The MAF Cleaning Thread

[az3579]

I figured I'd start a discussion on the topic of cleaning hot-film MAFs. A lot of people seem to think that it's possible to successfully clean a hot-film MAF (like the one on the E46 330's) without causing further damage. Along the same token, there are just as many people who say it is not possible to clean a hot film MAF, unlike the hot-wire versions which can be cleaned with MAF spray, and say that attempting to clean a hot-film MAF will further damage the unit, potentially making it worse.

All I have to go on so far is what can be read online, as well as the experience of personal friends of mine who work at various shops (one of which was a master BMW tech before he got laid off). While I do trust the word of experience people who have seen a lot more than we have (as just regular owners), I'd like more information.

The naysayers, ones who say it cannot be cleaned, are mainly the techs that I spoke to. I thought I also read it in some technical information for a Bosch hot-film MAF, but I didn't bookmark the info, so am going to treat it as though I've never seen it.

The ones who say they can be cleaned have claimed to have cleaned them by spraying them with MAF cleaner. These are the folks who were having problems with their MAFs. From what I've seen, there are a few who say it worked and left it at that. Then, there were the folks who sprayed them and just made their problems worse, or had the issue return shortly after.


So, I'd like to open the discussion to the populace here and see if anyone can provide hard data as to why these things can or cannot be cleaned. Anyone?


I don't have too much time to research this on my lunch break, but will do some more research tomorrow when I have more time and see if I can find examples of actual data on the matter. The purpose of this thread is data, so the more of it we have, the more informed we are! Ready, set, go!

[slater]

i cleaned mine with CRC SensorKleen the first week i had the car. grime came off. MAF still works. that was over 2.5 years ago. maybe i didn't spray enough to do any damage? maybe it doesn't damage it at all?

also, interesting (first post):

http://www.bimmerforums.com/forum/showthread.php?951602-TRY-THIS-on-your-MAF-before-dumping-it!

[NoVAphotog]

i cleaned mine with CRC SensorKleen the first week i had the car. grime came off. MAF still works. that was over 2.5 years ago. maybe i didn't spray enough to do any damage? maybe it doesn't damage it at all?

also, interesting (first post):

http://www.bimmerforums.com/forum/showthread.php?951602-TRY-THIS-on-your-MAF-before-dumping-it!

Plus one.

Cleaned mine during my initial maintenance regiment with the same stuff 2 years ago. No issues. I think it's fine to do a quick burst and keep it moving just get any dust and grime off.

[theothersawyer]

I was throwing codes and everyone on here said the MAF was the issue. Took it off and cleaned it with the CRC SensorKleen spray. Codes went away and never came back. It has probably been 6-8 months!

[slater]

I was throwing codes and everyone on here said the MAF was the issue. Took it off and cleaned it with the CRC SensorKleen spray. Codes went away and never came back. It has probably been 6-8 months!

awesome. it's the K in 'kleen' that does it.

;)

:cheers

[ELCID86]

I've cleaned mine a couple of times with MAF spray.


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[Sockethead]

I used CRC MAF cleaner as well a couple of years ago with no issues

[toddztoyz]

I am 2 for 2, in that I have used the same brand of cleaner and it failed on both cars. I tried it first on my ZHP and then on the 325Ci, and neither got worse, but neither worked. I ended up replacing both with a remanufactured MAF and that solved the problem on both cars.

[WOLFN8TR]

I clean my MAF every time I clean my air filter with CRC MAF cleaner. Never had any problems.

[Cadeez]

I clean my MAF every time I clean my air filter with CRC MAF cleaner. Never had any problems.

What he said...:confirmed

[az3579]

Okay, so after having had lean bank 1+2 codes again for the past few months, I found out that the MAF was "in need of replacement" again. I had already replaced it once in 2014 for the same exact issue. This time I removed it from the car and inspected it. Sure enough, there was oily crap all over it.

I love my GruppeM intake, even if it keeps fucking up my MAF. The sound is too intoxicating, but man do I hate the fact that aftermarket air filters like this use oil. What an idiotic design.

Since my MAF was "trashed" anyway, I had nothing to lose, so I went on a quest to find CRC MAF cleaner. I didn't want to use anything not designed specifically for MAFs, so it had to be this particular product. Walmart didn't have it. Advance Auto didn't have it. AutoZone, however, did.

Since everyone that said they have sprayed their MAFs said that they did little sprays here and there and went easy on it, I decided to do the opposite in the name of science. So, I doused the shit out of this thing, making sure every nook and cranny on the inside tunnel of the MAF was sprayed. I let it dry, and did it again, thoroughly spraying every single inside area including the sensor and the upper plate where it mounts. I let the whole thing dry overnight and installed the next morning, subsequently clearing the codes for my test run.

This was on February 22. It is now March 4th, having put 1000km on it since then, and the CEL is still off. I'm genuinely surprised, and now have to start wondering how long this will actually last. I'm going to see if this will last 'till my next oil change (which I'm severely overdue for one now anyway, so I'll reset the clock when I get it).

[3ZHPGUY]

Okay, so after having had lean bank 1+2 codes again for the past few months, I found out that the MAF was "in need of replacement" again. I had already replaced it once in 2014 for the same exact issue. This time I removed it from the car and inspected it. Sure enough, there was oily crap all over it.

I love my GruppeM intake, even if it keeps fucking up my MAF. The sound is too intoxicating, but man do I hate the fact that aftermarket air filters like this use oil. What an idiotic design.

Since my MAF was "trashed" anyway, I had nothing to lose, so I went on a quest to find CRC MAF cleaner. I didn't want to use anything not designed specifically for MAFs, so it had to be this particular product. Walmart didn't have it. Advance Auto didn't have it. AutoZone, however, did.

Since everyone that said they have sprayed their MAFs said that they did little sprays here and there and went easy on it, I decided to do the opposite in the name of science. So, I doused the shit out of this thing, making sure every nook and cranny on the inside tunnel of the MAF was sprayed. I let it dry, and did it again, thoroughly spraying every single inside area including the sensor and the upper plate where it mounts. I let the whole thing dry overnight and installed the next morning, subsequently clearing the codes for my test run.

This was on February 22. It is now March 4th, having put 1000km on it since then, and the CEL is still off. I'm genuinely surprised, and now have to start wondering how long this will actually last. I'm going to see if this will last 'till my next oil change (which I'm severely overdue for one now anyway, so I'll reset the clock when I get it).

Thanks for sharing. I'll have to try that!

Mine has been on for a while and runs well enough not to convince me to spend the hundreds to replace it.


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[BMWCurves]

Ugh, is that what a GruppeM or any oiled filter does to the MAF?

[orange260z]

You have to be careful not to over-oil the filter. Follow the new instructions carefully and afterwards wrap the whole thing inside and out in paper towels and let sit for the night. The paper towels will wick off any excess oil. Never had a problem this way.


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[az3579]

Ugh, is that what a GruppeM or any oiled filter does to the MAF?

Any oiled filter will do this.



Mine has been on for a while and runs well enough not to convince me to spend the hundreds to replace it.



The car was running great despite having the light on, so it was the same exact situation for me. :dunno

The funny thing about it is that my emissions test AND registration was due when I was dealing with the light being on. Since the car MUST pass emissions to be able to be registered, you can see how that was going to be a problem. I don't know how I got away with it, but I ended up clearing the light, driving it for a full day (which is enough time for it to run its cycle), and then going to get the emissions test done at the end of the day before the light came on. Surprisingly, it cooperated, and passed the emissions test just fine. Then, the next day, it came on again at the first crank of the day. lol

Talk about good timing.

[3ZHPGUY]

Any oiled filter will do this.




The car was running great despite having the light on, so it was the same exact situation for me. :dunno

The funny thing about it is that my emissions test AND registration was due when I was dealing with the light being on. Since the car MUST pass emissions to be able to be registered, you can see how that was going to be a problem. I don't know how I got away with it, but I ended up clearing the light, driving it for a full day (which is enough time for it to run its cycle), and then going to get the emissions test done at the end of the day before the light came on. Surprisingly, it cooperated, and passed the emissions test just fine. Then, the next day, it came on again at the first crank of the day. lol

Talk about good timing.

I dreaded those emission tests on Ohio. Such BS, your car was required to pass that every other year but, no safety inspection requirement. Just another thing to take money out of your pocket at $20.00 a year added to the license plate fees.

And Yes you did time that great. Now you should be good for at least 364 days.

[orange260z]

The difficult choice here is that the oiled ones apparently flow AND filter better than the dry ones.

An oiled AFE has been on the BMW since spring 2013 with no issues; and I've run K&N/HKS/AEM/Apexi on other cars for years without any issues, I was just really careful with the oiling. I like when the filter is white and the oil has color to it, so that you can tell when it's wicked all over the filter. The HKS was a bitch because it was green, so there was no visual indication of the oiling.

[holyc0w]

I dreaded those emission tests on Ohio. Such BS, your car was required to pass that every other year but, no safety inspection requirement. Just another thing to take money out of your pocket at $20.00 a year added to the license plate fees.

And Yes you did time that great. Now you should be good for at least 364 days.

Sounds like the IL emissions test. They plug in and check for any codes. They used to hook up the exhaust to their testing equipment, but I don't think they do that anymore at least on passenger cars. There's no charge though, at least not direct.

[az3579]

Sounds like the IL emissions test. They plug in and check for any codes. They used to hook up the exhaust to their testing equipment, but I don't think they do that anymore at least on passenger cars. There's no charge though, at least not direct.
For us they put the car on a dyno. A CEL is an immediate fail. The exhaust pipe sniffer is only for OBD-I cars here. This is the method they used for my E30...

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[holyc0w]

I looked up the testing program. The site mentions:

Most 1996 and newer gasoline-powered passenger vehicles are subject to emissions inspections after they are four years old
Not subject to emissions: Vehicles of model year 1995 or before that were in compliance with the Illinois Vehicle Emissions Inspection Law on February 1, 2007.

I'm sure that's super effective protecting the environment. :rolleyes

It would have been nice to have that when my brother had his 1988 Maxima. The catalytic converter was changed and it still barely passed the exhaust test.

[Reasoned1]

I've had an oiled K&N filter on for about a year. I haven't had any issues, and I regularly spray the piss out of the MAF sensor with CRC MAF sensor cleaner.

[ELCID86]

That's great BP. And now I don't feel as bad about using MAF cleaner on mine!