brokenstunter

Does any body know why the MAF sensor's are prone to breakdown on these cars? I mean, they are on hundreds/thousands of different makes/models with less prestige and theirs last MUCH longer.
It is also a Bosch, so does fault go to them or was it designed at Benz and given to Bosch to build?
There just has to be a solution to this problem, am I wrong?

Bo CL500

i had to replace mine at about 38,000 miles

ohlord

you cleaned it? CRC brand maf cleaner.
what codes did you pull that led you to believe it had failed?
When did you last change your fuel filter?air filter not k/n
Have you checked for leaks in the intake system?
They don't fail that often.
If it did only $200 to replace.
Post the codes.

Air Marshall Eldritch

Do what Ohlord says, but in the meantime, here is why they fail:

MB buys Bosch MAFs that are manufactured to very specific tolerances. This is also true of O2 sensors. The Bosch assembly line has one for MB and one for everyone else (I'm generalizing a little here). It is somewhat like the infamous $900 hammers the army used to buy in the 1980's. Part of that price was procurement fraud and part was that the US Army demanded a hammer be 99.999% within exact size/weight. Could you smack a nail with a hammer that is 99.9% within spec? Of course. But the machining required for the higher spec is custom and so costs a lot extra.

MB spec sensors are like Army hammers. A regular Bosch MAF will do just fine in a Toyota or BMW, but the MB computer will not accept that range of values that are ok for other manufacturer computer chips.

~CL500~

+2 on Ohlord's post. It's best to clean first as you may have a good sensor that's just dirty. In my case, the sensor was bad.

RBrenton,
Nice post! I had no idea and always thought they were the same. I bought an OEM MAF so I feel better now.

brokenstunter

I did the clean with CRC cleaner, reset codes and within 10min of driving the car did a slight stumble upon acceleration and idle.
I then read on a post on this forum that if you disconnect the MAF the car wouldnt stumble upon acceleration or idle. I disconnected the MAF and no stumble. I decided to order new from my dealer at cost plus 10%. The total bill in CDN funds was $413.00.
I put in new sensor and reset codes and voila! No more ceck engine light. I will post the codes asap as I cant rember and Im not home for a couple days.
I geuss the tighter values on the Benz computers makes sense. Just wish it was longer lasting I guess. My car has 36,000 miles on it. Seems like an early failure to me.

MB Fanatic

How often do you replace the air filter? Are you using something like a K&N air filter?

brokenstunter

Im only using stock filters and parts on the car. Its my cruiser so no need for speed. I change em bout every 10,000km.
That is two maf's since new, am i doin something wrong?

ohlord

you clean the mass air sensor by taking the sensor out of the maf body to clean it?
are you using fuel with a high ethanol %?
If you cleaned it in place,the stumble may have been from unevaporated maf cleaner.
Dealer part should have a warranty.
2 in 36k is unusual,fire off a letter to mb of Canada certified post and see what response you get.Worth a try.Tell them what you paid,and you might have to consider another make next time

brokenstunter

Its funny you mention ethanol. Because come to think of it both times it failed were shortly after using Mohawk brand gas witch is high in ethanol.
Never put 2 and 2 together because they wouldnt fail till a couple of tanks had gone through. I usually use Esso gas but these two times it was Mowhawk or bust!
When I cleand the maf I actually took the sensor out of the maf body itself and cleaned it.
So.... ethanol bad?

MB Fanatic

Too much ethanol is bad. Do you know what percentage of the fuel is ethanol? We have ethanol here in CA and our MAF's dont fail as often as yours have.

ohlord

in the ecu after several driving cycles,sort of like a short term memory so the car can go into closed loop operation quickly.The ecu gets use to the FT of brand A high test 91 octane and then you put in some 91 octane with 10% ethanol and it falls out of that very narrow range of values that the emissions system in the computer are set as ideal air /fuel ratios.You change gas back to brand A ,and sometimes it will readapt back into the narrow correct range again.I drove 1400 miles in 19 hours and not a blink of a light,got into seattle and gassed up at an arco with 10%ethanol and Bam p0170 and p0173 just like that.If I could figure out a piggy back resistor to solder on the wire and widen the range I could make a few more million bucks hopefully before the smog police got to me
A. try the fuel change
B. erase the code and readapt the ecu drive cycle.Google ohlord generic drive cycle.
C. complain nicely to the dealer where you got the Maf for 400CAN
D.Punt

sometimes guys that think if high test like 91 is required that they will get more power with racing fuel like 103 octane and it is so highly oxygenated it can also make the maf go crazy.

and you are also up at about 3500 ft. correct?So 91 octane is like 87 mixed with ethanol a sure tripper of the maf.

brokenstunter

we are at about 3500 and with that 10% ethanol it makes perfect sense that it would cause problems, man im stupid.
We can only get 91 octane up here, should i be running an octane booster? I have heard bad things about that to though.

calgary

Where did you get the security Torx tool? I am unable to remove the sensor - and therefore clean it in the maf body.
The Mohawk gasoline observation seems to be correct. Same problem here...Altitude effects have been mentioned to me by the technician at Lone Star. Nice day for a drive today in Calgary...12 Celsius..

~CL500~

Calgary,
I bought a 100 piece bit set that includes a bunch of of torx, hex and security hext bits from Harbor Freight for $9.99. You can't go wrong.

Here's the set I have:
http://www.harborfreight.com/cpi/cta...emnumber=91310

calgary

CL500: Thank you for the website. I will find out tomorrow if they will ship to Canada. That is sometimes a problem..

brokenstunter

I went and bought mine from, of all places Princess auto in the N.E..
Where in the city are u from "Calgary"

P.S, was a great day for a drive!

calgary

I tried Princess Auto also, but could only find the 6 point bit, not the 5 point. Did you find the 5 point bit???
I am in Braeside....IF you don't have the 03 CL500 brochure, let me know - I have one for you...Calgary

brokenstunter

Weird, mine were both six point torx????????????

calgary

I checked my spare MAF unit, and it requires a 5-point
security bit. How did you manage to get the 6 point bit to work????

brokenstunter

they are 5 point sorry, bad memory i guess. i did get them from princess auto though about a year ago.

hk1595

Hello every one, I have a 2003 Cl 600 that might need MAF sensor. Can someone please point out its location?