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DIY: M271 MAF replacement

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DIY: M271 MAF replacement

 
Old 08-20-2007, 08:51 AM
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DIY: M271 MAF replacement

Tools required:
- #20 (or 24, I forget) torx screwdriver
- 12mm socket (or get the proper torx socket, I'm cheap and this worked)
- new MAF (online purchase, $305)
- long pliers (or the proper clamp tool)
- new screw-style clamp
- long flex driver (mine was about 18" long)
- 26er of favourite rum (my father helped and he likes dark Jamaican rum)
- glasses and Pepsi (coke sucks)

Notes:
- Using the proper clamp tool makes this very easy, otherwise get an extra set of hands cause you'll need help.
- This is why replacing the pressure clamp with a screw-style clamp is suggested for future maintenance

Steps:
- Mix 2 stiff drinks
- Open hood all the way, use red button to lift to second position
- Have a drink and wonder "WTF, how does this damn thing come out"
- Remove screw on top of the front of airbox that connects it to the 90 degree bend
- Disconnect 90 degree bend and move pipe out of the way (or remove it completely)
- Locate 2 torx bolts at rear of airbox, unscrew them
- Disconnect ECU (2 connections, pull tab out then remove)
- Disconnect MAF
- Remove vacuum line at rear of airbox (push round tab in and pull up, this makes it 100% easier with it removed)
- Have a drink while trying to look for the tabs on this silly clamp buried down the rear of the engine bay.
- Curse and have another drink.
- Using long piers, reach down from beind the airbox and find the tabs on the pressure clamp. Squeeze them together and pull the clamp up and disconnect the hose, release and leave the clamp connected the the hose from the airbox.
- Have another drink and wonder "WTF? What stupid German engineer designed this, did they even think about maintenance?"
- Push airbox to rear of car. There are 2 tabs near the front that slip into rubber gromets, these need to be pushed back to slide out of the gromets and free the air box. Wiggle the airbox a lot if its stuck, typically the torx bolts fall back into the holes and prevent it from moving well, so lift the airbox slightly at the back to free these (since you cannot remove them completely from the airbox)
- Once the airbox is free, disconnect the rubber hose on it and the sensor at the front and remove from the car.
- Reward yourself for figuring out this silly German engineering, have a drink.
- Remove 3 torx screws from the rear of the airbox, separating the hose from the airbox and freeing the MAF
- Replace the MAF, reinstall the 3 screws, and remove the pressure clamp.
- Woohoo, 1/2 done, have a drink to celebrate.
- Hand-tighten a screw-style clamp on the hose from the airbox. Hand tighten only to keep it in place, too tight and the hose will not slip on.
- Reattach front sensor and rubber hose to airbox
- Slip airbox back into car, lining up hose to slip on and tabs on airbox into rubber gromets. This is far easier with 2 people.
- Stop and have a drink, the previous step may have taken a few tries, de-stress, maybe have 2 drinks.
- Tighten screw style clamp using long flex drive, should beable to squeeze it between ECU and firewall to get at the clamp
- Tighten torx bolts at rear of air-box
- Reattach 90 degree bend and torx screw
- Reinstall vacuum line
- Connect MAF and ECU
- Close hood
- You're done, have a drink!

Shop time on this is 90 mins, can be done in 30 mins if you know what you're doing and have a set of hands to help.
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Old 08-20-2007, 09:43 AM
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thanks for the write up....any pics?
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Old 08-20-2007, 04:33 PM
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Very good DIY. This has been added to the sticky thread.
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Old 08-20-2007, 04:39 PM
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Awesome!!!! A fellow drinker!!!!

You rule!

I always mix and mech. But I'm a Gin guy.

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Old 08-21-2007, 08:05 AM
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Originally Posted by drexappeal View Post
Very good DIY. This has been added to the sticky thread.
Add the O2 sensor replacement DIY too, it took a bit of effort to hunt down where the connector is. Since these are maintenance items some will want to replace them too.

Thanks Drex
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Old 08-21-2007, 08:23 AM
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Some pics I borrowed from the other thread.

Note: you do not need to open the airbox as shown in the pics.
Attached Thumbnails DIY: M271 MAF replacement-2007_0422maf0001.jpg   DIY: M271 MAF replacement-2007_0422maf0004.jpg  
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Old 08-21-2007, 12:37 PM
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I will gladly add some pics I took a while back, with your permission scotty (your thread, so thought I'd ask first). I took them to write up a DIY like this, but haven't found the time. Say the word and I will make it so.
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Old 08-21-2007, 12:44 PM
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Originally Posted by mtnman82 View Post
I will gladly add some pics I took a while back, with your permission scotty (your thread, so thought I'd ask first). I took them to write up a DIY like this, but haven't found the time. Say the word and I will make it so.
Word.

Anything to help the community out. I have kept my C230 past warranty, so the more DIY threads for maintenance items, the better!
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Old 08-21-2007, 10:53 PM
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1st pic is engine bay open.

Next 2 are for disconnecting the battery. I disconnected the battery and stuffed the cabin air intake with a rag:

Last 2 are a couple more pics of that tough bolt (only tough because of the 'tube' you have to go thru to get to it:
Attached Thumbnails DIY: M271 MAF replacement-enginebay.jpg   DIY: M271 MAF replacement-battcov.jpg   DIY: M271 MAF replacement-battuncov.jpg   DIY: M271 MAF replacement-toughbolt1.jpg   DIY: M271 MAF replacement-toughbolt2.jpg  


Last edited by mtnman82; 08-21-2007 at 10:56 PM.
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Old 08-21-2007, 11:03 PM
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Next is removing the air guide pipe from the airbox.

Then another pic of the MAF plug, vacuum line, and other connecter that all need to be unplugged. The 'other' connector needs to be removed from the MAF tube.

Then 3 pics of the computer connectors. 1st is plugged in. 2nd shows the tab pulled - pulling the tab disconnects the connector, very nice. 3rd shows both computer connectors unlugged.
Attached Thumbnails DIY: M271 MAF replacement-airguidepipe.jpg   DIY: M271 MAF replacement-mafvacotherplugs.jpg   DIY: M271 MAF replacement-compconn.jpg   DIY: M271 MAF replacement-compconnpull.jpg   DIY: M271 MAF replacement-compunplug.jpg  

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Old 08-21-2007, 11:22 PM
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oops, forgot one of the MAF connector & vacuum line disconnected and other connector removed from the air pipe.

Altitude sensor disconnected.

The nasty hose clamp - I had all ready replaced with a screw type clamp when I took the pic.

After lifting the rear of the airbox while pushing on the front of the airbox towards the rear of the car, the airbox will come free. I couldn't remove the crankcase vent hose on top of the engine, so I took it off on the air pipe when I had the airbox out - it's a bit of a pain to do it this way.

Final pic shows the mounts the tabs on the front of the airbox slide into.
Attached Thumbnails DIY: M271 MAF replacement-mafvacotherunplugged.jpg   DIY: M271 MAF replacement-alt-sensor.jpg   DIY: M271 MAF replacement-badclamp.jpg   DIY: M271 MAF replacement-lasthose.jpg   DIY: M271 MAF replacement-mounts.jpg  

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Old 08-21-2007, 11:30 PM
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Next pic is the airbox assy sitting on the bench.

Then a pic of the open airbox. You don't actually have to open the airbox, but I took the opportunity to clean the sand/debris out while it was easy to do so.

Next a pic of the 3 screws holding the MAF to the airbox. Note another 'tube' you have to go through. I'm sure Mercedes has a special tool they will sell you for this .....

Next is a pic of the MAF assy separated from the airbox.

And last is a pic of the MAF separated from the pipe. The MAF just pops off, but it is secured/sealed with a rubber o-ring.
Attached Thumbnails DIY: M271 MAF replacement-onbench.jpg   DIY: M271 MAF replacement-openairbox.jpg   DIY: M271 MAF replacement-mafscrews.jpg   DIY: M271 MAF replacement-mafoff.jpg   DIY: M271 MAF replacement-mafout.jpg  


Last edited by mtnman82; 08-22-2007 at 03:39 PM. Reason: spelling (D'op!)
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Old 08-22-2007, 03:48 AM
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Nice Write Up! THANKS!
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Old 07-07-2010, 02:42 PM
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very nice writeup. I started drinking and attempting to do this last night but realized waiting a day and actually finding out what crazy steps are involved would be a good idea.

on my jeep its a hose clamp, 3 torx, and the maf plug, can't even get a drink in. this is a tad more involved, still doesn't look bad though. pics helped a lot
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Old 07-07-2010, 02:44 PM
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didn't see the date, I apologize for diggin up an old thread and not adding anything to it. really is helpfull though
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Old 07-07-2010, 09:20 PM
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Originally Posted by scottyballz View Post
Some pics I borrowed from the other thread.

Note: you do not need to open the airbox as shown in the pics.
on the 2nd picture where it says torx bolt, you may use a 6-pt 8mm socket, i have the e10 torx tool but it wont fit due to the pipe surrounding the access to the bolt.
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Old 07-20-2010, 06:40 AM
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i used the 6pt 8mm on that bolt. I just removed the MAF, cleaned it with the CRC spray, reinstalled, cleared the code with my scan tool and the light hasn't come back yet. Its been 2 weeks. I don't know how long it will last but I'll keep you all posted. Figgured the spray was worth a chance before I spent the big bucks

CRC recomends cleaning the MAF everytime you change the air filter, (which apparently my MB dealer doesn't do anyway or think i'll find out if they dont change the filter) but of course they would suggest that since its their spray.

all i know is cleaning it has worked for now and well see how much longer i can run this MAF, my car is at 102k miles now
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Old 07-20-2010, 01:27 PM
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Just throw away the MAF and go with speed density lol jk.
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Old 12-15-2010, 12:08 PM
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Thanks for the write up. Do you have to completely remove the airbox to install the MAF? Or can it be removed with the airbox still in place? I know the space behind the MAF is tight.
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Old 02-03-2011, 06:46 AM
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To clean the MAF, can I just open the air box and spray the cleaner in it or do I need to remove the entire airbox from the car and take it apart like in the pics above?
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Old 02-03-2011, 07:08 AM
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How does the car respond now?
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Old 02-03-2011, 06:47 PM
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I'm stuck in the garage and am having a hard time removing the box. I've followed all the instructions and disconnected everything except for the rear hose that goes downwards. The airbox cannot be removed w/o first unclamping this hose b/c I can't pull the airbox up from the rear high enough to get the stupid thing out.

What tips do you guys have on removing the pressure clamp? Car can't be driven until I complete this. Please help. Thanks.
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Old 02-03-2011, 10:35 PM
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Yea, that hose clamp is a biatch. I think I used a smaller screwdriver to pop it apart - it was not easy. Make sure you don't poke a hole in the hose. Replace that clamp with a 'normal' type hose clamp when you re-assemble and life will be a lot easier.
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Old 02-04-2011, 01:55 AM
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Originally Posted by mtnman82 View Post
Yea, that hose clamp is a biatch. I think I used a smaller screwdriver to pop it apart - it was not easy. Make sure you don't poke a hole in the hose. Replace that clamp with a 'normal' type hose clamp when you re-assemble and life will be a lot easier.
Wow, an answer from the man himself! Thanks. So do I just poke at the clamp to remove it or pull it off from the strap itself? Did you have to break it when you removed it?

I tried squeezing the pressure clamp with pliers like you recommended at first and it just bends the tabs. No release.
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Old 02-04-2011, 04:36 PM
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I've never cussed so much in my @#[email protected]# life. My finger's hurt, hands are dirty and man that was a pain in the ****. I'm never doing that ever again! This isn't a DIY for the faint of heart. Once I finally got the pressure hose clamp off, I couldn't even pull it apart with my hands! It's one strong piece of steel.

Just a little reminder for anyone who even thinks about attempting to do this. It's an all or nothing job. If you get the hose clamp half way off, you won't be able to put it back to normal nor will you be able to drive the car. You'll have to go all the way or have that @$# towed to your Mercedes shop.

Only do this if you have the proper equipment, can get a bit creative, don't mind ripping [email protected]#$ apart, can leave your car out of commission for a couple days and don't mind hating Mercedes and swearing to never buy another one.

Lexus here I come.

Since this thread has helped me so much, I thought I'd load up some photos and put in a few words of my own for anyone who dares to try this DIY MAF cleaning/replacement.

PHOTO 1: All the tools I used. The circular part of the wrench was used to grab a hold of the tab on the hose clamp. I pulled the @#$# out of it pulling it as hard as I could.

PHOTO 2: I don't think anyone's ever loaded a pic of the actual MAF. Here it is. I sprayed both metal components using the CRC MAF cleaner spray.

PHOTO 3: The air box taken apart. Three torx screws as mentioned holds the three pieces together. You have to yank it pretty hard to pull it apart once the screws are removed. Careful not to drop your $800 MAF when you're doing this.

PHOTO 4: This is the @#[email protected] that was giving me such a hard time. Even with the box removed from the car, pulling this off was still very difficult! It's on tight. I can't see how there's any way to remove it w/just a pair of pliers. I had to beat it off.

TECHNIQUE:
A few things I learned from doing this MAF removal.
- The "tabs" used to secure the two sockets to the ECU are not really tabs. There are handles on opposite ends. They pull apart away from the center (forward/back) parallel to the ground. It "slides" out. It's not hard to do. You just have to figure out the mechanism.
- I wasn't able to remove the hose clamp w/pliers. I don't see how that's even possible unless you're Superman w/tiny hands. I placed a long flat head screwdriver in between the clamp and hose. Using the hammer, I slammed the screw driver in between and pulled up moving the @#$# out of it. I then took the circular part of the wrench and pulled on the tab as hard as I could. This literally took 45 minutes or longer.
- Notice I tied a wire to the wrench. I tied any and all tools I used to this wire so I could fish it out in case I dropped it into the engine bay, which I did. Good thing I had the wire! Use string if you have it. It's much easier. I just used wire b/c I didn't have string on hand.
- The socket used to loosen the two rear torx screws was a 5/16" socket. You'll need that extension to get access.
- I never unplugged the battery.
- To remove the vacuum hose, pinch the circular tab/bracket like you're pinching a nipple. Pinch in the direction perpendicular to the length of the car.
- For anyone who cares, the part number for the MAF is A 271 094 02 48. I've seen non-ebay ones priced from $288 - $800.
Attached Thumbnails DIY: M271 MAF replacement-0204011720.jpg   DIY: M271 MAF replacement-0204011359.jpg   DIY: M271 MAF replacement-0204011358.jpg   DIY: M271 MAF replacement-0204011323b.jpg  

Last edited by casper_c230; 02-04-2011 at 09:44 PM.
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