I'll go ahead and touch on this, since I have an S14, and I did this about a year and a half ago, took pics, but they didnt come out good and I was too lazy to do a write up. Good job on the write up, btw. I really like that paint finish. I did mine in black but i want to do them in that color (stock cast looking) when i build the motor...maybe have it cleared too).
Anywho.
The EGR return...for those wanting a cleaner setup, you can pull the EGR return (the rusty looking thing that alot of people just block off with a plate) and you can have the 1" x 1/2" hole underneath welded closed...or you can get creative and make a blockoff plate there as i did since i had no welding access then. RTV is your friend. It's actually easy to where the EGR runs by finding that little bulge in the casting with the 4 big allen key screws. dont bother messing with it...if u feel with ur finger you can actually feel the holes where the egr dumps the exhaust gases into the runners. theyre very small probably 1/4" diameter at best. on S14's, that big screw sticking out of the EGR "bulge" will instead have a 2 wire probe inserted there. the good ole' EGR temp sensor (its a mini EGT
)...this bastard will make you throw all the EGR check engine lights on an S14, esp OBD-II model. i cut the wires and left it as the plug. eh.
The secondary IACV thing talked about (the branched off portion) is the IACV-FICD. this bumps your idle up when your air conditioning turns on. so if you dont have a/c, you dont need it...but removing it means youd have to run either a full softline from the IC pipe (intake on n/a motors) to the main IACV unit, or cap off the "branch" and blockoff/weld the FICD hole shut.
The little line that dumps into the lower plenum behind the throttle body is the EVAP purge return. basically after your gas tank vapors settle into the charcoal can/EVAP can (on later models), the expunged air is sent to the intake manifold via this line, etc etc. and for reference, charcoal canister was behind the driver headlight up until 1996 when it was redesigned and moved to the passenger rear fenderwell, behind the wheel, under and beside the trunk...pulling that stuff out sucks, and if you're fiesty, have fun pulling that evap harness out of the trunk and interior (if youre anal like i am...or you aspire to wire like Russ
) you can wire in a resistor to this too to trick it if you want but it wont make your car run better or worse if you have the CEL or not.
The throttle body coolant lines arent required...if you follow the "small" coolant hoses, you'll see it branches off the main coolant lines, basically flows back to the rear portion of the lower plenum, makes a U-turn (depending on year of motor, you'll actually see 2 metal 'elbows' that flow the coolant through a tab-like portion of the lower plenum casting - not that it will make a big difference but thats a slight amount of hot coolant heating the lower plenum...[good work, nissan engineers]) then it flows back up front and through the throttle body and tee's back into the main lines. i bypassed it, living in florida, and was able to "entice" one of the leftover lines to bridge the beginning and end and discarded everything in between, including the elbows and etc. NOTE!!! for those of you in cold climates, this might affect you if its somehow cold enough to freeze your throttle plate closed overnight or something i dunno.********
The 2 sensors on the upper coolant neck are the ever so important, and often frequent problem causing, coolant temp sensor, and the other is a **** 1 wire feed for your stock dummy gauge in your cluster. you can ditch the cluster one and weld shut, grind, polish, block off with a bolt...that one if you have an aftermarket water temp gauge and dont mind your stock cluster one not working...OR you can probe the aftermarket gauge in there. makes a cleaner install than buying those hose adapter things that you splice in the upper radiator hose.
The PCV system makes it hard to route it elsewhere due to the 4 nipples and being on the underside (lucky SR owners have 2 return nipples and its on top). that little box on the side of the block is an oil seperator and the pcv valve in there is like 8 bucks. if u have your manifold off might wanna pull it and check it (blow through the one end and then the other make sure its only opening one way - also clean it first before you put ur mouth on it lol). again if you have welding access or some really big vacuum caps (i decided not to opt for caps i didnt want any boost to leak or blow one off (and their a b!tch to reach), its best to weld them shut after cutting them off at the runner cast, then run a line from the pcv valve to a Tee, run the valve cover blow by vent to the other end of the Tee, then run that to a catch can...then run the other end of the can can to the intake pipe (NON PRESSURIZED PIPING!!!) and voila you have a functioning pcv system without the oily residue building up in the intake runners and head (be sure to check the catch can every so often, depending on how much blow by you have and how much oil gets past the pcv valve itself).
and a few notes on obd-II (late 95 models and up):
on the lower plenum behind the EVAP return hose and in front of the IACV-FICD unit, there is a black box similar looking to the FICD unit. it is part of the EVAP system and can also be ditched. theres a few sensors up top on obd-2 models that are ditchable too, which allows you to remove the fuel hardlines on top of the manifold and run softlines from the filter straight to the rail and from the regulator end of the rail to the hardline that returns to the tank under the car (bottom firewall by tranny tunnel).
also regarding obd-2 crap (might be all s14's not sure), you can remove the 2nd o2 sensor and the crank angle sensor (located on top of the bellhousing (hard to get to but good to do during a tranny/clutch swap)) without any ill effects but some CEL's.
and there's 2 sensors by the fuse box and passenger side strut tower...one is a BARO solenoid and the other is a MAP sensor...yes a MAP sensor...but wait...KA's are MAFs based, right? Indeed....that means that the MAP-BARO and the MAP-Absolute Pressure Sensor are there so if you live in a state that has emissions...these little clutter boxes help you pass the smog tests. other wise.....TO THE TRASH!
and to verify that you can do all that stuff (regarding the removals and OBD-2 crap), I have done all of it (sans crank sensor yet), and the only ill effect is that i have about 10 check engine codes.....but my motor ran fine n/a with it gone, and it still runs fine pushing boost. upon 1st impressions (while n/a), it seemed smoother during normal acceleration, maybe due to the EGR and EVAP systems not purging crappy air and clicking on and off between WOT, cruise, and Idle, but the butt dyno isnt purely accurate anyways. I'm still running an OBD-2 ECU as well. I was going to repin 3 wires and run an OBD-1 s14 ECU, but since i am going to be getting a ROM tune soon that requires use of an S13 ECU, i'll wait til then. but it should all still function fine, I do hear some OBD-1 s14 guys dont have as many check engine lighst and some none at all. Ill post an update in a month or so if i can get the ROm tune by then.
