z31 Filter and Throttle Body Mod DIY Guide!

[DeleriousZ]

First off this is a GUIDE and a GUIDE only!!! I take absolutely NO responsibility for any of your screw ups, or any harm done to your car! Right, with that out of the way, lets get started.

Alright... we'll start off with changing to a cone filter... pretty easy thing to do, but there's a bit more involved than the average swap..
First off, unscrew the 4 bolts in red and set them somewhere... like the garbage because you won't be needing them anymore... then loosen off the screw in green and pull the top of the airbox diagonally up and out to the left. Next, loosen the bolt in orange and remove the connector...



Up next comes the bottom of the airbox... there's 4 bolts that hold down the supports, 2 each end circled in yellow... unbolt them and remove the intake resonator (other box.)



Now, when you pull out the bottom box assembly (brackets should come with it) you'll want to snag 2 of the rubber bushings that the resonator sat on (if you're keeping the resonator) and keep them somewhere safe until it comes time to put the resonator back.



Well, that time is now, put the 2 rubber bushings onto the nubbins on the bottom of the resonator box and put it back into the intake tube. Now depending on the filter, you might have to have at the filter side of the resonator with a file or grinder of some sort... my weapon of choice was a half round bastard file, but whatever works best for you.
Sometimes it helps to put the filter onto the resonator before you place the assembly back into the slot, it's up you you tho, doesn't really matter.
The tricky part for me was getting the filter to sit right... the angle that the resonator was sitting at forced the filter to come in contact with the hood, so i had to rig up the metal strap you see in the picture below. I used 2 existing screws, so it worked out pretty well.



Now you're done! Don't forget to tighten up all the connections so nothing falls off when you're driving along.
Throttle Body section coming soon!!

[ExTrEmEDrIfT]

hey looks good nice instructions ..
keep up the good work..

[DeleriousZ]

RIGHT!! Throttle body time!! err... yeah time to get rid of that nasty restrictive 54mm throttle body and have a nice flowing 60mm one in place of it!!
Ok, first thing you're going to want to do is have a nice cool engine to work with so you don't burn yourself! You're going to need to remove the upper piece of intake piping for this, so it's best to start by backing off the clamps on the pipes that run to the intake piping (circled in yellow.) I found it was way easier to get the EGR hose (i think) off by pulling it off the engine side of the hose (red arrow) you may find differently, i don't know. Next you're going to want to loosen the clamp on the lower part of the intake(green arrows) and the 2 clamps(green boxes) that attach the piping to the throttle body (TB from now on.) Now is a good time to put a towel or something over the lower intake piping to make sure nothing falls down in there and gets sucked up into the engine when you finish.



This is what it should look like after the piping is removed. Next up is removing the TPS or throttle position sensor. To do this you simply unscrew it on the top and bottom, but be careful not to lose the screws, as they are needed later on when replacing the tps. Here comes the hard part... getting the bolts broken free from the TB (circled in pink) I found the best way to do this for the top 3 was to give it a few solid whacks with a nice large hammer, and for the 4th one, use a screwdriver set on top of it and hit the screwdriver with the hammer. You will need a metric allen key to unscrew the bolts, but i'm not sure what size, so you'll have to guess and test. I found that it required quite a bit of force to break the bolts loose even after hitting it with a hammer so don't get discouraged. they're all fairly easy except for the bottom left one. I had to flip the allen key around, grab the end with some locking pliers and really reef on it to get it loose.



You'll now need to remove the 2 coolant hoses that are feeding the TB. Over the years they've probably melted to the nipples on the TB so it might take some force to get them off, just be careful not to split them because replacing the hose on the left side is a BITCH (i'd know.) Now when it comes to the Stanza TB (not sure about the 240sx) the coolant nipples are facing a completely different way than on the 300zx, so you're either going to need to replace the hoses (not recommended) or just bypass it alltogether (easiest to do and might net 1-3 more hp lol.) What you'll need to do this is some 7/16th's(i think) fuel hose, 2 90 degree connectors that fit snugly on each end, and 4 correct size hose clamps.To complete the bypass, you simply need to fit the hose and clamps so that the coolant can flow freely from one hose to the other (circled in red.) Make sure you do it so the hose can sit above the throttle cables if you're going over the TB, i'm not sure if you can hide it underneath, but go right ahead and try if you feel it necessary. Once the TB bolts are removed, you might need to give it a few solid taps on the solid part of the TB to break it loose from the intake manifold. You may need to take a chisel or a screwdriver to the face of the manifold to clean up any excess gasket that was left behind, i was lucky and didn't have to. To completely remove the TB, you'll have to disconnect the throttle cables from it, to do this you put the cable at a 90 degree angle to the housing and pull it out sideways. You'll notice that it's quite dirty down the neck of the manifold, you can probably take some throttle body cleaner and a cloth and clean it out if you really feel the need, just make sure the cloth doesn't give off any fibres that could get into the engine.
(Notice the TPS screws circled in white in a nice safe place.. like i said before, these are pretty important.)



Time to put that big new TB back onto the intake manifold... here's where you can either go the easy way (just put the TB back on with the gasket and be done with it) or the hard way, which involves porting out the mouth of the intake manifold, if you want to do this, just ask and i'll tell you how, it's way too late for me to write it out.
To actually replace the new throttle body, i found it easiest to replace the throttle cables, then put the top 2 bolts though the tb and line up the gasket on it, then screw in the bolts in an X pattern(top left bottom right top right style.) Reattach the TPS making sure to replace it the same way it was installed on the previous TB. Now you may notice that the TB only has one small vacuum nipple on the side of it, at least mine did (blue arrows.) I've got no idea what this does, so i just blocked off the end of the hose and hid it away, seems to run fine with it plugged.



WHew! you're almost done.. now all you have to do is replace the intake piping and hook up all the hoses to it and clamp them down. Make 1 final check that everything is screwed down tightly and fire it up! You'll probably have to mess around with the idle a bit to get her running prime.. which is where i ran into problems... when i was attempting to adjust the idle adjust screw, the metal around the bolt snapped in 2.. so be sure that the assembly moves freely when you select your TB.

Tools Used:
2 flathead screwdrivers, one long and skinny, the other regular size
1 hammer
1 half round bastard file (for intake resonator)
1 pliers
1 allen key, not sure of the size
1 phillips head screwdriver
1 bent over short flathead screwdriver
2 14mm wrenches
1 3/4" drive ratchet
1 8" extension
1 10 mm 3/4" drive socket
1 needlenose pliers
1 some sort of surgical tool... handy for hard to reach hoses
1 pair locking pliers
i'm sure there's more, but i can't remember at the moment.



I repeat and strongly stressthis is a GUIDE and should be used at your own discresion, i assume absolutely NO responsibility for any harm to come to you or your car from following this.

HAPPY MODDING!

[RB25DETZ]

How's that new throttle body? is your idle way to high? you could ajust it if you didn't break it LOL. I'd also like to ask why put a cone filter on a car with almost 170,000miles and an engine that you are scared to go past 4k in? heh but it's all good I'm waiting for the turbo

[RB25DETZ]

"2 flathead screwdrivers, one long and skinny, the other regular size" you crack me up dude. you know they have sizing numbers on the screw drivers :P

[nissan_drvr]

You can mess with the throttle body, but the rest of the pipes remain the same...

[probehtr300]

so is there a noticable power gain, or differance u can feel after the TB/cone ????