Setting The Idle...?

[BreedOfSpawn]

A few weeks ago I noticed my Idle being really shotty it should shut off while I was driving and coming to a stop. I cleaned the EGR and AAC which fixed the problem for about 2 weeks then today I started noticing my rpms are getting droppy again... I figure if I reclean it and set the Idle to 50+ it may buy me some more time before I have to keep recleaning it.

Any Suggestions?

BTW Im running a 93 240SX Stock.

[elgarvo616]

try cleaning the IACV

[BreedOfSpawn]

Will give it a shot and see what it turns up

[DjPantsSpecR]

start looking for vac leaks

often the vac lines themselves will rupture and cause a vacuum leak.

If i had to name the one i believe it is its the 90 degree bend line (i think actually two 90 degree bends in diff directions) that runs from the EGR to the valve that actuates the EGR right by it. tis the one that looks like a diaphragm and has to vac lines running to it on the top.

I've had that line fracture three times on two different cars. On my auto with an IACV it causes it to run fine almost always. Usually after you get to a stop and wait a while, the rpms start to drop, then they jump and drop and so on. Its not quite an EGR, FPR, or an IACV problem, its really a combo.

on my white car i plugged the large line leaving the air intake tube. This leads to a metal tube that goes right to the IACV. You have to start the car witht he throttle a little open, and then save it from dying right away, but then it idles like champ. I eventually removed the entire system, but i ran with it only plugged for about a year.

when the EGR vac line failed on this car i never noticed until a heard a serious hissing one day. no idle probs with no IACV

[vancouverbc]

djpants, sounds like you plugged the air regulator and iacv. The aac is the main valve of the iaa unit. Clean mayb every ten years.

[DjPantsSpecR]

this man is correct.

But to be fair i've ditched the PAIR, AAC, EGR and IACV, as well as the charcoal canister, and anything that uses vacuum other than the FPR and the Brake booster.

however, many long term stupid problems including this idle surging were caused by that simple EGR line problem

[BreedOfSpawn]

I dunno its really weird why this happens but always happens during the night I can drive the car fine during the day the idle sits quiet but the second I flip those lights up at night and turn them on and drive it starts acting really weird... Kinda jumpy at times and back and forth alot with the rpm's. They tend to drop to the 500's very quickly and then settle themselves back up... Sometimes it'll drop below 500 for a second or 2 and the engine sounds like its dying slowly about to shut off by sputtering then it kicks back up again and sets the rpm's back to 650... Its odd anyhow tomorrow morning im gonna take it in for an oil change and have them take a quick look at it again should be alright.

[vancouverbc]

Breedofspawn

1. These problems are pretty esoteric. If you have to go to mechanic, go to a mechanic who specializes in nissans. Otherwise, you will waste a lot of money.

2. The attached pic shows the large brass scew that you have to unscrew to get access to AAC piston and spring. It is covered in epoxy that has to be removed to unscrew screw. You should be able to unscrew this screw and take out the spring and piston without taking the iaa unit off. If the epoxy is still on the screw, it has not been cleaned properly. You may need a mirror to get clear look. If the epoxy has been removed, this screw can move from vibration so you may have to reset it. I used some goop to seal it to prevent it moving from vibration.

3.If your car is not stalling when you come to a stop sign and only gives you problems when you turn your lights on, that sounds very specific. Someone might have had this experience. I'm not certain , but it may be the FICD valve that is supposed to increase idle to compensate for lights.

4. I would definitely disconnect the hose going from the PAIR valve to the air filter housing. PAIR valve (most people call it AIV) is next to useless and causes a lot of problems. Mechanic cant disconnect because it is pollution control. You dont have to remove the PAIR valve. THis should help with your idle. You may have to adjust idle after you disconnect this hose, though.

[BreedOfSpawn]

See heres my biggest problem and its very frustrating because I cant help but feel angry at myself for this is the fact that when it comes to car mechanics I am a total N00b...

I know nothing of the AIV the IACV or the MAF... Since I've had this car I've had to learn without no one really teaching me how other then the things I read... The pictures you post up are amazing and teach me alot but dont help because I dont even kno how or where to start looking to find that part.

P.S I have also searched the forums alotta threads come up but none with what im looking at that explains where to find these components also... Ive searched the online manual for the car and searched the words AIV, AAC, AICV and PAIR and nothing came up... So I am now completly frusterated at spending alotta money for a car I've always wanted that doesnt work...

[vancouverbc]

The AIV valve is the easiest thing to do. It is very accessible. You just disconnect the hose at the air filter. Its just an air hose. Not pressurized.The IACV is hard to find. A mirror and flashlight helps. You should make a point of finding the idle adjustment screw. You pretty much have to make this a hobby/passion to get anywhere.

[vancouverbc]

AIV

[DjPantsSpecR]

vancover, these are some good pictures. you should just add a little something somewhere and get it into a faq. I wish i could take pictures, but yours are, imo, very useful along with the other pictures

[BreedOfSpawn]

Thanx alot guys now I'm getting somewhere WOOOOOOOHOOOO sorry about before and being frusterated you know how it is sometimes. Im gonna pull that aiv hose off today and see if it makes a big difference.

[BreedOfSpawn]

Ripped off the AIV today and blocked it off as stated wasnt hard to do once I figured it all out thank you all btw. The car has already started to feel alot better while driving which is nice. RPMS still rev down every now and then hasnt stalled yet since the throttlebody cleaning 2 weeks ago.

Gonna start figuring out the IACV and get that spiffied soon dont want this thing causing me problems at work. Any advice on how to locate the IACVa little easier would be nice if anyone knows a simple way of oproaching the problem.

[vancouverbc]

No, it's not easy. You have to just stare at until you start to recognize parts of it that are visible. Study the pics.

[BreedOfSpawn]

I believe I found it... But its definetly not easy to get access too... Can I take the screw off without having to take the FICD valve right off? Like leave the IACV intact underneath the throttlebody?

[BreedOfSpawn]

Well car is running alot better still need to clean the AICV. I noticed something really funny today. It was raining here all day and at night my gf needed to pull her car out of the driveway and I was parked behind her so I had to pull my 240 out so she could take off. After I reversed out of the driveway I put my car into 1st and drove up the driveway as I was driving up I stepped on the clutch and touched the break a little my rpms dropped from 1300 to 0 instantly for a second or 2 while in the 0 position the check engine and oil lets blinked on, the car then reved it self back up to 650rpm and the lights shut off... Weird? any thoughts?

[BreedOfSpawn]

Bump!? any suggestions on how to access the AICV? Seems like I'd have to do some removing?

[DjPantsSpecR]

I'm not the IACV spokesman, as first i plugged it, and second i removed/blocked it off

but im ot sure how you can get it off to clean it without first removing the upper intake manifold. Have you ever done that before?

[Kittychubbs]

well the problem with my friends 240 is that when she steps on it it takes a long time (crawls) to 25 -30 mph but after that its normal.what could be wrong with it??its Automatic 91

[BreedOfSpawn]

Nope I've never removed the upper intake manifold on a car before. But I am sure I'll figure it out. I have all the diagrams in my Chiltons Manual. But thanx for the advice I thought maybe there was a way to remove it without having to but its all good.