aiv --- air induction valve... what?!?!!?

[ssnnooppyy]

Here's the skinny.... I have a 90 240sx, with a severe hole in the top of what Chilton's (sorry to use the 'c' word here) calls an air induction valve. It seems to be part of the egr system, and is now the scourge of my existence. No Nissan dealer knows what the heck I'm talking about, and every parts house says "go to a dealer". HELP!!! Can I run the car without this setup? How do I remove it all if so??? OR, where do I get this dern thing? hhhheeeeeelllllllpppppp. please.

[C-Kwik]

The AIV system is not part of the EGR. You can probably find the part out of a wrecked S13.

[mattlord42]

Is the AIV the black box thing that is screwed onto the driver's side fender that pumps exhaust into the airbox? If so then i just cut the hose at the exhaust end, undid all the screws that held it to the fender and removed the hose at the airbox. Then I plugged the pipe that comes out of the exhaust. Car runs just as well as it did when the damn holey thing was in there.

Matt

Edit: I don't know if this would be such a great idea if you actually have to pass emissions testing.

[ssnnooppyy]

Yes, that's the "black box thing". The part in question is the top-hat looking device that is held on by a strap with two screws, and sits on top of the device right below that "black box thing". The part has a huge hole eaten through the top of it, and other than an annoying rattle from the exhaust sound, the car seems to do okay. I just didn't know if it would cause problems down the road, or if it was an annoying and relatively unneccessary part of the emmisions system. I live in Oklahoma, so no vehicle inspections of any sort (just random checks by hiway patrol when deemed necessary). My inclination is to cut it all off, and weld it all shut!

[ssnnooppyy]

The AIV system is not part of the EGR. You can probably find the part out of a wrecked S13.

I would love to find that in a wrecked s13, but unfortunately, there's a total of three, yes, 3 junkyards that have a 240 near me, and two are 95s. The thrid one has been picked over so bad that I have given up. Yeah for Oklahoma!!!

[mattlord42]

Yep just go ahead and cut it off and weld it shut. That's what i did because mine had the same problem. My car still runs just as well as before.

Matt

[erich]

The AIV is to help the CAT light up faster. When there is vacuum in the exhaust and the ECU turns it on, the AIV lets clean ait INTO the exhaust allowing the CAT some more oxygen to light up faster. I removed it on my KA-T and passed local emmisions testing fine,

[C-Kwik]

The AIV is to help the CAT light up faster. When there is vacuum in the exhaust and the ECU turns it on, the AIV lets clean ait INTO the exhaust allowing the CAT some more oxygen to light up faster. I removed it on my KA-T and passed local emmisions testing fine,

Actually it is designed to burn off excess hydrocarbons by adding more oxygen. Not just when the Cat is cold. When I had an S13 and had a failure of a part on it, the hydrocarbons shot up so high my car was labelled a gross polluter. And this was when the motor and cat was at operating temperature.

[C-Kwik]

I would love to find that in a wrecked s13, but unfortunately, there's a total of three, yes, 3 junkyards that have a 240 near me, and two are 95s. The thrid one has been picked over so bad that I have given up. Yeah for Oklahoma!!!

Try http://www.autogator.com or http://www.ninfiniti.com. See if they have what you are looking for.

[float_6969]

The purpose of the A.I.V. (Air Induction Valve) is, to quote the FSM, "The air induction 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 (negative pressure), secondary air is sent to the exhaust manifold. When the eshaust preussure is above atmospheric pressure, the reed valves precent secondary air from being sent back to the air cleaner." This is what the valve does. To quote the FSM again, this is WHY it does what it does, "...The air induction valve is controlled by the ECCS, corresponding to the engine temp.. When the engine is cold the AIV control system operates to reduce hydrocarbons and carbon monoxide levels. In extremely cold conditions the AIV control system does not operate to reduce after burning. This system also operates during decelleration for the purpose of blowing off water around the AIV." So..... What does all this jargon tell us? Basically, when there is a vacuum in the exhaust manifold, the valve opens to allow air into the exhaust manifold to reduce HC and CO levels while the cat is warming up. After it has warmed up it only activates to blow water off of the valve. The reason that you have a hole in the valve in the first place is either due to the valve being bad for quite some time and the water oxidized through, or brake fluid (a strong reducer) came into contact with it and stayed in contact with it for quite some period of time. Also, if you find that you have exaust blowing back into your air box, you need to replace this valve. The whole unit doesn't need replaced, just the valve on the top that the vacuum hose connects too. Very simple job, takes less than 10 min. It's a cheap part and it will keep your airbox clean and allow your cat to work properly until it warms up. If you need a part # I can get it tommorrow.

[float_6969]

Yes, I'm the wordiest person I know. (Is wordiest even a word?)

[ssnnooppyy]

Why yes, come to think of it, wordiest is a word.... or at least it is now!!!! I appreciate all the info. I am still inclined to shut the "hole" thing off, but in light of "proper operation" I may invest in a new valve. I will check the websites offered, and even forge ahead with my junkyard misfortune. I recently put on a cone type k&n, with a modified version of the bracket that attaches the factory air box to the mafs, and to my chagrin, no place to hook the hose. That's how I found the hole in the aiv in the first place. I was tracing that vacuum line, and voila!!! Now it has turned into, well, the thread you are currently reading and replying to! Thanks, and I'll post in a few days to let the news spread of my success and/or failures!!!!

[C-Kwik]

I've replaced that part in 2 S13's. It's about $30. And both cars had HC emissions problems when the valve was bad. Even after the cat was warmed up enough. I believe what you have read in the FSM, but my experience tells me that there is more to the AIV then cat light off.

[Slickdrift78]

Is anybody still tracking this thread? So I had to get a different engine loom harness and in order to re-route the harness I had to depin the SMJ connector. So I made a diagram of the connector and repinned it, put it through the firewall and just before I connected it I realized the cabin bay harness had 6 more wires that the doner harness did not. 5 out ot the 6 wires are for cruise control but one wire is for the Air Isolation Valve. So my question is, if my 89 240SX has a wire for the AIV but the replacement harness didn't is it safe to say I don't need the AIV?