Where are they on a 99 230? Is carb cleaner ok to clean them? I am hoping that cleaning these will fix my intermittant cold start problem.

 

Chances are it's going to be under your air filter housing - here's a link for the cleaning of the MAF it's for a BMW, the MB MAF is identical though. MAF FILTER CLEANING LINK

 

Frank,has anyone CONFIRMED that this has WORKED for our cars ?

 

The link looks interesting. Be aware though, Vaseline will damage rubber over time. I would not recommend it at all!!!!!!

 

Really , I've been using it on the O-rings on my pool filter for years with no problems.

 

The MAFS is located on the right side down low on the large black hose.
It has a large connector attached to it.

The O2 sensors, there are two they are located on the exhaust pipe before the cats.

The MAFS can be cleaned. You should go buy the 2001 MAFS connector pipe and relocate it to the upper position to eliminate the low end hesitation.

If the car has a rough idle at start up try using 89 octane gas it will fix the problem without any noticeable loss in performance. It will not hurt the engine to use 89 octane.

Want more power? Get Linh's pulley kit, it kicks *** and you will burn the rear tires right off in no time.

The link posted above is partially correct, it is not under the filter housing and it is correctly called a Mass Air Flow Sensor or MAFS for short.

 

Use Brake cleaner NOT carby cleaner.
Brake cleaner will drip dirt off and completely evaporate.
Some carby cleaners are too strong in the solvent side.
I just wipe a smear of engine oil on the o ring, on 1998 230slk it is in the ally bit where the MAF pushes in.

bazzle

 

Just wanted to chime in about cleaning the MAF. I would not recommend using brake cleaner OR carb cleaner on the MAF. These chemicals are not deemed "plastic safe" and you could be corroding the plastic housing in addition to "cleaning" the hot wires, etc.

I used a product called "CRC Mass Air Flow Sensor Cleaner" which is supposed to be safe on all plastics and does an excellent job of cleaning the sensitive wires/plates on the MAF. It was about 6 bucks at the local auto parts store (Schuck's, in my case)

After cleaning, I noticed an immediate improvement. I bought my '99 E320 about 6 months ago and I thought it drove fine, because I had nothing to compare it to. My CEL came on with the code P0173 "Fuel Trim Malfunction - Bank 2" about a month ago and my idle felt a bit rough, so I decided to try and clean the MAF before spending the $$$ to replace it.

Wow! The acceleration is WAY better than it has ever been since I've owned the car! The idle is smooth as silk. 'Tis wild how such a tiny little wire makes such a huge difference.

Hope this helps somebody!

 

Nice info. CRC is a great company, I used to be a distributor for their products.Great to know.

 

There you go... a decicated cleaner. Do not wipe with a cotton tip as sensors have been reported damaged, spray only.
Brake clean has been used for years, carbi clean can damage plastic.

Bazzle

 

...so after cleaning the sensor with the crc..how would i clear the code of the check engine light.. would i have to remove the battery? i heard that if you remove the battery you will need a code to start the car back on..is that true?

 

Remove the negative terminal of the battery, and leave it off for at least 30 minutes, that should clear the codes. Have your radio code handy as you'll need it to get the radio working again. The car should start normally with no additional codes or problems.

 

Can you really clean an o2 sensor, one that's got caked on carbon buildup? Also, Squishy is wrong, all cars with cats have a pre and post cat sensor. When the code is for sensor 1, bank 1 it means pre-cat and drivers side (on V6 or V8), bank 2 is passenger side, sensor 2 is post-cat.

As for resetting codes, if you know the code then you probably have access to an obd2 scanner and that will reset codes. They are available pretty cheap these days, ebay or pep boys (had them for well under $100).

 

I have cleaned my MAF sensor on my 99 SLK on 2 occassions. My brother, who is a mechanic, recommends using "contact cleaner" electronic parts. Just spray it on and let it drip dry. It has worked great with no problems.

I would not recommend using vasoline as an o-ring lubricant, it will break down the rubber. I prefer a solicone based lubricant.

Good luck!!

 

I took my car (2001 E320 57,400 miles) to dealer for CEL they told me I need Air Mass Flow Sensor replaced quoting a $750 bill. I declined to replace it after reading on in this messageboard. They charged me $109 for the diagonose.
I am planning on cleaning MAF this weekend with "CRC Air Mass Flow Sensor Cleaner", I also ordered a ODBII from www.autotap.com for $200 so I don't take my car to dealer again for small jobs like this. If cleaning does not work I will buy Mercedes brand MAF for $440 from the dealer and still save money.

I will take photos of this job and post them for next guy who wants do this yourself. Let me know if you guys suggestions e.g. if I need to change spark plugs etc.?

 

I bought the MAS cleaner a week ago planing on doing this job.

Is the sensor on my '05 E500 at the back of the air intake in the plastic intake tube?

Does the sensor have to be removed or can it be sprayed in place?

Are there any other sensors I could clean at the same time?

This forum is a great help.
Thanks

 

I'm not familiar with the W211 but it has to be somewhere after the airfilter and before the throttle body and that can't be a long run on that car. There maybe two MAF sensors on the V8's, specially if you see two air filters. There's a goldish wire, usually about 1/2" long that is the actual sensor wire that needs cleaning. If you can access that without taking anything apart, you are good. It's also good to clean the entire inside of the sensor housing as you don't want dirt to redeposit itself on the wire again.

 

You can try cleaning but it failed for me this weekend. I opened the sensor and cleaned it, placed it back in and does NOT work. It is in worst shape than before I cleaned it so I left my car in garage and will place an order for a new one tomorrow until then I am without a car.

If you still want to try cleaning it here is some photos I took while doing the job. My suggestion, if your car drives ok and afraid of having no car for few days than don't try cleaning it instead buy one and keep it on the side just in case cleaning fails (if it doesn't fail and works make sure you can return your new MAS back). Hope this helps!
http://img407.imageshack.us/my.php?image=img1063xj6.jpg
http://img407.imageshack.us/my.php?image=img1064jd1.jpg
http://img266.imageshack.us/my.php?image=img1065gh7.jpg
http://img266.imageshack.us/my.php?image=img1069xi1.jpg

 

It appears that you are cleaning it wrong from the pictures. First, remove the MAF sensor from that tube you are holding in your hand. Usually Bosch/Siemens uses security torx screws (torx with an annoying pin in the center) to hold the sensor to the tube. Then clean the tip of the sensor (bottom of sensors in picture below) with a good blast of CRC MAF Sensor cleaner from all angles.

 

Remove sensor screws using sec torx or pliers. (you can use standard self tappers to replace)
Spray liberally into the chamber of the sensor.
Shake dry.

Bazzle

 

Thanks guys... looks like I screwed up. Now the sensor is definetely bad b/c my car RPM goes up and down. When I stepped on gas the check engine light started to blink so I did not even bother to drive just left it in the garage. I just ordered a new sensor online from http://www.alloemautoparts.com/ for $273.99 (free shipping) I ordered from them before they are great, if you do call them talk to "Ria", she's nice to work with.

They even have Mercedes brand for $364 but she said it's the same thing with different packaging.

Guys should I even try again taking apart and clean it or it's obvious that I killed it?

 

No, you didn't kill it, just probably caused dirt to sprayed on it by spraying the wrong part. Disconnect the MAF if it's causing problems, it will run fine without it. Also, clean it, get it working and then keep the spare for later use or return it.

 

I did not take the sensor out of the housing b/c I did not have a screw driver for it but I did spray on sensor.

I disagree that car will run fine without sensor. Yes, car runs BUT without stable rpm and will smell unburned/unused gas b/c you are not getting correct gas flow. I would not recommand anyone driving with sensor disconnected, you may face bigger problem if you do. Thanks!

 

That's what you need to know. Trust me, I've run my perfectly running MB with the MAF sensor disconnected just for fun, most people wouldn't know the difference. If your motor is surging, unstable RPM, then your problem is not the MAF and you most likely have a vacuum leak. If that's the case, a shiny new MAF sensor would not do the trick but at least you'll have a spare.

 

I somewhat agree with b/c my old 1994 E320 worked almost fine with MAF disconnected but I do not think anyone will recommand doing that b/c you'll abusing your car engine. Anyway, I did not have unstable RPM issue prior to cleanning MAF sensor in my 2001 E320 so I know for sure it is sensor related. My MAF sensor has arrived today can't wait to go home and install it. I will take your advise and try to clean my old sensor again.