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-   -   MAF Sensor Removal & Cleaning (https://mbworld.org/forums/e-class-w212/677323-maf-sensor-removal-cleaning.html)

Mud 08-09-2017 06:55 PM

MAF Sensor Removal & Cleaning
 
I thought I would post up some info on how to pull the MAF sensor if needed. I found that you don't need to remove it from the engine to clean it using something like CRC MAF sensor cleaning spray (non-contact, evaporating), but I since I was removing it to get to the throttle body, maybe this is interesting info. All in all, a somewhat fiddly operation.

First up, I was also replacing the air filters. I've used Pentius filters forever on a variety of vehicles. Nicely made, perfect fit and I think they ran under $6 each at Rockauto.
https://cimg4.ibsrv.net/gimg/www.mbw...40b3a036d6.jpg

https://cimg7.ibsrv.net/gimg/www.mbw...2a0b20454b.jpg


Upon removal of the air filter housing, this is what lurks at the back - this is the MAF sensor housing. It's latched into place with 2 arms. You spread the arms slightly and tilt it out of the inlet housing that it sits into.
https://cimg9.ibsrv.net/gimg/www.mbw...0b472fbe1e.jpg


Here it is out of the engine, you can see the 2 arms. They latch into a small bracket on the intake, but the worry is that if you are too energetic or the plastic is brittle after years of heat-cycles, you can snap an arm.
So be forewarned to be careful, the housing and sensor have to be bought together. Thank you MB. You can also see the MAF sensor under the protective screen.
https://cimg1.ibsrv.net/gimg/www.mbw...c2b8415407.jpg


The connector can be tricky. I used a mirror to give you a view of the connector latch. That light gray part is pushed in while the connector is pulled from the sensor. I had to use a small pick to get it pushed in enough to clear a small retaining tang.
https://cimg2.ibsrv.net/gimg/www.mbw...d4b2fcfbec.jpg


I also pulled a small vacuum harness retainer out of the way to reach the MAF connector. The screwdriver is used to slightly spring the retainer back from the manifold, it's then just pulled up.
https://cimg5.ibsrv.net/gimg/www.mbw...bceb9d43e7.jpg


Anytime you ever open up an intake, use a rag to block the opening. It's a rule of physics that items can move clear across the garage and fall into the opening.
https://cimg8.ibsrv.net/gimg/www.mbw...c8f930e429.jpg


Here's what all the fuss is about - you can see the heated wire/resistor under the screen. Never touch it or use a q-tip to clean, just spray it with specific sensor cleaning spray. At 50k miles I could see a difference in the before and after cleanliness of the wire.
https://cimg1.ibsrv.net/gimg/www.mbw...6e3b484832.jpg


As mentioned, if you look at the installed MAF, it can be spray cleaned as it sits in the engine. I suggest doing this as you change air filters or about every 40-50K miles unless you live on the end of a dusty road in east Texas. The spray will evaporate and if there is a drop or two in the intake, it will burn off immediately.

KEY08 08-09-2017 08:58 PM

that is a fantastic write up!

Mud 08-10-2017 08:18 AM

Thanks, I appreciate that. I mulled over a couple other things since posting:

Meant to mention that the MAF sensor sits into a silicone ring fitted into an elbow that in turn attaches to the throttle body. This ring can be easily popped out and wiped clean.

I think the TB on the 3.5 is positioned poorly in terms of heat soak, down low and in the back of the engine. "Most" vehicles have it either on top or front of the engine where it at least gets some airflow from vehicle movement and/or fans. So on this engine, there may be a tendency to cook fuel on surfaces and increase deposits. May need more frequent cleaning and I could see the TPS sensor possibly failing earlier due to heat. All conjecture on my part though just take it as idle thoughts ;)

thefisch 08-10-2017 02:16 PM

Thanks for sharing and pointing out the 'clean in place' option. Much easier and within my skill set.


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