craig, do you still have that MAFS for sale? if so, i'm interested..email or IM (email, madmax024@aol.com IM: beakmoney).
also, i have a randomly high idle..its kind of wierd.
sometimes it'll idle perfectly. other times, randomly, it'll idle at 1100, 1500 (it'll flutter between 1300-1600, very very slowly, but usually stays at 1500), 1600 (steady), and 2000. there is no reason for this that i can see. i was thinking bad TPS? i just replaced it a few monthes ago, so i doubt its that. possibly a bad MAFS (which is why i'm interested in craig's), IACV? i just cleaned it (TB cleaner down the hose) a few weeks ago and its been fine until a few days ago. possibly a weak alternator also (lights dim from 5000rpm and up)..what else is there? it doesn't do it all the time, so its not as simple as just lowering the idle.

help me fix my baby!!
also, if need be, IM me, my name is listed above.
thanks!

 

yup, still got it; I'll email you some info in just a minute

looks like all my annoying MAFS for sale replies may have finally paid off

I thought I was in the title of the thread because I was a VE guru too, but you just want me for my parts. I feel so used and so dirty

 

sounds good..yes they did pay off
your name is in the title as i wanted your attention, specially..prove that you're a VE guru and tell me whats wrong with my car!

 

I think its the IACV sticking open. I had the same problem, it would idle very high and I could not find the problem. So I went a head and shot throttle body cleaner into the IACV air inlet and after the third time the idle dropped right down (big sigh of relief).

This is alot cheaper than replacing the MAFS (unless you tested it and determined its bad).

 

is this done with the engine running?

 

I think its the valve within the IACV, that allows additional air during cold start ups. I spoke about it in another current thread. But the other org (very ignorant ones) did'nt believe me. Its actually a wax pellet driven piston (with a return spring) and I think yours is stuck due to carbon deposits.

http://forums.maxima.org/showthread.php?threadid=129629

this next thread I started, and fixed the problem myself (same symptoms as yours)
http://forums.maxima.org/showthread....=IACV+and+help

 

i saw your thread when i cleaned my IACV (maybe not well enough..), but did your racing happen randomly? mine doesn't do it all the time, thats what has me confused..
also, can you clean the IACV with the engine on?

 

I disconnected the hose leading to the IACV (at the point were it leaves the main air intake) its only one spring clamp and then push off the hose. Then spray cleaner into the hose (a real long shot, 5 seconds). then reconect the hose and start the engine. Repeat the pocedure 5 times or until satisfied.

 

how long should i run the engine between shots?

 

I'm having a problem too. My car idles very very high on startup. Like 1500-1700 RPM or so. I understand that it's supposed to idle high on cold starts or whatever, but this does it ALL the time, just about every startup.

It'll literally idle high for about 15 minutes or so and I dont ever have time let it fall down to normal idle. So in return, I pretty much get a neutral drop when I put it into R or D. It bugs me because it just seems like I'm ruining my tranny or something.

Did you leave the engine off, clean it, then start it up, and turn it back off before each repetition of the cleaning?

 

Come on! Ignorant who? I believe you dude..WAX PELLET, I get it. The mysterious IAC is now revealed.

 

just recleaned the IACV..i noticed the first 3 or 4 times i sprayed the carb cleaner in, it ran really rough..after that (i cleaned a total of 6), it died, but after that it was fine..
also, the first few times when it ran rough (i ran it long enough so it would smooth out), there was alot of black smoke coming from the exhaust..i'm assuming this is carbon burning off?

 

Dude, I was referring more towards Dan..hehe

 

I think you should also benefit from doing this cleaning procedure.
Thats correct, the engine is off then spray the cleaner, start the engine let it idle for about a minute, shut it off and repeat the procedure.

 

....ouch!

 

yeah chances are you had quite alot of crap in there. I think this should be done by ALL ve owners on a timley basis, maybe every oil change, or every other oil change. If this problem were left alone it may plug up enough that the IACV would need to be replaced (but I think dissasembly and cleaning would work also).


I just wanted to make sure that while you were doing the service that you temporarily reconnected the hose (just pushing it back on the brass tube), b/c if you did not then the engine would definitley die, b/c the MAFS would not register the air entering the engine.

 

Well just did it...

Let me make sure we're on the same page here:

We're talking about the hose on the firewall side of the intake tube (in between the MAFS and the TB). The hose connects the intake tube on one end, does a 90 degree turn towards the engine block, goes down, and connects to that brass fitting down there kinda under the idle speed adjustment screw. Correct? If we're not on the same page here someone clarify/correct me.

I cleaned out that hose, cleaned down in there around the brass fitting a couple times and didnt notice any difference. Fooey.

After that I adjusted my idle speed. It'd been idling at around 900-1k RPM, so I adjusted it down to around 750.

Then the idle kept hunting on me. As per the FSM I checked for an air intake leak. (I skipped checking the 02 sensor and spark plugs cuz they're new). Well the FSM says to pinch the "blow-by hose" (lowering the blow-by air supply). So I pinch it, and crack. Splits it right down the side. That thing must have been extremely brittle. Crap.

I guess once I get that tube replaced I need to check the EGR Control Valve. Any other suggestions?

 

"Its actually a wax pellet driven piston (with a return spring) and I think yours is stuck due to carbon deposits."

Sounds like the thing works like a coolant thermostat does. I recently replaced all ELEVEN coolant hoses on my SE. Could the hose that supplies coolant to that unit or the passage be plugged with schmutz?

 

Woah....how much did all those hoses cost you?

I probably need to do that. I was snooping around today under there and just about all my hoses have bit the dust. Hard, brittle, and cracking. Crap.

 

Thats the correct hose.
So you sprayed down the hose, reconected it, started the engine, then repeated the procedure? is that correct.

You did not need to disconect the whole hose, just where it met the air stack. Then spray down the hose.


A few weeks ago I replaced ALL the vacuum lines ~$15, mine were ok, but it was time that they should get done. I still have to do the coolant hoses this summer.

 

I got the hoses from Nissan for about $130+... can't find the receipt. Car Quest had most of the shapes, then recommended cut to fit for some others. Their hose didn't look as good as Nissan's (not bad, just not as good) and their shapes weren't perfect. I wanted original...

Couple of the hoses were PITAs to change too.

 

did u ever fix this james? i have been searching and fiddling and i just cant come up with any answers, and im starting to come to the conclusion that i will probably have to replace something (crap)
random news to note:
car basically has problems only in park
problems: detonates a little (not nearly as bad as a dead cylinder), idles at 1500 rpm...both of these problems disappear when cra is put in drive or reverse
solutions: adjusted timing, idle speed, and tps...no result
also sprayed the iacv, this did nothing, but for a while the car would idle at 1500, then rpms would raise to 1700, then it seemed all cylinders missed and rpms would go back to 1500, keep in mind this only happened when i sprayed carb(tb) cleaner in the iacv and started the car...this also went away over time

im guessing my iacv is bad b/c when i went for a test drive once i forgot to plug in the iacv and the car ran the same, which in another old thread i read that unplugging the iacv should result in a drop in rpms....hmmmm

prolly dont matter, but car also shakes noticably from 55-85mph and runs crystal going 0-50 or 95+

bothering every1 with this crap is fun

 

Not sure about your idle issues, but the vibration at a certain speed range sounds like an out of balance wheel/tire. Get them all balanced and see what that does.

 

but if my tires were out of balance wouldnt the car shake at great speeds(100+) also? thanx

 

I am not real clear on which air line you are putting the cleaner into. Is it the big one on the right of the T.B. that is about an inch around, or is it the smaller one before that one that is about a 1/4 around? There are about six hose coming of the trottle body and I have tried three of them, but I still seem to have the idle problem as stated above. I have used two cans of the carb cleaner with not much luck. I have replaced several of the smaller hoses as they seem to have been old and cracked at the ends. I have also tried adjusting the trottle position sensor. With no luck. Any help would be greatly appreciated.
92SE
Thanks

Lance

 

Not necessarily. There's this thing called resonance frequency. Everything in the world has it, from the atomic level up. For the mechanical system consisting of your wheel/tire with it's given imbalance, the resonance frequency (rate of rotation) occurs in the speed range you are feeling it, above or below that it's still out of balance, but far enough from the resonant frequency so it is an imperceptable vibration. Most of the time an imbalaced wheel will cause vibration right in the range of speeds you are describing. Do you feel it in the steering? Or is more throughout the whole car, not so much in the steering wheel. A quick test is to rotated front to back. If it smooths out in the steering, you know the culprit is now on the back of the car. Out of balance wheels on the back are usually much less noticable. Also keep in mind, tires can get out of round too. They may make a sound sort of like bad wheel bearings accompanied by vibration. Putting weights on the rim helps but never gets it 100%. I've seen this, only on cheaper brand tires though. Have 'em all balanced..ususally like 10 bucks each at places like Poop Boys.

 

The Idle is the cold start thing and until the motor warms up to norm operating temps it will rev at around 1.5k-1.7k then drop down to norm operating rpm for idle once warmed up, and if you have an automatic it will rev higher in park or neautral this is a typical thing with most cars, but will drop to norm idle provided the car is at normal operating temperature, and warmed up!

Jared

 

well, after the car sat overnight it seemed better, but i think the idle is only better cause i adjusted the screw all the way in...so now it idles at about 1300 at startup which is what it was doin a long time ago i think...what is good is that the car no longer detonates at idle (hopefully that will stick)...over the next few months ima do sum major matienence stuff and ill keep postin how it goes...so far i just replaced da plugs cause ive read some bad stuff about the bosch stuff (specially 4 4th gens) and i wanted 2 try copper...morrow i do the fuel filter and check air...gon try 2 find time 2 do the knock sensor and get a timing gun and head 2 the track...i jus wanna go 2 da track dammit!

 

I still think its your IACV. Get a new gasket for it (their hard to find, but cheap), and take out your IACV and go to town cleaning it. When you have it removed, do a really good job with some 'mineral spirits' and a stiff paint brush in the area of the spring. Also clean the piston assembley for the electric solenoid.

 

was kinda thinkin the same...but do u know how much of a pain its gonna b 2 get that bish out? i shoulda invested in sum little hands b/f gettin this car...but ill try that...2 nissan i go...

 

Check your temperature sensor, mounted just behind the front cylinder bank. There are two, a small black one that sends information to the gauge in the cabin, and a larger red one that communicates info to the ECU (this is the one that would be the culprit). My friend has a '92 SE, his had an idle problem similar to yours, it would sometimes idle high (roughly 1500k) even after hours of highway driving. The dealership diagnosed a loose cylinder head temperature sensor, tightened the connection, and the idle problem was corrected. Normally a disconnected sensor will trip the Check engine light, but not always.