AIV Repair/Removal, sticky?

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

i wouldn't even mess with the idle, it sounds like you have it right where you want it, if you mess with it now you could possibly screw it up and not be able to get it back to that sweet spot.

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

Well, it's getting lower on cold starts and settling higher after warm up. It likes 500 for a cold start, a 700-750 for a little while and 800-900 after significant warm up. Any suggestions?

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

sounds like a vacuum leak some where around the aac valve or iaa unityou might want to check that before trying to adjust the idle speed.

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

I removed my aiv and there was noticable improvement. Thanks p00t for putting this guide up.

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

Footbagger - Enjoy

Bishoplant im with GZ, sounds like the IACV valve isnt kicking in. When the engine is cold its supposed to open up, provided more air in. For most 240's ive seen 60-90 degree weather cold starts make the idle around 1300rpm and it gradually goes down as the engine warms up. 60 degree and below ive seen usually 1600+rpm when first starting up.

Yorb that rattling is your timing chain. Have someone thats good with cars help you (or slightly mechanically inclined), take off the timing cover (top most cover, and with the car off). its not a complicated process at all, just remove spark plug wires and the vent hose, then unbolt it and off it comes. what your looking for is a loose chain guard sitting or flaping against the top chain. If its there your a lucky man and that should fix the noise.

If there is no top cover OR the top cover is not touching chain then there is a problem furthur down. Most likely the tensioner(s) have deteriorated (keeps the chain tight, prevents it from having slack and flapping around hitting things). Which means you and that mechanically inclined friend of yours will have to get a timing chain kit and replace the chain and tensioners.

If your car has high miles, and the marbles sound is present all the time at idle then you will have to perform the check. If it makes the marbles sound randomly on cold starts for a few seconds it is normal (chain picking up slack).

PHEW.:pimp

Oh, ALSO::::When you bolt the Timing Cover back on torque the bolts only to 5-7 ft/lbs!!!!! they snap very easy, be very gentle!!!

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

Thanks for the suggestions, but please clarify. Is it AAC, IAA or IACV? I'll test them this weekend and respond with results.

Ant

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

the IAA is all the idle control systems together as one unit. IACV-AAC is what is responsable for adding extra air when the engine is cold. (bolted to it)

Im at home now looking at the FSM, it looks like the AAC gets its air feed from the IAA itself... so if it idles theres no way that it could be cut off... im at a loss.

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

thanks for the info p00t, but curiously enough my problem completely went away after a day or 2. i wiggled the plugs a bit, but other than that nothing really. occasionally at a stop light my rpm will drop to 500 or so, but then it goes back to the 700-800 range. seems pretty normal. and no more rattling. =) thanks though, i am keeping all this information in mind.

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

Just a quick question...what will happen if you don't plug up the vaccum hoses? Mine's been off for like 4 months and no problems, except bad idle (clagged IACV I think). I got a hose cap for the metal exhaust tube with a clamp, works good.

I also 'removed' the EGR - cut the metal pipe going between the EGR and the exhaust manifold. Then I capped both end, along with clamps.

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

Here's another pic of the AIV:

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

p00t wrote:the IAA is all the idle control systems together as one unit. IACV-AAC is what is responsable for adding extra air when the engine is cold. (bolted to it)

poot,

Please clarify. Where is this part, what does it look like and what is it bolted to?

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

MAN! this was a complete life saver! i removed the AIV in 10 mins and the thing ran like gold again! OMG im so happy. thank you

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

Here's what it should look like after the AIV is removed:

The metal tube in the center of the pic, coming off of the manifold, is the one you cap. BE SURE to clamp it good...I prolly blew off 4 caps before I bought some good $2 clamps :pface

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

bishopant wrote:poot,

Please clarify. Where is this part, what does it look like and what is it bolted to?

its bolted directly to the IAA, basically if you look at where the idle adjust screw is, then follow down under the intake manifold there should be a small unit with 2-3 plugs going into it, thats the IAA. the AAC is bolted to it, i cant really tell you what its position is on the IAA right now... next time im home ill scan the fsm pic of it. For right now you should just check all the wires going to the IAA and see fi there are any bad connections (actually pull the plug out and check for corrosion and bad grounding).

maybe some threads to help you:

http://www.nissaninfiniticlub....e+low

http://www.nissaninfiniticlub....e+low

only useful post is the last one:http://www.nissaninfiniticlub....e+low

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

i did this to my 89 and it runs alot better, and took me about 10mins total. IF i get cold air intake, will i need any any of those questions.

Post by **stutt944** » Sun Jun 22, 2003 9:05 am

did this to my '93 today, and i am very impressed. the engine is noticeably smoother all the way thru the rev range. nice write up, p00t.

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

:pimp okay, okay, okay (Joe Pesci ) I have a 92 240sx w/ 160k, bought it new. Last year did the clutch, brakes, timing chains (real PIA). Now it has the bad idle karma thing, but mine starts up cold just fine, idles perfect.....intil it warms up and then it trys to idle ~ 400 rpm. also it it acts like it hits a rev limiter around 3500, no power. AIV ?

Post by **89onevia** » Sun Jun 22, 2003 9:05 am

I did this today to my 89 coupe and it peroformes a whole lot better, to block the metal tube I used a Honda wheel stud and just clamped it.

Post by **POS_S13** » Sun Jun 22, 2003 9:05 am

coupla days ago i cleaned out my aiv on my 89, idle is perfect now! i had to struggle a bit with 2 of the 4 bolts and ended up stripping em but it was all werth it in the end. i have noticed a little bit quicker throttle response but i wasn't expecting nothing but a smoothe idle.

Post by **Dman1100** » Sun Jun 22, 2003 9:05 am

i did this today and it has seemed to fix my idle very well. To block the pipe, i used the short rubber hose that was on the AIV and stuffed it with six nickels.i put a clamp on one end and put it over the pipe and clamped it down. I think it will hold up pretty good

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

pOOt....

This sounds like the problem my '90 has had on three seperate occasions. It would all of a sudden seem to lose power, start to idle like crap/die, not rev above 3500rpm....then it would be fine a half hour later with nothing done to it. It's been serviced (typical air/oil/plugs etc) and happened once after that...My research in the Chiltons had already lead me to the AIV, that and the fact that my AIV resonator has a small hole in it with a spring(?) poking out. Like I said it has only done it three times over a year, and cleared up on it's own. Sound like the same problem to you?

'90 240 on hiatus....Daddy's playin in da Big Sand.

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

the aiv will just bog the idle a bit, it should not effect how high you can rev.

are you saying the resonator box has a hole in it (it should just be hollow)? that wouldnt effect the car performance wise too much because the aiv connects to the intake before the MAS. so no unmetered air would be getting by. the big problem with that however is that you are letting air in that hasnt gone through the filter.... bugs, dirt, water, can now get into your engine quite easily and gum up the works.

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

Hmmm.....well, I don't know then, since it has only done this once every few months and then disappeared I won't be able to pin point it w/o using a scanner for codes I guess. Probably still remove the PAIRC just for the helluvit. Thanks.

Post by **sc0rp** » Sun Jun 22, 2003 9:05 am

This will be a long story so I hope you are ready. I'm fairly new to my 240 which is a 91 240sx se coupe. Most of the cars I've had and worked on in the past were pre-emission control bs. My car idles horribly, it's running very rich and sputters at all rpms under 3k. Gas mileage is like 7 miles per gallon and it has no power. I fouled out my new plugs in a month. I tried all the typical stuff (plugs, wires, distributur button, even coil) After none of that fixed it, I took it to a diagnostic place thinking if it was a sensor they could plug it up and tell me. They told me it was leaky fuel injectors and it would cost 800 to fix. Compression and fuel pressure is ok. So I paid 70 for the diag and ordered some injectors myself for 300. Needless to say, that didn't fix the problem so I started lookin on the web for answers. I just cleaned my AIV and no change. Tomorrow I 'll try removing it and see what happens. What else could it be and where should I start? I've already put to much money into this for it not to fix anything. HELP!!!!!!!!!!!!!!!!!

Post by **stutt944** » Sun Jun 22, 2003 9:05 am

CHECK THE MAF. CHECK THE MAF. CHECK THE MAF.

almost all power problems can be traced straight to the mass-air-flow sensor. so CHECK THE MAF. clean it. replace it if its terribly bent or broken in some way.

ps - sorry to hear you were had by the "needs new injectors" theory nissan techs like to lay on 240 customers. better luck next time.

Post by **sc0rp** » Sun Jun 22, 2003 9:05 am

I got an ECU code of 12 as well. Where is the MAF and what's the easiest way to clean/check? ya, I know I'm a n00b at it.

Post by **Touchdown038** » Sun Jun 22, 2003 9:05 am

MAF is right in between your air filter box and the black intake tube horizontal to the engine, bolted to the metal throat.

Post by **sc0rp** » Sun Jun 22, 2003 9:05 am

gotcha, figured that one out

thanx though. I'm assuming the code of 12 on the ECU refers to this as well. The car has started to not idle at all and run even more poorly.

Post by **stutt944** » Sun Jun 22, 2003 9:05 am

get a nissan FSM for your car. get one. tells all...codes included.

Post by **sc0rp** » Sun Jun 22, 2003 9:05 am

I replaced the MAF, car runs alot smoother but idle is way to high. tried adjusting the idle screw, but it doesn' change it enough. Car idles between 900-1100 rpms when hot. read up to see what all else I've done with this car. removed AIV, replaced MAF, replaced fuel injectors, 02 sensor, plugs, wires, ditributor button. still need some advice, just drop in an sr20det and be done with it?

AIV Repair/Removal, sticky?

HELP!!!!!!!!!

k, now what?

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