Please don't give me too much shit, this is more of a thread to help other people if they are thinking about a cold air intake (CAI).
I have been running a K&N CAI for almost 2 years now. It was a mod that was added before I really got into modifying the truck very much, and it was a result of some issues with the stock system not sealing and getting some crude in it. My dad had had good experience with K&N way back when, and I run their air filters on my stand up jet ski with no issue so it seemed like a good move though I didn't do much research at the time because I wasn't very involved with the 4Runner yet.
The intake is nice from the perspective it has a mean growl to it which I've come to like, and that I just have to clean it instead of replacing the filter (in retrospect it's probably cheaper for the amount of time to just replace a filter than go through the cleaning/drying/oiling process).
However, last summer on my way to USU to help a professor with some classes I had the MAF go out on me. We cleaned it and had no issues for 100 miles and then it died again so we replaced it, and then no more issues. This may or may not of been influenced by using an oiled filter, I never over oil the K&N but it's something to consider...
Now on to the main point of this thread. This weekend I went mudding with
@
Cartzo
and some other guys, our version of mudding consisting of muddy trails and giant puddles. After hitting one puddle really hard, I had a sudden drop in power as is associated with lack of air for the engine. Sure enough, the filter was totally wet and struggling to breathe.
This is not a current picture but from a few months ago, it illustrates how the K&N is setup and as you can see in the bottom left, the filter is completely open to the elements (unlike the stock system):
I was not entirely surprised the engine was starving for air based on the design of the intake, but after waiting awhile and the engine doing well we moved on. Fast forward and I my check engine light comes on when we are driving back, engine is running fine so diagnose it that my MAF is dirty and I use a scanner to confirm that. Yesterday, I go to pull the MAF to clean it and this is what I find:
Pull the filter and this is what my "filter" was NOT filtering out:
I have now removed the intake tube and this is my throttle body before the throttle plate:
I am going to write to K&N and throw some shit, because their supposed filter doesn't appear to do anything! I can understand it bogging down when it's wet, but letting sand and mud through the fabric filter is beyond me. Obviously I'm going to swap the stock unit back in now, until some point in the future when I can get a full on snorkel. However I can't recommend K&N any more, it works fine on my jet ski but that's operating in a clean environment where there is only water unlike my 4Runner.
Cartzo and I are planning to drive to CO from UT for spring break this Friday, which is a 500 mile drive. I am very concerned with the condition of my engine from all the shit that may of made it into the cylinders. I don't want to even drive it to a car wash to get the mud off (which has caused other issues that need to be sorted by Friday). As of now I will be pulling the throttle body and intake manifold and trying to clean as much of the intake system as I can.
I'd rather not see people being snotty and saying "I told you so", the CAI worked fine driving around town, but now that I go offroading upwards of 3+ times a week in conditions from snow to heavy mud and and pond sized puddles the K&N is showing its flaws and why I won't run it anymore.