal plate measures the pressure. Or am I completely wrong?
...alex

 

[René]

It is measuring temperature changes and determining the current required to maintain temperature. THe key failure point is the tiny lead attachments at the sensor base to the electronics, they would have been better served to have potted the MAF in a hard compound instead of the soft silicone that they did. It is way to fragile for automotive use.

 

[Turbo Bora]

This looks like a real humm dinger... I guess we might take a good MAF and using grounding methods remove the silicone soft stuff and use a more hardy, sturdy compound.
While we are in there it might do well to increase the size of the conections (the tiny ones) and see if this makes it last.
This stuff is so tiny that I will need some of my buddies equipment to even look at them...
I continue into the micro-mission even futher. Any more ideas while I am there?

 

[Turbo Bora]

Originally posted by Alex:
Do you mean the metal film that can be seen without opening the MAF? By the way, I have an E at the resistor prongs???
Alex,
The metal plate is part of it, but the real problem I will have to agree with Valois here is the tiny conections closest to the collecting end of the sensor, and how they are attached to the circuit board.
The other part may also be that the silicone holding all of it in place is too soft and allows to much movement under vibration. I have seen other stablizing gels that are harder to the touch, but the size of the conections to the circuit board are an issue with me as well. If we try to remove the silicone gel the connections will surely be destroyed. Valois, is there a way of using chemical solvent or heat to remove this gel?
Alex, as far as I can tell the "E" and symbols printed on the back with the two prongs are for factory testing the MAF. Mine is a "K". We should note all the ones we work on to see if there is a trend. I truly think this is a classic *&%%^ up on VW's behalf.
[ 09 April 2002: Message edited by: Hallopt45 ]

 

[Alex]

I will have to open one to know what I'm talking about
...alex

 

[Juuso]

Hello guys. I was reading this maf discussion, and it seems to be quite unknown matter to most of us, so i decided to register and try to help you .
The hotfilm consists 3 major parts. Heated filmresistor and two NTC temperature resistors. This type of MAF measures mass of air sucked thru it by measuring how much current is needed to keep hotfilm resistor at 160 degrees celsius above inlet air temperature.
The Second measured value is inlet air temperature which greatly affects to airs mass/volume ratio, which is measured by one NTC filmresistor.
The second NTC resistor is for measuring the hotfilm temperature that it is always 160 degrees above inlet air temperature. (this works with most newer 5-pole Bosch MAF).
Some older MAF that used hotwire instead of hotfilm sometimes had "afterburn" function that raised the temperature of the hotwire several hunded degrees for few seconds after engine stopped to burn of any debris etc (that seems to be one reason why older MAFs worked longer).
One possible way to prevent MAF damage and possibly slightly increase performance is to install very fine "steelnet" to MAFs "mouth" and attach electric wire from the net to ground(chassis or engine). This procedure prevents negatively charged particles in inducted air to impact with the hotwire(film) that may cause voltagepeaks (very, very small) to affect the feedback signal from MAF to ECU.
One good way to clean MAFS is to spray carburettor cleaner spray from engine side thru MAF.
I hope this helps you to get even more fussed, but this is all that came to mind at this moment.If you have any questions please don't hesitate to ask, I try to find proper info if needed.
MAY THE FORCE BE WITH YOU

 

[Juuso]

Back again..(very good memory, but very short)
There is one good first symptom of failing MAF. If engine performs well at small gears, but lacks power at high gears or/and at heavy accelerations, but no faulcodes are showing means usually too lean fuel/air mixture. this sometimes appears as lambda sensor faultcode,instead of MAF failure.
the reason why, is that when MAF's hotfolm/hotwire gets dirty/minor damage, the hotfilm doesn't cool as much as it should be.
This affects to ECU determine sucked airmass too small and gives shorter pulses to fuel injectors (less fuel to real airmass).
This is very usual problem with just chipped cars that worked fine before chipping, but after chipping starts loosing maximum power.
99% of problems have been car related, not chip related.especially with these famous VAG products.

null

 

[mwragg]

I have just bought a UK-spec Golf TDI 130 PD and I am going to have an UPsolute chip fitted in 2003.
Is there a problem with the MAF sensor on this vehicle and, if so, how often should I check/clean/replace it?

 

[Alex]

The problem with the MAF can occure at all the TDI/1.8T models. So it can also occure at yours, but it does not mean that it will happen in your car