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       Shawn's Custom K&N Filtercharger
Instructions for Toyota Pickups and 4Runners
     Note that this kit was fitted for the 4-cylinder EFI 22RE engine, not the carbureted 22R version.  I haven't tried a V6, so these exact instructions may or may not work with one.  The V6 AFM housing looks to be the exact same, so  you should be able to use these instructions with only slight modification --perhaps by using a filter and adapter with different diameter and making slightly different aluminum supports.  I've been using this setup since around 06-1998 and have had no problems at all.  I had another one on an '87 4Runner I used to own, but I sold the truck and sold the filter to a buddy. It fit without modification on his '86 Celica and has been running it since 07-1999 with no problems either.  I've been running another filter on my '90 Toyota 4Runner 22RE since early 1999.
     I purchased K&N filter part number RU-2520 from a local store (around $50 but I think I got ripped off).  The filter is cone shaped with a mounting diameter of 4".  What  you need to do is find something to mount the filter onto which could then be mounted to the mass air sensor .  I went to Walmart and looked at cups, bowls, and thermoses.  What you will need is something that is round, but straight sided like this:
|                      |    right
|                      |
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not cone shaped like this (the filter would slide off):
\                          /   wrong
 \                      /
  \                  /
   \_______/
     I chose the Thermos brand Hot/Cold thermos bottle. They sell two sizes. I purchased the smaller size which runs around $6.  Both sizes of thermoses have the same size cap in a 4" diameter to mount the filter onto.  This specific brand thermos cap is really not even the key to making this kit.  The key is to find something that is cup shaped with a 4" diameter. Folger's metal coffee cans and PVC end caps also have a 4" diameter.  I know other people who have successfully made kits with the PVC parts. 
 _|                      |_
\                          /
 \                      /
  \                  /
   \_______/
    The K&N filter is shaped similarly to the cone shape above.  The open end of the filter needs to slip onto the open end of the thermos cap.  The closed end of the thermos lid (that probably says "Thermos" on it) faces the air mass sensor.  Unbolt the three bolts holding down the filter box, and remove the 4 nuts holding the filter box onto the air mass sensor. This next part is a bit hard to explain, so if it doesn't make sense let me know.  Take the rubber gasket and trace the square hole onto the thermos lid top.  When tracing the square hole on the thermos lid, make sure the holes that need to be drilled for the two studs that are closest to the front of the vehicle have enough room to fit inside the lid, with a little extra room to mount the two nuts inside the lid(the nuts will sit on the perimeter on what would have been the bottom of the thermos cup where your coffee would have been). 
     You may notice that if you try to line up all four studs so that they will go inside the thermos lid, there will not be enough space for all 4 studs and posts to fit.  You will need to do a little bit of drilling.  Between the two studs that are towards the rear of the vehicle are two deep grooves, voids, channels or whatever you want to call them in the air mass sensor-to-filter mounting surface.  One is roughly shaped like a "Z" but straighter.  I drilled a new hole in between the original studs in the "Z" shaped channel, being careful to make sure I drilled through not to the inside of the sensor housing, but through to the other side of the mounting flange (still external). This may not make sense until you are actually looking at it.  There is only one spot within the "Z" shaped channel where you can drill through to mount a stud.  Take out both the rear studs with pliers or something, thread one back into the new hole or use another bolt/nut combo if you like.  I don't know the drill bit size, I just eye balled it.  When looking at the air mass sensor from the driver's side in it's original location, the new stud pattern will form a triangle pointing rearwards, and this triangle will now fit within the thermos enough to get the nuts on.    Drill the 3 stud holes in the thermos lid, cut a small hole in the gasket for the new stud, put the gasket and lid on and tighten down.  I also used a little RTV sealant for assurance.
     The new filter is longer then the original filter box, and would be an impossible squeeze to put the K&N on without a few more simple adjustments.  You will have to loosen up both sides of the that big black plastic air intake tube that goes over the top of the radiator to the throttle body and snug it up at both ends enough until you can slip the filter on.
     With the filter assembly installed, you will notice that it would just flop around since the fender mounts from the filter box are gone.  Temporarily, I used a bungee cord to hold it in place. But for a permanent install, I used a 3/4" aluminum bar, drilled two holes--one to mount back at the fender using one of the original bolts, and the other to mount at the hole on the front side of the air mass sensor.  You could do anything you want here to use as a support. This is just what I chose.  '89 and newer pickups and 4Runners may need a slight alteration. Some models have a secondary plastic/rubber hose that runs along with the larger plastic intake tube from the air filter box to an emissions component below the throttle body. I cut the plastic hose and piped it directly into the larger intake tube. 
    Another option is to put on a fuel filter, diff breather filter, or something similar and tie it into the plastic tubing after the air mass sensor.  I haven't tried this methog though.  Or you could do something of your own design, but it won't be hard to do.  This may all seem lengthy and complicated, but it only took me less then an hour and I was winging it.  Of course, if you have any troubles send me an E-mail and I will be happy to answer any questions.  And after everything is done you will have better mpg, slightly more power, a beefier sound, and a thermos that still works. 
    Below is a snapshot of the fiinal product.  You can see there is plenty of room to remove the filter without having to take the AFM out.  If you don't snug up the plastic intake tubing, you won't have this much clearance.  You can see the Thermos lid (white) inbetween the filter and AFM housing. 
    I"ve received several E-mails from people who tried this and it works!  Some of them have gotten all the parts for only $50 too.
Let me know how it turns out!
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