AIV Repair/Removal, sticky?

Post by **p00t** » Sun Jun 22, 2003 9:05 am

Reasons for removing:If reed valves become gunked up in the AIV unit, exhaust gas will be allowed to flow into the intake. This can cause your cars idle to bop or drop below what it’s supposed to, also can cause slight stumble during acceleration. Deposits from exhaust can coat MAS and cause ECU to read the wrong amount of intake air flowing past it.

What it does:(Taken from service manual, called PAIR valve, on these boards its called AIV, dunno why.)

Pulsed Secondary Air Injection (PAIR) ValveThe PAIR valve sends secondary air to the exhaust manifold, using a vacuum created by exhaust pulsation in the exhaust manifold. When the exhaust pressure is below atmospheric pressure, secondary air is sent to the exhaust manifold. When the exhaust pressure is above atmospheric pressure, the reed valves prevent secondary air from being sent back to the air cleaner.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

The valve also works in tandem with a solenoid valve which controls whether it’s on or off.

Pulsed Secondary Air Injection (PAIRC) Solenoid ValveThe PAIRC –solenoid valve cuts the intake manifold vacuum signal for PAIR valve control. It responds to the ON/OFF signal from the ECU/ECM. When the solenoid is off, the vacuum signal from the intake manifold is cut. When the ECU/ECM sends an ON signal, the coil pulls the plunger downward and feeds the vacuum signal to the PAIR control valve.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

What you will need:1. Ratchet with small and large extenders for the ratchet pieces2. 10mm ratchet piece, you can try to use US sizes, but be careful not to strip the bolts3. Philips-head screw driver4. Flat-head screw driver5. Large bolts or stoppers to plug up hoses.

Location of AIVOnly the older s13 hatchback model 240sx’s will have this unit, Nissan realized it was almost pointless and caused problems as it aged, so they discontinued it in the s14 and s15 lineup.

The entire assembly is on the right hand side of the engine (looking from front of car), it’s comprised of hoses, a black plastic resonator, the metal AIV unit, solenoid unit, and black bracket which bolts everything to the car.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

First you need to unbolt the black bracket holding everything to the car. It’s attached with 3 bolts, 2 above the AIV, and 1 below. The extenders will come in handy here, other wise you have to use one of those single piece wrenches, or a small ratchet.

When the bracket is off, loosen the hose clamps for the tubes going to and from the resonator (2 hoses, 4 clamps). Push the bracket forward to gain easy access to the bolts holding it on. Unbolt the resonator (2 bolts), and pull it off from the hoses and set hoses aside.

To remove the AIV unit, first unbolt it (3 bolts), then pull off the small vacuum line connected to the top. Pull hard to pop it off, it shouldn’t rip on you, it’s a tuff little hose. Next, Nissan decided to use a metal clamp type of holder on the hose under the AIV, why? To piss you off. You will need to twist the AIV upside down or sideways to be able to remove the clip. Stick the flat head screw driver in-between the part of the clip where it sticks up and twist, pull, and push to loosen it. At this point you can remove it or just slide it down the hose.

Your last adversary is the solenoid, which is held on by one last bolt. Show those hoses no mercy as you pry them off. Wiggle the electrical connector back and forth while pulling to disconnect it.

At this point you have 2 roads to take. You can clean the AIV and then put everything back together or plug up everything and leave the AIV off,

To clean the AIV, take off the screws holding its two halves together (be careful, they are easy to strip!). Take apart the reed assembly, carefully taking note how it’s put together, and polish/clean them using steel wool and carb-cleaner/gas. If they are deformed you can bend them back slightly yourself, or buy new ones.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

If you wish to leave the AIV out you need to plug up every opening left. You can ghetto-rig it like I did, or you can do it clean and proper with some sort of stopper for the openings. Either way you will have to improvise with materials around your garage, or you will have to take a trip to the hardware store to find stuff.

Here’s a pic of the Atmospheric and Vacuum lines that went to the solenoid, I used some little screws to plug the line up, then I tied it down to the evap-line, which travels from the gas tank to the carbon canister in the engine bay.

Hopefully your lines have little colored bands on them, which will help you when reconnecting them to the solenoid. Make note of this before you disconnect them however, mine were faded almost to the point where you couldn’t tell what color they were. If there’s no bands or they are badly faded, make a mark with something so you know where it hooks back up!!!!

-Red plugs into the bottom of the solenoid (vertical)-Blue plugs into the top of the solenoid (vertical)-When reconnecting the AIV its hose will have no color, it plugs into the side of the solenoid (horizontal)

Post by **p00t** » Sun Jun 22, 2003 9:05 am

Here is the exhaust hose; you can plug it up with a bolt or some other stopper. I reused some of the clamps to make sure it wasn’t going to budge. Don’t worry about it shooting out of the hose, there is very little pressure in the exhaust, just make sure none of that exhaust is being vented into the engine compartment, okay?

The clean way to do this is to weld up the opening where the metal tube connects to the down pipe. I did not have a welder or a bolt that would fit the opening

.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

Last but not least, is to plug up the hole going to the air-filter and tie-down the electrical connector that went to the solenoid.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

Heres the whole gang getting their last bit of sunlight before they are put in the bag and tossed to the corner of the garage.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

I highly recommend saving the parts, if you have trouble with emissions when you go for inspection you may have to bring them back out, clean the AIV, and install them again. Though all it does is supposedly help the cat warm up faster.... who knows.

If I missed something or just plain ****ed up, let me know!

Post by **s0ldats** » Sun Jun 22, 2003 9:05 am

damn good write up. anyone have any trouble with cali emissions when they removed this?

Post by **encasemyheart** » Sun Jun 22, 2003 9:05 am

p00t wrote:Here is the exhaust hose; you can plug it up with a bolt or some other stopper. I reused some of the clamps to make sure it wasn’t going to budge. Don’t worry about it shooting out of the hose, there is very little pressure in the exhaust, just make sure none of that exhaust is being vented into the engine compartment, okay?

The clean way to do this is to weld up the opening where the metal tube connects to the down pipe. I did not have a welder or a bolt that would fit the opening .

I followed the same directions but here on the exhaust hose what I did was remove it completely. If you follow this hose it turns metal and leads into the exhaust downpipe. Right where it connects to the downpipe there is a screw on thing, unscrew it (I couldn't get a 19mm wrench over it, I used a monkey wrench, but it seems to be 21-22mm) Now that it is off the whole exhaust hose comes off.

Now you have the metal hose with the screw on thing on the end, you have to cut the metal hose (I used a hacksaw) to get the screw in thing off. Inside the hole in the downpipe where the hose was screwed in there is a small lip inside. Put 2 nickels (1 might work) in and they cover the hole completely and they stay against the lip. Screw in the screw on thing that you cut off in the previous step and tighten it down.

Now you don't have that long metal hose and rubber tubing going nowhere in your engine. It looks alot better now. Only thing is since you cut the metal hose it is not reversible, but if you need to reverse it, it should be very easy to locate another metal hose at a junkyard.

I just thought I should explain the '2 nickels method' because I didn't know what anyone was talking about when it was explained in short. Also this method makes everything easier to remove initially, believe me.

If you didn't understand what I meant, you will when you unscrew the thing from the downpipe.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

sweet!

i had heard of the method, now i know exactly how it works. once im sure emissions are ok im definately doing it!

Post by **240SXer** » Sun Jun 22, 2003 9:05 am

I'm gonna remove it from my 91' tomorrow.. Did anyone have good luck with it yet? Hopefully it's part of my problem..

Post by **s0ldats** » Sun Jun 22, 2003 9:05 am

p00t wrote:sweet!

i had heard of the method, now i know exactly how it works. once im sure emissions are ok im definately doing it!

emissions is what's keeping me from doing this mod.... i live in cali... anyone in california do this?

Post by **240SXer** » Sun Jun 22, 2003 9:05 am

I'm about to do it and i'm in Cali. But then again I smogged the car about 2 weeks ago

Post by **Boricua** » Sun Jun 22, 2003 9:05 am

FINALLY!!!!!!

I have some problems w/ AIV, i clean twice, and i didn´t know it can be removed:ylsuper

well mine is a 1990 Ka24e, 90,000but i have a K&N FIPK Performance Systems (Do the trick!!!)

can i do this????

How about emissions? It gonna smell really bad?:help

Post by **encasemyheart** » Sun Jun 22, 2003 9:05 am

No it shouldn't affect emissions at all once the car is heated up from what I'm told, and I don't know anyone who takes their car to get tested cold.

When you remove completely it looks really clean, the only way you would know anything was there is the single plug that's hanging and the bolt holes in the shock tower where the AIV held on to. Plus if I ever have to change the O2 sensor or something else that the AIV was blocking, it will be extremely easy.

BTW the whole thing start to finish took me about 40-45 minutes, that's with a big chunk of time cussing at the metal pipe because the hacksaw blade was kind of dull and not cutting it well.

If I had to do it again I'm sure it would be done in under 20 minutes total.

Post by **240SXer** » Sun Jun 22, 2003 9:05 am

Okay. On my 91' I unplugged the electrical connecter, removed and clamped the 2 bottom hoses, and clamped the intake hose. I didn’t want to remove the whole assembly so I didn’t. Everything is there; it's all just bypassed. However, I didn’t remove the hose that goes from the exhaust to the AIV. The solenoid will not actuate and it won't do anything, right? If it's an issue I can seal that too, it'll just take a lot more effort.

It's a big difference in driving. It has tons more low end, it gets the big jolt of power at like 3.5k just like my 95 does, but it has just as much low-end power (below 3k). I think that was my only issue.

Thanks everyone for the help. It worked great.

Post by **encasemyheart** » Sun Jun 22, 2003 9:05 am

With everything else blocked off and the solenoid unplugged it shouldn't hurt to leave the exhaust hose connected to the AIV, just make sure everything is blocked off.

Good stuff!

Post by **encasemyheart** » Sun Jun 22, 2003 9:05 am

Also here are a couple pics of my blocking off of the vacuum tubes, I used screws and epoxy instead of wire and stuff, it looks alot cleaner that all that wire and stuff.

Post by **240SXer** » Sun Jun 22, 2003 9:05 am

I got actual hose caps

Except I couldnt find one for the big air intake hose so I just put a little cap inside it and tightened the clamp on it like crazy. It works well but it looks ghetto.

Post by **Chingon** » Sun Jun 22, 2003 9:05 am

so you just take that **** off and not replace it with anything?

Post by **p00t** » Sun Jun 22, 2003 9:05 am

you plug up the holes left.... did u even read through the thread? all the device does is help the cat warm up faster...

Post by **corn322** » Sun Jun 22, 2003 9:05 am

and, if you don't plug the hole in the exhaust manifold, it will make your car sound like a lawnmower.

mine unscrewd itself a few weeks ago on the highway. people where giving me looks because it was so loud.

Post by **corn322** » Sun Jun 22, 2003 9:05 am

also, what about the electrical connector going to the valve? did you just leave it hanging around in the engine bay?

Post by **driftn240** » Sun Jun 22, 2003 9:05 am

I was wondering if anyone noticed any throttle response or other changes after this mod? Just seeing if I should look for any changes after i do it.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

you unhook the connector to the solenoid and you basically just leave it there, ecu doesnt throw any codes

it will only help your idle/low rpms if it is malfunctioning in the first place, and it depends on how badly it was gunked up.

Post by **sammy** » Sun Jun 22, 2003 9:05 am

hey p00t, you could also trace the two small hoses across the radiator fan shroud to where they connect to the ECCS, remove one hose, cut the other hose so it is long enough to connect to where you removed the first hose.......and voila.......even less clutter

ummmmmm..........does this make sense to anyone?

Post by **RedDario** » Sun Jun 22, 2003 9:05 am

I just removed mine, and it must have been real gunked up because now my idle is nice and smooth. Also, the hesitation on acceleration seems to have gone away. I'll drive it for a few days and see what happens.

Post by **p00t** » Sun Jun 22, 2003 9:05 am

sammy, if your ambitious enough, go for it, i think one of the hoses traces back to the intake, not sure where the other goes (one is vacuum other is an atmo line). as long as u plug up whatever hole is left when u remove the hoses its all good

.

AIV Repair/Removal, sticky?

AIV Repair/Removal, sticky?

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