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How To Replace MAF (w203)

mobeyone

MB Enthusiast
Joined
Apr 23, 2005
Messages
1,432
Car
E280 S211
Finally got round to doing it - hope people can benefit from it and save some $$.

Admin - was not sure how to post in the correct section..

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Basic overview of the engine - the MAF is loacated at the center of the rear of the engine not viewable at the moment.
To the front of the airbox, remove the front part, take care as this is held on with rather flimsy plastic clips.
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Once the front part of the airbox has been removed, you will see a small rubber mounting - the airbox sits on 4 of these, carefully pull up one corner at a time to release the airbox. Note the air intakes at each of the front end, once you have lifted the airbox, these will slip off.

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MAF - This is the MAF. You will see that the MAf sits on top of an air intake and is held firmly in place by a plastic housing to its center.

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Remove the plug to the right by pressing both sides firmly until released. Then
prise the plastic housing which looks like an M shape to the front of the housing until free and then push back the metal clip at the rear which you can see below. Then slowly loosen until the MAF comes out - but take care and do not use much force.

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Once the MAF is removed, you should see the rear of the air intake and a rubber band may be left here, lift this out (if not already on the MAF) and attached to the new MAF ensuring you line the band up with the markings on the air intake at the rear of the car.

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Ensure the lines are matched up on the rubber band - these will sit the MAF firmly in place and ensure you have attached the plastic housing to the top of the MAF. This is removed with a small amount of force by undoing the clip at the front.

Then replace, push in firmly and ensure the MAF sits snug in the center, reconnect the plug and replace the airbox following the above.

Replace the airbox making sure the box sits firmly ontop of all 4 mountings and attach the air intakes.

Finally, replace the front cover again taking care you do not damage any of the clips like i did!

Hope this is of use.

mobe
 
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I'm no expect but I was under the impression one is supposed to perform the MAF replacement together with a recalibration of the ECU as it re-learns the new component etc. Can anyone confirm this? I was looking at replacing mine as well but held back to get to a proper mech that can also do the ECU reading./reset bit. Anyone helP?
 
KLee said:
I'm no expect but I was under the impression one is supposed to perform the MAF replacement together with a recalibration of the ECU as it re-learns the new component etc. Can anyone confirm this? I was looking at replacing mine as well but held back to get to a proper mech that can also do the ECU reading./reset bit. Anyone helP?
The ECU will get used to the new MAS over time anyway, just as it does with changes in fuel quality.
 
KLee said:
I'm no expect but I was under the impression one is supposed to perform the MAF replacement together with a recalibration of the ECU as it re-learns the new component etc. Can anyone confirm this? I was looking at replacing mine as well but held back to get to a proper mech that can also do the ECU reading./reset bit. Anyone helP?

Shude is right as it has an adapative memory but I agree as mine still hesitates a little and I think a clean reset will cure this which should happen this week so will let you know.
 
Just got back from my visit to Steve at SPR autos.

Wired my motor and we coudl not find ANY fault codes relating to a misfire, mixture!

But - I had lots of stored faults none of which made sense but there was anything between 10 and 20 in there including one relating to: crankshaft sensor (P90033 I think) which he said is also a very common problem with the 203.

Steve kindly reset everything stored, restarted and no faults.

My car is now running mega smooth, quick acceletation etc.

We both chatted on why this misfire could be happning and we both agreed that due to the number of faults, it (ECU) may just be too confused and cause or have an adverse reaction to the car.

So, my advice is a full reset of the ECU is a must when attempting to cure any symptoms relating to the above.

Fully recommend Steve at SPR - top bloke and very knowlegable.
 
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