Has anyone experienced any problems relating to K&N air filters not working so well and contaminating the MAF sensor? I have one in my '99 V6 tacoma and in my '01 Corolla Sport. I just replaced the MAF sensor in my Corolla a month ago as it puked out - got the check engine light and my code reader spat out P0171 (running lean). I took out the MAF and cleaned it but still got the P0171 a short while later so I took it to a dealer to have them read the code with their equipment and they told me I needed a new MAF. Got a new one and installed it and haven't had any problems since.

Now this past weekend, I was out on some logging roads with my tacoma and drove no more than 8 miles before getting back to pavement. The road was quite dusty as their was a lot of traffic on it. A short while later, I got the check engine light. I pulled over and pulled the MAF sensor out. It was completely covered in dust to the point that it was all white. I cleaned it off, unplugged the -'ve battery cable to reset the computer and came home. Sure enough on the drive home, the check engine light came on again. I plugged in the code scanner tonight and got the dreaded P0171 - same as the Corolla. I inclined to think that its the MAF on my tacoma as well. The only culprit I can think of is the air filter. Suffice to say, I'm dropping stock air filters back in but has anyone else had this kind of problem with the K&N's?

Masato

 

No problems here, but this is a topic that has had alot of attention in the past. Do a search on K&N and Amsoil. Lots o' reading.

I have a K&N FIPK open element and have had zero issues over 6+ years. I recently added the filter wrap (for keeping water splashes out)

I've had K&N filter on most of my vehicles and only had one problem that was my fault. I over oiled the filter on my 2000 Maxima SE and had a stalling problem. I had to clean the excess oil out off the MAF and had no ill effects.

 

Lots of people have had the same problem with K&N oiled cheesecloth filters and yes that code indicates a likely dirty MAF sensor.

Get yourself an Amsoil filter for your 3rd gen, clean the MAF and be done with it. Some have had to replace the MAF even after a thorough cleaning but the majority seem to be able to clean it and clear the code for good. The 1st and 2nd gen 4runners can run the K&N style filters because they use a completely different air management system (ie no MAF to get dirty).

 

The MAF usually gets dirty from over oiling the filter whether it's a K&N or an Amsoil;I've been running a K&N for over a year and just checked my MAF the other day and it looks fine.

 

My K&N FI kit has been fine for 7 years with no problems at all. I clean and oil the filter every other oil change depending on how it looks at the time if it looks bad or ive been in a dusty condition I clean it sooner, but I have not had any issues with my MAF... Where did you get your pre filter?? Ive always wondered what if I splash through a deep water hole! Thanks Matt

 

I say just go back to the stock paper filter. True, a K&N or Amsoil will last longer but the paper filter is a cheap part (even from the stealer) so you can just replace it regularly and get the same performance IMHO. And the performance gain from a K&N is minimal. Just my 2 cents'....

 

Highly recommend against using any oil bathed air filter with a hotwire MAF. It will simply get dirty quickly.

The big question is: did you clean it correctly? I've cleaned my MAF several times now, and it continues to work properly.

The visible bulby thing on the MAF module is NOT the MAF, it is the IAT (intake air temp sensor). The MAF hotwires (there are 2) are located deep inside the MAF tube thingy.

 

You guys have a different air meter? Mine looks nothing like the above pic. I have a 97 3.4, and the afm looks like a small missile suspended in the air tube with only a small hole in the tail of the missile. Looks for all the world like it uses some kind of venturi effect and Bernouli's law to calculate air flow. No hot wire anywhere that I can see.
BTW, I'm using the K&N, live on a dusty dirt road, and so far no problems.

 

I haven't had a problem with mine either. I just make sure I don't put too much oil on it...

 

Yes, the 99+ years are different than earlier.

 

Yours does use a hotwire just like the 99+ but the design is different and more difficult to clean than the later version.

 

i haven't had any problems either. had one for 14 years in my last truck and never had a problem with it.

 

I've been using K&N for years, to include the AirCharger on my 95 Taco. I purchased a new 4r not to long ago and droped in a K&N air filter. After reading the posts about K&N I thought I would take a look at mine to see how it was doing. With less than 3,000 miles and 5-7 days offroading, the secondary filter was extremely dirty! The K&N filter let enough dust through to make the secondary filter do all the work. Just "patting" the secondary filter with my hand reminded me of beating an old dirty rug with a broom. It was diiiiirrrrrrrty! No more K&N for me!

Which leads me to a question for you...does anyone know how to change out the secondary filter (4.0L, V6)? The mechanics at my local dealer said they've never done it before and that they didn't know how (???). I did talk with Toyota didn't I? Maybe I dialed Toys-Are-Us...???

 

I have had an K&N FIPK open element on my truck since the day that I bought it in 2000. It is a '96 4Runner V6. I clean and oil the filter when it looks like it needs it. Had the head gaskets replaced in February of this year. I asked the tech personnaly how the liners looked. He said that they looked like the day they left the factory. No ill effects from the K&N. The tech told me that anything that passes through the K&N filter will not be large enough to cause a problem. He said that people read too much and need to have a little more common sense. I beleive him. I just put a set of TRD headers on in September and had the whole intake apart. There was zero residue on the MAF or the intake tube. As far as I am concerned the K&N is a quality product. If Porsche recommends it then that is all I need to know.

 

i noticed when i was in Arizona for school that the upper part of the air box had a slight film of very fine dust, i put a little more oil on the filter and the dust stopped, i think that the extremely fine Arizona dust pulled most of the oil out of the filter and was allowing some dust by

 

did you use compressed air to clean the filter? cuz mine has been good for 3 years now