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Outstanding Contributor W221 Moderator
2010 E350 P1/P2, 2008 S550 Designo, 2002 ML320
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Discussion Starter #1
I have recently completed some major maintenance on my '95 S420 and am very happy with the results.

I changed the fuel filter, fuel pumps (got a great deal on eBay for $129/ea), fuel tank hose, delivery hose,
spark plugs, air filters, caps and rotors and O2 sensor.

The car is running very well now, but when I had the filterbox off the engine I noticed that the MAF screen was
sooty (no K&Ns, just dirty). I wiped it clean with a lint-free cloth sprayed with air intake cleaner, but am
thinking that if the screen is that dirty, the hot wire must be too.

I have read about folks cleaning the MAF with the CRC MAF cleaner or alchohol, etc. but what is not clear to me is if the MAF is removed during cleaning or just cleaned in place. Is it OK to just spray the cleaner down into the MAF?

BTW, check out the pics of my old cap/rotor. This set is from the left side and is original equipment, not bad for 144k miles!
 

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W639 Vito 110 CDI; Ponton 220S; VW Phaeton V10 tdi; 1995 S500 ex diplomatic car (gone)
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Why would you want to clean the hot wire?
 

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Yes, it's OK to clean it in place. Of course you can get it cleaner by taking it off but it's quite a bit of work to do so.
 

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Outstanding Contributor W221 Moderator
2010 E350 P1/P2, 2008 S550 Designo, 2002 ML320
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Discussion Starter #4
gartracescort said:
Why would you want to clean the hot wire?
Not sure why I wouldn't, something I'm missing?
 

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Outstanding Contributor W221 Moderator
2010 E350 P1/P2, 2008 S550 Designo, 2002 ML320
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Discussion Starter #5
deanyel said:
Yes, it's OK to clean it in place. Of course you can get it cleaner by taking it off but it's quite a bit of work to do so.
Thanks deanyel!
 

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SEC 600 V12 2dr COUPE (RHD) One of the chosen few.
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The wire does a self clean sequence when you turn the key.. It goes to high temp to burn off anything that may be on it. The danger is that you coat the wire with a carbon or other deposit and affect the performance..I would leave well alone if its not broke.. dont fix it!!
 

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Zotye Auto 1.5T T600 2016
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Hot film mass air intake means exactly that, hot film, and if you use chemicals on it then auf Wiedersein or good by MAF. Only clean by using compressed air.
 

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Outstanding Contributor W221 Moderator
2010 E350 P1/P2, 2008 S550 Designo, 2002 ML320
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Discussion Starter #8
Roger that, too late. ;)

It was not too dirty, just a quick spritz of the MAF cleaner and it came clean. I have not had a drive in it yet, off the work in a few. But the idle seems smoother (all in my head).
 

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eric242340 said:
Hot film mass air intake means exactly that, hot film, and if you use chemicals on it then auf Wiedersein or good by MAF. Only clean by using compressed air.
Hot film means hot film, and hot wire means hot wire, and he has the latter. There is no hot film in the LH engine management system in a 1995 S420, only a hot wire and it is much more durable than hot film in the HFM system.
 

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W639 Vito 110 CDI; Ponton 220S; VW Phaeton V10 tdi; 1995 S500 ex diplomatic car (gone)
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At least something electrical is more durable on the early ones!
 

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Outstanding Contributor W221 Moderator
2010 E350 P1/P2, 2008 S550 Designo, 2002 ML320
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Discussion Starter #11
gartracescort said:
At least something electrical is more durable on the early ones!
It better be, street price for the early MAF is $500+, the later model is $180 or something.
 

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1997 S600 (sold)
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dlafever said:
It better be, street price for the early MAF is $500+, the later model is $180 or something.
I understand that hot wire MAFs can be "rebuilt" by replacing the hot wire element. At least that of the Porsche 928 can be. There is a popular 928 forum guy that does the MAF rebuilds. I don't know if this is general for all hot wire MAF sensors. Would be interesting to see if the sensor used in the W140 is rebuildable. Hell, the hot wire W140 MAF sensor may be identical to the 928's hot wire MAF sensor. I have a strange feeling that lot of modern cars' Bosch MAF sensors are identical with the exception of the connector on the wiring.

Brett
 
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